Epidemiological Insights into Feline Leukemia Virus Infections in an Urban Cat (Felis catus) Population from Brazil.

Feline leukemia virus (FeLV) is a retrovirus distributed worldwide in domestic cats and with different outcomes (progressive, regressive, abortive, focal). The present study reports an epidemiological survey of FeLV frequency and the evaluation of some risk factors and the two main disease outcomes (progressive and regressive) in an urban cat population from Brazil. A total of 366 cats with sociodemographic information and p27 FeLV antigen test performed were included in the study. FeLV DNA (provirus) in the blood samples of all cats was detected via real-time polymerase chain reaction (qPCR). Plasma samples from 109 FeLV-positive and FeLV-negative cats were also submitted to reverse transcription (RT-qPCR) to determine the FeLV viral load. The results demonstrated that 112 (30.6%) cats were positive through the p27 antigen and/or qPCR. A risk factor analysis demonstrated that cats without vaccination against FeLV (OR 9.9, p < 0.001), clinically ill (OR 2.9, p < 0.001), with outdoors access (OR 2.7, p < 0.001), and exhibiting apathetic behavior (OR 3.1, p < 0.001) were more likely to be infected with FeLV. FeLV-infected cats were also more likely to present with anemia (OR 13, p < 0.001) and lymphoma (OR 13.7, p = 0.001). A comparative analysis of the different detection methods in a subset of 109 animals confirmed FeLV infection in 58 cats, including 38 (65.5%) with progressive, 16 (27.6%) with regressive, and 4 (6.9%) with probably focal outcome diseases. In conclusion, this study demonstrates a high prevalence of FeLV in this urban cat population from Brazil and highlights the need to establish more effective prevention strategies (such as viral testing, vaccination programs, specific care for FeLV-positive cats) to reduce diseases associated with this virus in Brazil.

Epidemiological and clinicopathological findings of feline immunodeficiency virus and feline leukemia virus infections in domestic cats from the Brazilian semiarid region.

Feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) are retroviruses of great importance for domestic cats with a worldwide distribution. A retrospective study was conducted to determine the epidemiological and clinicopathological aspects of the infection by FIV and FeLV in cats from the Brazilian semiarid region. Cats treated between 2011 and 2021 at the teaching veterinary hospital of the Federal Rural University of the Semi-Arid Region that were submitted to a point-of-care (POC) test to detect anti-FIV IgG antibodies and FeLV antigen were enrolled in the study. Overall, 454 cats were selected, of which 30.2% [95% CI = 26.0% - 34.3%] were FIV-positive, 1.1% [95% CI = 0.9% - 1.2%] were FeLV-positive, and 0.7% [95% CI = 0.1% - 1.3%] were coinfected by both retroviruses. No statistical association was found between the studied retroviruses (P = 0.144). Multivariable analysis detected significant associations between FIV infection and male sex [OR = 5.7, 95% CI = 3.0-10.7, P < 0.0001), age between 19 and 78 months [OR = 5.2, 95% CI = 2.2-12.1, P < 0.0001], age greater than 78 months [OR = 12.8, 95% CI = 5.1-31.9, P < 0.0001], crossbreed [OR = 4.1, 95% CI = 1.2-13.4, P = 0.021], the presence of oral disease [OR = 2.1, 95% CI = 1.3-3.4, P = 0.004], reduced red blood cell (RBC) count [OR = 3.7, 95% CI = 1.9-7.2, P < 0.0001], and an albumin:globulin (A:G) ratio lower than 0.6 [OR = 3.4, 95% CI = 1.6-7.1, P = 0.001]. No statistical analyses were performed for FeLV infection due to the low number of positive animals. In the quantitative analyses of hematological parameters, FIV-positive cats presented lower values for RBC, hemoglobin, hematocrit, lymphocytes, and platelets compared to the negative animals. In the biochemical profile, cats infected with FIV showed higher creatinine, urea, total protein, and globulin values, while lower values for albumin and A:G ratio were observed (P < 0.05). The findings of this study characterized the prevalence, clinicopathological findings, and risk factors associated with FIV and FeLV in cats from the Brazilian semiarid region. They may help support veterinary practitioners in diagnosing feline retroviruses. The FIV prevalence observed is among the highest reported in Brazil, demonstrating the need for prevention and control strategies for this retrovirus.

Feline immunodeficiency virus, feline leukemia virus and Leishmania spp. prevalence in cats from shelters in Mato Grosso do Sul, Brazil / Vírus da imunodeficiência felina, vírus da leucemia felina e Leishmania spp. em gatos de abrigos de Mato Grosso do Sul, Brasil

Abstract Diseases such as those caused by feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) represent health problems for cats. Feline leishmaniasis (FL) has been reported in several cities across the country. The objective was to carry out a clinical-epidemiological and laboratory study of FIV, FeLV and FL in cats from shelters in Dourados, Mato Grosso do Sul, Brazil. Blood samples and swabs from the conjunctival and nasal mucosa were obtained from 75 cats, from four animal shelters. Serology for FIV and FeLV was performed. For Leishmania, polymerase chain reaction (PCR) was performed on blood, conjunctiva and nasal mucosa. In the immunochromatographic serological test, seven cats tested positive for FIV and none for FeLV. No samples was positive in PCR for Leishmania. The study showed that despite the presence of human and canine leishmaniasis in the studied region, Leishmania spp. were absent in the cats studied. To avoid an increase in contagion in shelters, it is essential isolate cats with FIV.

Resumo Doenças como as causadas pelos vírus da imunodeficiência felina (FIV) e vírus da leucemia felina (FeLV) representam problemas de saúde para os gatos. A leishmaniose felina (LF) tem sido relatada em diversas cidades do país. O objetivo deste trabalho foi realizar um estudo clínico-epidemiológico e laboratorial de FIV, FeLV e LF em gatos de abrigos em Dourados, Mato Grosso do Sul, Brasil. Amostras de sangue e swabs da mucosa conjuntival e da mucosa nasal foram obtidas de 75 gatos, dos quatro abrigos de animais. Foi feita a sorologia para FIV e FeLV. Para Leishmania foi realizada a reação em cadeia da polimerase (PCR) em sangue, conjuntiva e mucosa nasal. No teste sorológico imunocromatografico, sete gatos apresentaram resultado positivo para FIV e nenhum para FeLV. Nenhuma amostra foi positiva na PCR para Leishmania. O estudo demonstrou que apesar da presença de leishmaniose humana e canina, na região estudada, não foi encontrado Leishmania spp. nos gatos analisados. Para evitar o aumento do contágio em abrigos é fundamental isolar os gatos com FIV.

Anti-Leishmania spp. antibody detection in domestic cats from a visceral leishmaniasis transmission area.

Feline leishmanial infection is reported worldwide, but the epidemiological role of domestic cats in the leishmaniasis cycle remains unclear, and cats might act as cryptic reservoir hosts in endemic areas with no feline leishmaniosis cases. Considering that, a serological screening for anti-Leishmania spp. antibodies was performed by indirect immunofluorescence antibody test (IFAT) in 389 necropsied cats' serum samples from a new visceral leishmaniasis transmission area with no feline leishmanial infection reported to unveil if the cats are being exposed to the parasite. The overall seroprevalence for Leishmania spp. was 11.05% (43/389). No association was found between sex, neutering status, age group, breed, coat length, feline immunodeficiency virus (FIV) infection, and Leishmania spp. antibody detection. A positive association was found with coat color (cats within the orange spectrum with white [particolor]) (OR = 2.47, CI 95% 1 - 6.13, P = 0.044) and a negative association (OR = 0.38, CI 95% 0.18 - 0.79, P = 0.01) between feline leukemia virus (FeLV) infection and IFAT positivity for Leishmania spp. Therefore, it is concluded that the seroprevalence found was greater than 10%, indicating contact of the protozoan with cats in the region served.

Molecular characterization of Brazilian FeLV strains in São Luis, Maranhão Brazil.

The feline leukemia virus (FeLV) belongs to the Retroviridae family and Gammaretrovirus genus, and causes a variety of neoplastic and non-neoplastic diseases in domestic cats (Felis catus), such as thymic and multicentric lymphomas, myelodysplastic syndromes, acute myeloid leukemia, aplastic anemia, and immunodeficiency. The aim of the present study was to carry out the molecular characterization of FeLV-positive samples and determine the circulating viral subtype in the city of São Luís, Maranhão, Brazil, as well as identify its phylogenetic relationship and genetic diversity. The FIV Ac/FeLV Ag Test Kit (Alere™) and the commercial immunoenzymatic assay kit (Alere™) were used to detect the positive samples, which were subsequently confirmed by ELISA (ELISA - SNAP® Combo FeLV/FIV). To confirm the presence of proviral DNA, a polymerase chain reaction (PCR) was performed to amplify the target fragments of 450, 235, and 166 bp of the FeLV gag gene. For the detection of FeLV subtypes, nested PCR was performed for FeLV-A, B, and C, with amplification of 2350-, 1072-, 866-, and 1755-bp fragments for the FeLV env gene. The results obtained by nested PCR showed that the four positive samples amplified the A and B subtypes. The C subtype was not amplified. There was an AB combination but no ABC combination. Phylogenetic analysis revealed similarities (78% bootstrap) between the subtype circulating in Brazil and FeLV-AB and with the subtypes of Eastern Asia (Japan) and Southeast Asia (Malaysia), demonstrating that this subtype possesses high genetic variability and a differentiated genotype.

Phylogenetic identification of feline leukemia virus A and B in cats with progressive infection developing into lymphoma and leukemia.

To date, only a few studies have examined the impacts of feline leukemia virus (FeLV) subgroups on disease development in spontaneously infected cats. The present study identified FeLV-A and FeLV-B subgroups in cats with lymphoma and leukemia and explored the phylogenetic relationships of env sequences. Twenty-six cats with lymphoma (n=16) or leukemia (n=10) were selected. FeLV p27 antigen positivity was determined using ELISA, and proviral DNA in blood samples was detected using nested PCR. Positive animals in both tests were classified as cases of FeLV progressive infection and subjected to a second nested PCR for env amplification and subgroup determination. Six samples of FeLV-A and five samples of FeLV-B were sequenced using the Sanger method, and the results were used to build a phylogenetic tree and estimate evolutionary divergence. Among cats with lymphoma, 68.8% carried FeLV-AB and 31.2% FeLV-A. Among cats with leukemia, 70% carried FeLV-AB and 30% FeLV-A. Regarding cat characteristics, 50% were young, 30.8% young adults, and 19.2% adults; 88.5% were mixed-breed and 11.5% pure breed; and 42.3% were males and 57.7% were females. Among lymphomas, 62.5% were mediastinal, 31.3% multicentric, and 6.3% extranodal. Regarding histological classification, lymphoblastic and small non-cleaved-cell lymphomas were the most frequently detected. Among leukemia cases, 30% were acute lymphoid, 30% chronic myeloid, and 40% acute myeloid. Phylogenetic analysis showed that FeLV-A SC sequences were closely related to the Arena, Glasgow-1, and FeLV-FAIDS variants. Meanwhile, FeLV-B SC sequences were divergent from one another but similar to the endogenous FELV env gene (enFeLV). In conclusion, FeLV-AB is prevalent in cats with lymphoma and leukemia, highlighting the genetic diversity involved in the pathogenesis of these neoplasms in Brazil.

Coinfection with Leishmania infantum and Toxoplasma gondii in Domestic Cats from a Region with a High Prevalence of Feline Immunodeficiency Virus.

The aim of this study was to investigate the coinfection of feline retroviruses (feline immunodeficiency virus-FIV, and the feline leukemia virus-FeLV) with Leishmania infantum and Toxoplasma gondii and the factors associated with these pathogens in domestic cats from Mossoró, a city endemic for canine and human leishmaniasis situated in the semiarid region of Northeast Brazil. Blood samples from 120 cats were collected, and an epidemiological questionnaire was applied to investigate the risk factors associated with the infections. Retroviruses, L. infantum, and T. gondii infections were assessed using a point-of-care ELISA and quantitative PCR (qPCR), indirect fluorescent antibody test (IFAT) and qPCR, and IFAT, respectively. The overall seroprevalences observed were 35% (95% CI = 27.0-43.8%) for FIV, 0.8% (95% CI = 0.1-4.5%) for FeLV, 25.8% (95% CI = 18.8-34.3%) for T. gondii, and 4.2% (95% CI = 1.7-9.3%) for L. infantum. Coinfection with FIV and L. infantum was observed in 2.5% (3/120) of the assessed cats, while 12.5% (15/120) were coinfected with FIV and T. gondii. No significant association was found among the investigated agents (p > 0.05). The factors associated with FIV infection in the multivariable analysis were male sex and age above 78 months. The findings of this study demonstrated a high rate of FIV infection in cats from the Brazilian semiarid region and the exposure of these animals to zoonotic and opportunistic agents. Due to the immunosuppressive potential of FIV, cats infected with this retrovirus should be screened for coinfections with L. infantum and T. gondii, and preventative measures should be adopted.

Could Phylogenetic Analysis Be Used for Feline Leukemia Virus (FeLV) Classification?

The surface envelope (SU) protein determines the cell tropism and consequently the pathogenesis of the feline leukemia virus (FeLV) in felids. Recombination of exogenous FeLV (exFeLV) with endogenous retroviruses (enFeLV) allows the emergence of more pathogenic variants. Currently, phenotypic testing through interference assays is the only method to distinguish among subgroups-namely, FeLV-A, -B, -C, -E, and -T. This study proposes a new method for FeLV classification based on molecular analysis of the SU gene. A total of 404 publicly available SU sequences were used to reconstruct a maximum likelihood tree. However, only 63 of these sequences had available information about phenotypic tests or subgroup assignments. Two major clusters were observed: (a) clade FeLV-A, which includes FeLV-A, FeLV-C, FeLV-E, and FeLV-T sequences, and (b) clade enFeLV, which includes FeLV-B and enFeLV strains. We found that FeLV-B, FeLV-C, FeLV-E, and FeLV-T SU sequences share similarities to FeLV-A viruses and most likely arose independently through mutation or recombination from this strain. FeLV-B and FeLV-C arose from recombination between FeLV-A and enFeLV viruses, whereas FeLV-T is a monophyletic subgroup that has probably originated from FeLV-A through combined events of deletions and insertions. Unfortunately, this study could not identify polymorphisms that are specifically linked to the FeLV-E subgroup. We propose that phylogenetic and recombination analysis together can explain the current phenotypic classification of FeLV viruses.

Acute erythroid leukemia in a cat infected with feline leukemia virus

Background: Erythroid leukemia is a myeloproliferative hematopoietic disorder considered acute when there is a predominance of blasts in the bone marrow. It is frequently reported in cats infected with feline leukemia virus, but it is unclear whether this virus is involved in the oncogenesis. The clinical signs in cats are anorexia, apathy, weight loss, with evolution from 2 weeks to 2 months, pale mucous membranes, hemorrhages, ascites, salivation, and dyspnea due to pleural effusion. This affection responds little to chemotherapy with an unfavorable prognosis. The aim of this study is to report a case of a feline leukemia virus infected cat with the onset of severe hemolytic anemia. Case: A 8-year-old male mixed breed cat was attended with a history of anorexia, oligodipsia, apathy, progressive weight loss, and yellowish color of urine for 7 days. Laboratorial exams showed anemia (with metarubricytes, acanthocytes and ghost cells), leukocytosis and FeLV reagent test. The cat underwent treatment with methylprednisolone acetate and supportive care. One day later, the animal returned with icteric mucous membranes, and emesis. A blood count was performed that found worsening anemia, increased leukocytosis, and lymphocytosis. Abdominal ultrasound showed cholangiohepatitis and lymphadenomegaly in mesenteric lymph nodes. Treatment was started with ondansetron, metronidazole, and amoxicilin with potassium clavulanate. The cat returned after 3 days and laboratorial exams revealed worsening of blood parameters, so blood transfusion was performed. After 2 days, the patient started with dyspnea and hypothermia, that evolved to cardiorespiratory arrest. The body was sent to necropsy and histopathology, where blast cells and rubricytes were found in blood vessels of various organs. The bone marrow was markedly cellular with complete disappearance of adipose tissue. Most of the cells were blasts with abundant and eosinophilic cytoplasm, central nucleus with finely dotted chromatin and a large nucleolus. There were rubricytes, which made possible to confirm acute erythroid leukemia as a morphological diagnosis. Discussion: The clinical signs observed in acute erythroid leukemia are lethargy, inappetence, fever, splenomegaly, mild lymphadenomegaly, associated with leukocytosis, severe anemia, and thrombocytopenia. The reported animal presented signs similar to those described in the literature except that there was no change in platelet counts. The diagnosis of leukemia was reached after histopathology, and it is made when is observed more than 30% of myeloblasts and monoblasts together or when the blast cells count including rubriblasts is greater than 30%. Although chemotherapy, the prognosis is usually poor. It is essential to perform the myelogram for the diagnosis of myeloid leukemias in vivo. In this report, we only achieve final diagnosis after the cat's death, due to the aggressive behavior of the disease. Clinicians must be aware of the likely development of acute erythroid leukemia whenever a feline leukemia virus infected cat presents hemolytic anemia to get an early diagnosis, since this is an extremely aggressive disease, to propose prompt chemotherapy and give the patient a longer survival period.

Classification of lymphoma in cats and its relationship with the detection of feline leukemia vírus proviral DNA / Classificação do linfoma em gatos e sua relação com a detecção do DNA pró-viral do vírus da leucemia felina

In this retrospective and prospective study, histopathological and immunohistochemical analyses of 62 cases of lymphomas in cats were performed to classify the anatomic forms and subtypes, according to the WHO guidelines, and correlate it to FeLV proviral DNA detected using PCR. The most common anatomical form was gastrointestinal (40.3%, 25/62), followed by multicentric (29%, 18/62), mediastinal (17.7%, 11/62) and extranodal (12,9%, 8/62). Among the lymphoma subtypes, diffuse large B-cell lymphoma (DLBCL) (30.6%, 19/62) was the most commonly diagnosed followed by peripheral T-cell lymphoma (PTCL) (29%, 18/62) and enteropathy associated T-cell lymphoma type 2 (14.5%, 9/62). DNA extraction from paraffin-embedded neoplastic tissue was obtained in 28 cases and FeLV proviral DNA was detected by PCR, in 23 of these. Of the cases presenting with FeLV proviral DNA, nine (32%) were of the multicentric form, five (22%) of the mediastinal and extranodal forms and four (17%) of the gastrointestinal form. The most frequent subtypes with FeLV proviral DNA, independent of the anatomical form, were DLBCL (39.1%, 9/23) and PTCL (34.7%, 8/23). The presence of the FeLV proviral DNA in 23 cats of this study, probably had association with the multicentric form of lymphoma and higher occurrence in the DLBCL and PTCL subtypes.

Neste estudo retrospectivo e prospectivo, análises histopatológicas e imuno-histoquímicas de 62 casos de linfomas em gatos foram realizadas para classificar as formas anatômicas o e subtipos do linfoma, de acordo com as diretrizes da OMS. Além disso, foi realizada a extração de DNA dos tumores incluídos na parafina para obtenção de DNA pró-viral do FeLV por PCR, e relacionada com os exames anteriores. A forma anatômica mais comum foi a gastrointestinal (40.3%, 25/62), seguida pela multicêntrica (29%, 18/62), mediastinal (17,7%, 11/62) e extranodal (12,9%, 8/62). Entre os subtipos de linfoma, o linfoma difuso de grandes células B (DLBCL) (30.6%, 19/62) foi o mais comumente diagnosticado, seguido por linfoma de células T periférico (PTCL) (29%, 18/62) e o linfoma de células T associado a enteropatia tipo 2 (14.5%, 9/62). A extração de DNA de tecido neoplásico emblocado em parafina foi obtida em 28 casos e o DNA pró-viral de FeLV foi detectado por PCR, em 23 deles. Dos casos com DNA pró-viral do FeLV, nove (32%) eram da forma multicêntrica, cinco (22%) das formas mediastinal e extranodal e quatro (17%) da forma gastrointestinal. Os subtipos mais frequentes com DNA pró-viral do FeLV, independente da forma anatômica, foram DLBCL (39.1%, 9/23) e PTCL (34.7%, 8/23). A presença do DNA pró-viral do FeLV em 23 gatos deste estudo, provavelmente teve associação com a forma multicêntrica do linfoma e maior ocorrência nos subtipos DLBCL e PTCL.

High rate of feline immunodeficiency virus infection in cats in the Brazilian semiarid region: Occurrence, associated factors and coinfection with Toxoplasma gondii and feline leukemia virus.

To evaluate the occurrence of feline immunodeficiency virus (FIV) and factors associated with this and to demonstrate occurrences of coinfection with Toxoplasma gondii and feline leukemia virus (FeLV) in cats, a total of 103 blood samples were collected from owned cats, during home visits. To diagnose FIV and FeLV, immunochromatographic kit was used and serological diagnoses of T. gondii, the indirect immunofluorescence test was performed. The occurrence of FIV-seropositive cats was 23.3% (24/103) and the factor associated with infection was male sex. T. gondii seropositivity of 53.4% (55/103) was observed and 75% of FIV cases (18/24) were positive for T. gondii coinfection. Only 0.9% (1/103) was positive for FeLV. It can be concluded that the seroprevalence of FIV in cats in the Brazilian semiarid region is high and that FIV positive cats were also likely to be T. gondii seropositive, while FeLV had very low occurrence in the study region.

Pathological and immunohistochemical aspects of acute megakaryoblastic leukaemia in a cat - Short communication.

An adult, mixed-breed, feline leukaemia virus (FeLV-) positive female cat was presented with mucosal jaundice and a history of anorexia and constipation for three days. Physical examination revealed splenomegaly, cachexia, and dehydration. Humane euthanasia was conducted, followed by postmortem examination. Grossly, the cat was icteric, and presented hepatomegaly with multifocal white spots and splenomegaly. Histologically, the bone marrow was nearly completely replaced by a proliferation of megakaryocytes and megakaryoblasts, and there was a proliferation of fibrous connective tissue. Similar neoplastic proliferation was observed infiltrating the liver, lymph nodes, spleen, kidney, skeletal muscle, and lungs. Immunohistochemistry was performed for von Willebrand Factor (VWF), CD79α, CD3, feline immunodeficiency virus, FeLV, and CD61. Marked cytoplasmic labelling was observed in the neoplastic cells for FeLV, VWF and CD61, corroborating the diagnosis of acute megakaryoblastic leukaemia.

Infection with Dirofilaria immitis and Other Infections in Cats and Dogs from Rio de Janeiro, Brazil: The Need for Prophylactic Enforcement.

PURPOSE: Dirofilaria immitis, a mosquito-borne nematode that primarily infects dogs, can equally infect cats. Although there have been numerous studies on canine heartworm prevalence in Brazil, there have been few studies on feline infections. Feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) are both life-threatening retroviruses transmitted directly between cats. Infections with Ehrlichia spp. and Anaplasma spp. are highly prevalent among dogs in Brazil, with Rhipicephalus sanguineus being the main vector for both bacteria. This study aimed to gather information on these infections among dogs and cats in the metropolitan area of Rio de Janeiro by performing rapid point-of-care tests for prophylactic enforcement. METHODS: Surplus samples of serum or plasma from private laboratories were tested by enzyme-linked immunosorbent assay (ELISA) (SNAP Feline Triple Test or SNAP 4Dx Plus Test). RESULTS: The prevalence of heartworm disease was 7% among dogs and 0.9% among cats, the latter being 12.9% of the former. The prevalence of FIV and FeLV was 4.3 and 11.9%, respectively. Among dogs, the seroprevalence of Ehrlichia spp. and Anaplasma spp. was 27.1 and 9.8%, respectively, and Borrelia burgdorferi was not detected. CONCLUSION: Given that such infections circulate among pets, prophylactic measures should be encouraged by small animal practitioners.

Molecular Detection of Feline Leukemia Virus in Oral, Conjunctival, and Rectal Mucosae Provides Results Comparable to Detection in Blood.

Feline leukemia virus (FeLV) infection causes immunosuppression, degeneration of the hematopoietic system, and fatal neoplasms. FeLV transmission occurs mainly by close social contact of infected and susceptible cats. Developing procedures for the diagnosis of feline retroviruses is crucial to reduce negative impacts on cat health and increase the number of animals tested. Blood collection requires physical or chemical restraint and is usually a stressful procedure for cats. Our objective was to evaluate the use of samples obtained from oral, conjunctival, and rectal mucosae for the molecular diagnosis of FeLV. Whole blood and oral, conjunctival, and rectal swabs were collected from a total of 145 cats. All samples were subjected to the amplification of a fragment of the gag gene of proviral DNA. Compared to blood samples used in this study as a reference, the accuracies for each PCR were 91.72, 91.23, and 85.50% for samples obtained by oral, conjunctival, and rectal swabs, respectively. The diagnostic sensitivity and specificity were 86.11 and 97.26% for the oral swabs, 90 and 92.59% for the conjunctival swabs, and 74.24 and 95.77% for the rectal swabs, respectively. The kappa values for oral, conjunctival, and rectal swabs were 0.834, 0.824, and 0.705, respectively. The diagnosis of these samples showed the presence of proviral DNA of FeLV in oral and conjunctival mucosae. In conclusion, mucosal samples for the molecular diagnosis of FeLV are an excellent alternative to venipuncture and can be safely used. It is faster, less laborious, less expensive, and well received by the animal.

Epidemiological, pathological and immunohistochemical aspects of 125 cases of feline lymphoma in Southern Brazil.

A retrospective study compiling cases of feline lymphoma diagnosed during 12 years (2004-2016) in Southern Brazil was performed. A total of 125 cases of lymphoma diagnosed in cats were reviewed, and information including age, breed, sex and tumour topography were collected. FeLV and FIV immunohistochemical tests were performed, as well as immunophenotyping of lymphomas. The alimentary form represented the most common presentation (42/125), followed by mediastinal lymphoma (35/125). Out of 125 cases, 79 presented positive retroviral immunostaining in tumour tissue (52 FeLV alone, 14 FIV alone and 13 presented FIV and FeLV co-infections), 66/125 of the cases were of T-cell origin and 59/125 of the cases were of B-cell origin. The median age of cats with T-cell lymphoma was 120 months (10-240 months), and 60 months (6-204 months) for cats with B-cell lymphoma. The most frequent alimentary tumour presentation was the enteropathy-associated T-cell lymphoma (type 1), and the major type of mediastinal tumour observed was diffuse large B-cell lymphoma. Considering only mediastinal and alimentary lymphomas (n = 77), the prevalence of mediastinal lymphoma in FeLV-positive cats was 2.21 times higher than the prevalence of this type of tumour in FeLV-negative cats (P = .036). Mediastinal lymphoma was more frequently observed in younger cats, and the prevalence of mediastinal tumours in these animals was 3.06 times higher than the prevalence of this tumour form in old cats (P = .0125). The present study indicates that retroviral infections still play an important role in the development of feline lymphomas in southern Brazil.

B220 expression as an immunological marker for differentiation of Feline Leukemia Virus carrying cats / A expressão de B220 como um marcador imunológico para diferenciação de gatos portadores do vírus da Leucemia Felina

ABSTRACT: Feline leukemia virus (FeLV) causes an infection in cats that, in some cases, can also be reported with other pathologies, such as infection with feline immunodeficiency virus (FIV), feline infectious peritonitis (FIP), and lymphoma. Although, a compromised immune response is reported in these animals, little is known about the immunological state of their cells. To shed some light in this area, we studied peripheral blood samples from both infected and non-infected cats with FeLV, with or without FIV, FIP, and lymphoma. We tested a panel of monoclonal antibodies (n=11) against mouse and human antigens and we reported that cat leukocytes can be stained with anti-mouse B220 monoclonal antibody; therefore, percentages of B cells were evaluated in different cat groups. Our results showed that cats with FeLV and FIP, or with leukemia, presented a large decrease in B220+ mononuclear cells. However, FeLV+ cats without clinical signs, or with unspecific clinical signs, had the same amount of B220+ mononuclear cells as healthy cats (control cats). Since the expression of B220 is exclusively restricted to the naïve B cell population, we inferred that the absence of these B cells in FeLV+ cats is related to other conditions that affect B cell numbers, such as viral infections and leukemias. Therefore, the amount of naïve B cells in peripheral blood (i.e., B220+ cells) can be used to identify FeLV+ cats concomitantly carrying FIP or leukemia, from FeLV+ cats with lymphoma or without any clinical signs.

RESUMO: O vírus da leucemia felina (FeLV) causa de uma infecção em gatos, que também podem ter outras patologias, como a imunodeficiência felina (FIV), a peritonite infecciosa felina (FIP) e linfoma. Embora uma resposta imune comprometida seja encontrada nestes animais, pouco se sabe sobre o estado imunológico de suas células. Para ampliar o número de testes com a finalidade de avaliar o estado imunológico destes animais, estudamos amostras de sangue periférico de gatos infectados, ou não, com FeLV, e que apresentavam (concomitantemente) FIV, FIP e linfoma. Para isto, amostras de sangue foram marcadas com um painel de anticorpos monoclonais contra antígenos de camundongos e humanos (n = 11), para avaliar seu potencial para estudos imunológicos em gatos. De todo o painel de anticorpos testados, apenas o anticorpo anti-B220 de camundongo foi capaz de marcar leucócitos de gato. Nossos resultados mostraram que os gatos com FeLV e FIP, ou com leucemia, apresentaram uma grande diminuição nas células mononucleares B220+. No entanto, gatos FeLV+ sem sinais clínicos, ou com sinais clínicos inespecíficos, tiveram a mesma quantidade de células B220+ que os gatos saudáveis (gatos controle). Como a expressão de B220 é restrita à população de células B naïve, podemos inferir que a ausência dessas células B em gatos FeLV+ está relacionada a outras condições que afetam o número destas células, como infecções virais e leucemias. Portanto, a quantidade de células B naïve no sangue periférico pode ser usada para identificar gatos FeLV+ concomitantemente portadores de PIF ou leucemia, de gatos FeLV+ com linfoma ou sem sinais clínicos.

Unusual feline Dirofilaria immitis infection: a case report / Infecção incomum por Dirofilaria immitis em felino: relato de caso

Abstract Cats are less susceptible to Dirofilaria immitis infection than dogs. Although rare, the feline disease can be fatal even with low parasitic loads. The infection is often asymptomatic or has non-specific symptoms that are mainly associated with the death of immature worms. Microfilaremia is rare and transient. Normally, microfilaremia, when present, lasts for not more than 33 days. This study describes a feline case presenting with non-specific clinical signs and prolonged microfilaremia. Case: a random bred cat infected by feline leukemia virus (FeLV) that was found to be microfilaremic by chance. The infection was detected by the presence of microfilariae in a blood smear and was confirmed by antigen test (SNAP Feline Triple Test, Idexx®) and echocardiogram.

Resumo Gatos são menos susceptíveis à infecção por Dirofilaria immitis do que cães. Apesar de rara, a doença nos gatos pode ser fatal mesmo com baixas cargas parasitárias. Muitas vezes, a doença é assintomática ou apresenta sintomas inespecíficos, principalmente associados com a morte de formas parasitárias imaturas. Microfilaremia é rara e transitória. Normalmente, quando ocorre microfilaremia, ela permanece por, no máximo, 33 dias. Este estudo descreve o caso de um felino que apresentava sinais inespecíficos e microfilaremia prolongada: um gato sem raça definida, portador de infecção pelo vírus da leucemia felina (FeLV) que foi diagnosticado como microfilaremico ao acaso. A infecção foi detectada pela presença de microfilárias em esfregaço sanguíneo e, posteriormente, confirmada pelo teste de antígenos (SNAP Feline Triple Test, Idexx®) e por ecocardiograma.

Unusual feline Dirofilaria immitis infection: a case report / Infecção incomum por Dirofilaria immitis em felino: relato de caso

Cats are less susceptible to Dirofilaria immitis infection than dogs. Although rare, the feline disease can be fatal even with low parasitic loads. The infection is often asymptomatic or has non-specific symptoms that are mainly associated with the death of immature worms. Microfilaremia is rare and transient. Normally, microfilaremia, when present, lasts for not more than 33 days. This study describes a feline case presenting with non-specific clinical signs and prolonged microfilaremia. Case: a random bred cat infected by feline leukemia virus (FeLV) that was found to be microfilaremic by chance. The infection was detected by the presence of microfilariae in a blood smear and was confirmed by antigen test (SNAP Feline Triple Test, Idexx®) and echocardiogram.(AU)

Gatos são menos susceptíveis à infecção por Dirofilaria immitis do que cães. Apesar de rara, a doença nos gatos pode ser fatal mesmo com baixas cargas parasitárias. Muitas vezes, a doença é assintomática ou apresenta sintomas inespecíficos, principalmente associados com a morte de formas parasitárias imaturas. Microfilaremia é rara e transitória. Normalmente, quando ocorre microfilaremia, ela permanece por, no máximo, 33 dias. Este estudo descreve o caso de um felino que apresentava sinais inespecíficos e microfilaremia prolongada: um gato sem raça definida, portador de infecção pelo vírus da leucemia felina (FeLV) que foi diagnosticado como microfilaremico ao acaso. A infecção foi detectada pela presença de microfilárias em esfregaço sanguíneo e, posteriormente, confirmada pelo teste de antígenos (SNAP Feline Triple Test, Idexx®) e por ecocardiograma.(AU)

B220 expression as an immunological marker for differentiation of feline leukemia virus carrying cats / A expressão de B220 como um marcador imunológico para diferenciação de gatos portadores do vírus da leucemia felina

Feline leukemia virus (FeLV) causes an infection in cats that, in some cases, can also be reported with other pathologies, such as infection with feline immunodeficiency virus (FIV), feline infectious peritonitis (FIP), and lymphoma. Although, a compromised immune response is reported in these animals, little is known about the immunological state of their cells. To shed some light in this area, we studied peripheral blood samples from both infected and non-infected cats with FeLV, with or without FIV, FIP, and lymphoma. We tested a panel of monoclonal antibodies (n=11) against mouse and human antigens and we reported that cat leukocytes can be stained with anti-mouse B220 monoclonal antibody; therefore, percentages of B cells were evaluated in different cat groups. Our results showed that cats with FeLV and FIP, or with leukemia, presented a large decrease in B220+ mononuclear cells. However, FeLV+ cats without clinical signs, or with unspecific clinical signs, had the same amount of B220+ mononuclear cells as healthy cats (control cats). Since the expression of B220 is exclusively restricted to the naïve B cell population, we inferred that the absence of these B cells in FeLV+ cats is related to other conditions that affect B cell numbers, such as viral infections and leukemias. Therefore, the amount of naïve B cells in peripheral blood (i.e., B220+ cells) can be used to identify FeLV+ cats concomitantly carrying FIP or leukemia, from FeLV+ cats with lymphoma or without any clinical signs.(AU)

O vírus da leucemia felina (FeLV) causa de uma infecção em gatos, que também podem ter outras patologias, como a imunodeficiência felina (FIV), a peritonite infecciosa felina (FIP) e linfoma. Embora uma resposta imune comprometida seja encontrada nestes animais, pouco se sabe sobre o estado imunológico de suas células. Para ampliar o número de testes com a finalidade de avaliar o estado imunológico destes animais, estudamos amostras de sangue periférico de gatos infectados, ou não, com FeLV, e que apresentavam (concomitantemente) FIV, FIP e linfoma. Para isto, amostras de sangue foram marcadas com um painel de anticorpos monoclonais contra antígenos de camundongos e humanos (n = 11), para avaliar seu potencial para estudos imunológicos em gatos. De todo o painel de anticorpos testados, apenas o anticorpo anti-B220 de camundongo foi capaz de marcar leucócitos de gato. Nossos resultados mostraram que os gatos com FeLV e FIP, ou com leucemia, apresentaram uma grande diminuição nas células mononucleares B220+. No entanto, gatos FeLV+ sem sinais clínicos, ou com sinais clínicos inespecíficos, tiveram a mesma quantidade de células B220+ que os gatos saudáveis (gatos controle). Como a expressão de B220 é restrita à população de células B naïve, podemos inferir que a ausência dessas células B em gatos FeLV+ está relacionada a outras condições que afetam o número destas células, como infecções virais e leucemias. Portanto, a quantidade de células B naïve no sangue periférico pode ser usada para identificar gatos FeLV+ concomitantemente portadores de PIF ou leucemia, de gatos FeLV+ com linfoma ou sem sinais clínicos.(AU)

Feline lymphoma in the nervous system: pathological, immunohistochemical, and etiological aspects in 16 cats / Linfoma no sistema nervoso de felinos: aspectos patológicos, imuno-histoquímicos e etiológicos em 16 gatos

The pathological, immunohistochemical (IHC), and etiological features of lymphoma involving the nervous system (NS) in cats were analyzed through a retrospective study (2004-2017) in Rio Grande do Sul State, Brazil. The NS involvement was observed in 16 (12.2%) of 125 felines with lymphoma. Young cats were mainly affected, with a median of 24 months old. Most cases were secondary central NS lymphoma, whereas in three cats, the NS involvement was primary. IHC revealed 14 (87.5%) FeLV-positive, six FIV-positive, and one FeLV/FIV-negative cats. Distribution of feline lymphoma in the NS was 8/16 in the spinal cord, 7/16 in the brain, and 1/16 in the paravertebral nerves and ganglia (neurolymphomatosis). The lymphoma pattern in the spinal cord was exclusively extradural, often focal (6/8), and located in the lumbar (3/6), sacral (1/6), thoracic (1/6), and cervical segments (1/6). Brain neuroanatomical patterns were: leptomeningeal lymphomatosis (4/7), lymphomatous choroiditis (2/7), and intradural lymphoma (1/7). The feline with primary neurolymphomatosis presented a marked thickening of paravertebral nerves and ganglia from the sacral region. B-cell lymphoma (75%) was often diagnosed, and diffuse large B-cell lymphoma (DLBCL) (11/16) was the main subtype. T-cell lymphoma (25%) was less commonly observed and was classified as peripheral T-cell lymphoma (PTCL) (3/16) and T-cell lymphoblastic lymphoma (T-LBL) (1/16).(AU)

Os aspectos patológicos, imuno-histoquímicos (IHQ) e etiológicos do linfoma envolvendo o sistema nervoso de felinos foram analisados através de um estudo retrospectivo (período de 2004-2017) no Estado do Rio Grande do Sul, Brasil. O envolvimento do sistema nervoso foi observado em 16 (12,2%) dos 125 felinos com linfoma desse estudo e afetou principalmente, jovens com idade mediana de 24 meses. A grande maioria dos casos o linfoma era secundário no sistema nervoso central e somente em três gatos o linfoma foi primário do sistema nervoso. Na IHQ, 14 (87,5%) casos foram positivos para FeLV, seis (37,5%) para FIV, e um foi negativo para ambos. A distribuição do linfoma no sistema nervoso foi em 8/16 felinos na medula espinhal, 7/16 no encéfalo e em 1/16 em nervos e gânglios paravertebrais (neurolinfomatose). Na medula espinhal, o padrão do linfoma foi exclusivamente extradural e frequentemente focal (6/8), localizadas nos segmentos lombares (3/6), sacrais (1/6), torácicos (1/6) e cervicais (1/6). No encéfalo, os padrões neuroanatômicos observados foram: linfomatose leptomeningeal (4/7), coroidite linfomatosa (2/7), linfoma intradural (1/7). No felino diagnosticado com neurolinfomatose primária, foi observado acentuado espessamento dos nervos e gânglios paravertebrais da região sacral. Os linfomas de células de células B (75%) foram os mais frequentes e o principal tipo foi o linfoma difuso de grandes células B (11/16). Os linfomas de células T (25%), menos observados, foram classificados como linfomas de células T periférico inespecífico (3/16) e linfoma linfoblástico T (1/16).(AU)