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.

Low transmission rates of Equine infectious anemia virus (EIAV) in foals born to seropositive feral mares inhabiting the Amazon delta region despite climatic conditions supporting high insect vector populations.

BACKGROUND: Marajó Island, within in the Amazon River Delta, supports numerous bands of feral equids including the genetically distinct Marajoara horses. Approximately 40% of the equids on the island are infected with Equine infectious anemia virus (EIAV). This high seropositivity rate coupled with the need to preserve rare breeds such as the Marajoara horse precludes euthanasia as the primary means for controlling EIAV in this region. In the absence of iatrogenic transmission, spread of this lentivirus is mediated primarily by hematophagous insects, whose year-round prevalence on the island is supported by favorable climatic conditions. In addition, cases of vertical EIAV transmission have been observed suggesting inclusion of seropositive mares in restorative breeding programs could result in their progeny becoming infected with this virus either pre-parturition or post-partum via hematophagous insects. Therefore, the aim of this study was to evaluate EIAV vertical and post-partum insect-mediated transmission rates among foals born to seropositive feral mares until natural weaning. Serum samples from foals born to seropositive feral mares within the Soure municipality, of Marajó Island, were collected to investigate their serological status, using an indirect ELISApgp45, with positive samples confirmed using the classical agar gel immunodiffusion (AGID) assay. RESULTS: The serological status of 28 foals were monitored over a 2-year period with some subjects, depending on their date of birth, being sampled up to six times. All foals remained with their respective mares until fully weaned at approximately 10 months of age. Only 2 foals (7.14%) in the study group became seropositive against EIAV. CONCLUSION: The results demonstrate that in most cases it is possible to obtain seronegative foals born to and eventually weaned by EIA positive mares, even in equatorial regions where substantial rainfall and high temperatures favor the proliferation of insect vectors.

qPCR assay for the detection of pseudocowpox virus.

Pseudocowpox is a zoonosis caused by pseudocowpox virus (PCPV), which mainly affects cows but can be an occupational disease of humans. The aim of the study was to validate a quantitative polymerase chain reaction (qPCR) assay for the detection of PCPV. The assay was able to detect up to 1000 copies of PCPV per µL in field samples, with a sensitivity of 80% and a specificity of 100%. We did not observe any cross-reactivity between PCPV-positive samples and samples that were positive for other genetically similar viruses. The repeatability and reproducibility were adequate according to parameters preestablished in official test validation manuals.

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.

RT-qPCR for the diagnosis of the vesiculovirus Cocal virus.

Cocal virus (COCV) is one of the causative agents of vesicular stomatitis, presenting clinical signs indistinguishable from those caused by foot-and-mouth disease virus (FMDV). Therefore, the differentiation of these two viruses via laboratory diagnosis is essential. The objective of this study was to develop and validate a real-time quantitative PCR (RT-qPCR) protocol for the diagnosis of COCV directly from epithelial samples. The method developed had 97% accuracy at 3950 pfu and a repeatability error of 1.29%. RT-qPCR was able to distinguish COCV from other viruses that cause vesicular diseases, an important factor because seroneutralization may produce cross-reactivity between COCV and vesicular stomatitis Alagoas virus (VSAV). No epithelial sample originating from vesicular disease outbreaks between 2014 and 2018 in Brazil was positive for COCV.

Molecular detection, histopathological analysis, and immunohistochemical characterization of equine infectious anemia virus in naturally infected equids.

Equine infectious anemia (EIA), a disease caused by equine infectious anemia virus (EIAV), is considered an obstacle to the development of the horse industry. There is no treatment or vaccine available for EIA, and its pathogenesis, as well as the immune response against the virus, is not fully understood. Therefore, an immunohistochemistry assay was developed for the detection of viral antigens in tissues of equids naturally infected with EIAV. Sections of organs of six equids from Apodi-RN, Brazil, that tested positive for EIA by serological tests (ELISA and AGID) were fixed in 10% formalin solution and embedded in paraffin. Immunohistochemistry was performed using a polyclonal anti-EIAV antibody. EIAV antigens were observed in red spleen pulp cells and hepatic sinusoids, as well as bronchiolar and alveolar epithelial cells of the lungs and proximal and distal tubules of the kidneys. The presence of EIAV in the spleen and liver was expected due to viral tropism by macrophages, which are abundantly present in these organs. However, EIAV was also found in lung and kidney epithelial cells, indicating that the virus infects cell types other than macrophages. In conclusion, the immunohistochemical assay standardized in this study was able to detect EIAV antigens in spleen, liver, kidney and lung cells from naturally infected EIAV equids. Immunostaining observed in the spleen confirms viral tropism by mononuclear phagocytes; however, the presence of EIAV in lung and kidney epithelial cells indicates that virus may be eliminated in urine and/or oronasal secretions, suggesting new routes for viral excretion.

Bovine herpesvirus 6 in buffaloes (Bubalus bulalis) from the Amazon region, Brazil.

This study presents the first description of Bovine herpesvirus 6 (BoHV-6) that was isolated from buffaloes of Amazon region in Brazil. Phylogenetic analysis showed that the BoHV-6 Brazilian strains clustered with the sequence of BoHV-6 from elsewhere available at the GenBank. It was observed in some buffaloes with lymphoproliferative disease in one herd, thus the animals were also tested for Bovine leukemia virus (BLV), which has been associated to lymphoma in bovines. All animals were negative to BLV. These results indicate that BoHV-6 is present in buffaloes in Brazil, but the importance and impact of this infection and its association with any illness is still undefined.

Feline leishmaniasis in an animal shelter in northeastern Brazil: Clinical aspects, coinfections, molecular detection, and serological study of a new recombinant protein.

Infection and clinical cases of leishmaniasis caused by Leishmania infantum in cats have been increasingly reported in several countries, including Brazil. In this study, we used an enzyme-linked immunosorbent assay (ELISA) and an immunochromatographic test (ICT) based on a recombinant antigen (rKDDR-plus) to detect anti-Leishmania antibodies in cats from an animal shelter in northeastern Brazil. We compared the results with an ELISA using L. infantum crude antigen (ELISA-CA). We also investigated the presence of Leishmania DNA in blood or ocular conjunctival samples as well as the association between Leishmania PCR positivity and serological positivity to feline immunodeficiency virus (FIV), feline leukemia virus (FeLV) and Toxoplasma gondii. Concerning serological assays, a higher positivity was detected using the ICT-rKDDR-plus (7.5%; 7/93) as compared to ELISA-rKDDR-plus (5.4%; 5/93) and ELISA-CA (4.3%; 4/93). Upon PCR testing, 52.7% (49/93) of the ocular conjunctival swabs and 48.3% (44/91) of the blood samples were positive. Together, PCR and serological testing revealed overall positivities of 73.1% (68/93) and 12.9% (12/93), respectively. Among PCR-positive samples, 45.5% (31/68) showed co-infection with FIV, 17.6% (12/68) with FeLV, and 82.3% (56/68) with T. gondii. More than half of the PCR-positive cats showed at least one clinical sign suggestive of leishmaniasis (58.8%; 40/68) and dermatological signs were the most frequent ones (45.5%; 31/68). Both tests employing the recombinant antigen rKDDR-plus (i.e., ICT-rKDDR-plus and ELISA-rKDDR-plus) detected more positive cats than the ELISA-CA but presented low overall accuracy. PCR testing using either blood or ocular conjunctival samples detected much more positive cats than serological tests.

Evidence of SARS-CoV-2 infection and co-infections in stray cats in Brazil.

The zoonotic virus SARS-CoV-2, which causes severe acute respiratory syndrome in humans (COVID-19), has been identified in cats. Notably, most positive cases were in cats that had close contact with infected humans, suggesting a role for humans in animal transmission routes. Previous studies have suggested that animals with immune depletion are more susceptible to SARS-CoV-2 infection. To date, there is limited evidence of SARS-CoV-2 infections in stray and free-range cats affected by other pathogens. In this study, we investigated infections caused by SARS-CoV-2, Leishmania spp., Toxoplasma gondii, Mycoplasma spp., Bartonella spp., Feline leukemia virus (FeLV), and Feline immunodeficiency virus (FIV) in stray cats from an urban park in Brazil during the COVID-19 pandemic. From February to September 2021, 78 mixed-breed cats were tested for SARS-CoV-2 and hemopathogens using molecular analysis at Américo Renné Giannetti Municipal Park, Belo Horizonte, Minas Gerais, Brazil. An enzyme-linked immunosorbent assay (ELISA) was used to detect IgG in T. gondii. None of the animals in this study showed any clinical signs of infections. The SARS-CoV-2 virus RNA was detected in 7.7 % of cats, and a whole virus genome sequence analysis revealed the SARS-CoV-2 Delta lineage (B.1.617.2). Phylogenetic analysis showed that SARS-CoV-2 isolated from cats was grouped into the sublineage AY.99.2, which matches the epidemiological scenario of COVID-19 in the urban area of our study. Leishmania infantum was detected and sequenced in 9 % of cats. The seroprevalence of T. gondii was 23.1 %. Hemotropic Mycoplasma spp. was detected in 7.7 % of the cats, with Mycoplasma haemofelis and Candidatus Mycoplasma haemominutum being the most common. Bartonella henselae and Bartonella clarridgeiae were detected in 38.5 % of the cats, FeLV was detected in 17,9 %, and none of the cats studied tested positive for FIV. This study reports, for the first time, the SARS-CoV-2 infection with whole-genome sequencing in stray cats in southeastern Brazil and co-infection with other pathogens, including Bartonella spp. and Feline leukemia virus. Our study observed no correlation between SARS-CoV-2 and the other detected pathogens. Our results emphasize the importance of monitoring SARS-CoV-2 in stray cats to characterize their epidemiological role in SARS-CoV-2 infection and reinforce the importance of zoonotic disease surveillance.

Quantification of in vitro replication kinetics of Alagoas vesiculovirus isolates by digital droplet RT-PCR.

Vesicular stomatitis caused by Alagoas vesiculovirus (VSAV) has generated disease outbreaks in Brazil, mainly in the northeast region. Phylogenetic studies divide the isolates into three distinct genotypes (A, B, and C). However, there is no description of how this genetic divergence reflects on the phenotype of VSAV isolates such as in vitro replication fitness. Therefore, the objective of this work was to evaluate the ability of three distinct genotypes of Brazilian isolates of VSAV to grow in different cell-culture lines (BHK-21, Vero, and NCI-H1299). Quantification of viral RNA was performed using RT-PCR digital droplet from supernatant of cell culture collected every 4 h for a period of 24 h of viral growth in three different cell lines (BHK-21, Vero, and NCI-H1299). It was observed that the genotype C isolate has the lowest replication efficiency among the three analyzed viruses, without major changes in the copies of viral RNA over the entire time of the study.

Development and validation of a method for purification of mallein for the diagnosis of glanders in equines.

BACKGROUND: The allergic test of mallein is one of the most frequently used tests, together with the Complement Fixation Test (CFT), for the diagnosis of glanders in endemic areas. Mallein, a purified protein derivative (PPD), is produced similarly to PPD tuberculin and the end product is a primarily proteic antigen, which is only poorly purified. The immuno-allergic activity of mallein is believed to be due to a high molecular weight group of proteins present in the antigen. To improve the quality of the antigen, in terms of sensitivity and specificity, a new method of mallein production was developed, in which purification was accomplished by ultrafiltration in a Tangential Flow Filtration system (TFF). RESULTS: The TFF methodology efficiently separated the high and low molecular weight protein groups of mallein. The five TFF-purified malleins, produced from Burkholderia mallei strains isolated from clinical cases of glanders in Brazil, proved to be more potent than standard mallein in the induction of an allergic reaction in sensitized animals. Regarding specificity, two of the purified malleins were equivalent to the standard and three were less specific. CONCLUSION: Some of the TFF-purified malleins showed considerable potential to be used as an auxiliary test in the diagnosis of glanders.

Evaluation of three different genomic regions for detection of bovine leukemia virus by real-time PCR.

Bovine leukemia virus (BLV) is an oncogenic member of the genus Deltaretrovirus. BLV infects cattle worldwide and is responsible for significant economic losses. The objective of this study was to validate real-time quantitative PCR (qPCR) for the detection of BLV. After identification of the most efficient qPCR, the limits of detection, repeatability, and reproducibility were determined. The results indicate that qPCR can be easily reproduced between laboratories with high sensitivity. The test variation was low in samples from lesions suggestive of bovine leukosis or whole blood.

Evaluation of post-mortem diagnostic tests' sensitivity and specificity for bovine tuberculosis using Bayesian latent class analysis.

This study aimed to evaluate the performance of real-time PCR (qPCR), ELISA IDEXX™, and bacterial isolation as post-mortem diagnostic tests in animals with lesions compatible with bovine tuberculosis detected by Brazilian Federal Inspection Service as part of the bovine tuberculosis active surveillance. Bayesian latent class models were used to estimate diagnostic tests' sensitivity, specificity, correlations, predictive values and frequency of infected animals. Samples of tuberculosis-suggestive lesions collected by FIS sanitary inspection routine in slaughterhouses from 11 Brazilian states were analyzed. Isolation was the most sensitive technique, 94.54% (95% Credible Interval (CrI) 90.09%-97.65%), qPCR was 64.69% (95% CrI 54.41%-74.15%) sensitive and ELISA IDEXX™ 26.74% (95% CrI 22.82%-30.97%). Tests' specificities were 98.19% (95% CrI 95.75%-99.45%), 93.49% (95% CrI 79.28%-99.66%), 95.53% (95% CrI 91.71%-98.02%) respectively. Despite its low sensitivity, ELISA IDEXX™ was able to identify positive samples that were not detected by the other techniques. These samples had high probability to be true positives given ELISA's positive predictive value. The correlations between qPCR and isolation were neither biologically nor statistically significant. The low sensitivity of the qPCR is a limiting factor to its use as a post-mortem diagnosis in bovine tuberculosis suggestive lesions. Its use could be recommended in situations of high prevalence, or in parallel association with other tests, such as ELISA IDEXX™. ELISA IDDEX™ should not be used as a unique test, or in substitution of the other tests, for the post-mortem diagnosis of bovine tuberculosis due to its sensitivity.

First description of Theiler's disease-associated virus infection and epidemiological investigation of equine pegivirus and equine hepacivirus coinfection in Brazil.

Recent advances in the study of equine pegivirus (EPgV), Theiler's disease-associated virus (TDAV) and equine hepacivirus (EqHV) highlight their importance to veterinary and human health. To gain some insight into virus distribution, possible risk factors, presence of liver damage and genetic variability of these viruses in Brazil, we performed a cross-sectional study of EPgV and TDAV infections using a simultaneous detection assay, and assessed EqHV coinfection in different horse cohorts. Of the 500 serum samples screened, TDAV, EPgV and EPgV-EqHV were present in 1.6%, 14.2% and 18.3%, respectively. EPgV-positive horses were present in four Brazilian states: Espírito Santo, Mato Grosso do Sul, Minas Gerais and Rio de Janeiro. Serum biochemical alterations were present in 40.4% of EPgV-infected horses, two of them presenting current liver injury. Chance of infection was 2.7 times higher in horses ≤5 years old (p = 0.0008) and 4.9 times higher in horses raised under intensive production systems (p = 0.0009). EPgV-EqHV coinfection was 75% less likely in horses older than 5 years comparatively to those with ≤5 years old (p = 0.047). TDAV-positive animals were detected in different horse categories without biochemical alteration. Nucleotide sequences were highly conserved among isolates from this study and previous field and commercial product isolates (≥88% identity). Tree topology revealed the formation of two clades (pp = 1) for both EPgV and TDAV NS3 partial sequences. In conclusion, the widespread presence of EPgV-RNA suggests an enzootic infection with subclinical viremia in Brazil. Horse management can influence virus spread. This first report of TDAV-infected horses outside the USA reveals the existence of subclinical viremic horses in distant geographical regions. EPgV and TDAV have similar circulating isolates worldwide. These findings contribute to global efforts to understand the epidemiology and pathogenesis of these equine viruses.

Genotyping of the pseudorabies virus by multiplex PCR followed by restriction enzyme analysis.

Suid herpesvirus 1 (SuHV-1) is the causative agent of Aujeszky's disease. The infectious agent has only one serotype, but it was classified by restriction enzyme analysis of the whole genome into four genotypes, named I to IV. The aim of this study was to standardize a rapid method for genotyping SuHV-1 without virus isolation, using a multiplex-PCR followed by enzymatic restriction analysis. The complete genome of the virus was analyzed in silico to determine the restriction sites for the enzyme BamHI. Primers were designed to flank sites with emphasis on certain points of differentiation of genotypes. The standard PCRs were able to detect the SuHV-1 and also to differentiate genotypes from brain tissue of infected pigs. The BamHI-PCR is a rapid, practical, and sensitive way to genotype SuHV-1.

Molecular characterization of the env gene from Brazilian field isolates of Bovine leukemia virus.

Molecular characterization of Bovine leukemia virus (BLV) isolates from Brazil using the env gene sequences revealed a high conservation of this gene. In most cases the substitutions corresponded to silent transitions. In addition, cystein residues, potential glycosylation sites, neutralization domains and other critical residues involved with the envelope structural domains and viral infectivity were conserved. Most of the substitutions found in the aminoacid sequences of the gp51 protein were localized in the G and H epitopes. Using the SIFT software, it was predicted that they should not alter the protein functions. Phylogenetic analyses showed that partial or complete env gene sequences grouped in three or four phylogenetic clusters, respectively. The sequences from the Brazilian isolates had similar mutation rates as compared to samples from other countries, and belonged to at least two phylogenetic clusters.