Plasma procalcitonin kinetics in healthy dogs and dogs undergoing tibial plateau leveling osteotomy.

BACKGROUND: Procalcitonin (PCT) is a well-established biomarker for bacterial infection in human patients. OBJECTIVES: We aimed to analyze the kinetics of plasma PCT (pPCT) in healthy dogs and dogs with canine cranial cruciate ligament (CCL) rupture undergoing tibial plateau leveling osteotomy (TPLO). METHODS: This prospective, longitudinal study included 15 healthy dogs and 25 dogs undergoing TPLO. Hematology, pPCT, and C-reactive protein (CRP) were assessed on 3 consecutive days in healthy dogs and 1 day preoperatively and days 1, 2, 10, and 56 postoperatively. Inter- and intraindividual variability of pPCT were assessed in healthy dogs. Median pPCT concentrations of dogs with CCL rupture preoperatively were compared with healthy controls, and median pPCT concentrations, as well as percentage change post anesthesia, arthroscopy, and TPLO, were compared with baseline. For the correlation analysis, the Spearman rank correlation test was used. RESULTS: Inter- and intraindividual variabilities of pPCT in healthy dogs were 36% and 15%, respectively. Median baseline pPCT concentrations were not significantly different between healthy dogs (118.9 pg/mL; IQR: 75.3-157.3 pg/mL) and dogs undergoing TPLO (95.9 pg/mL; IQR: 63.8-117.0 pg/mL). Plasma PCT concentrations were significantly lower immediately post- than preoperatively (P < 0.001). CRP, WBC, and neutrophil concentrations increased significantly on post-OP day 2 and had normalized by day 10. CONCLUSIONS: These results indicate that CCL rupture, as well as anesthesia, arthroscopy, and TPLO combined, are not associated with increased pPCT concentrations in dogs with uncomplicated recovery. Considering the high intraindividual variability, individual serial measurements rather than a population-based reference interval should be considered.

Antibody kinetics and exposure to Toxoplasma gondii in cats: a seroepidemiological study.

Domestic cats are the most important definitive hosts for Toxoplasma gondii, the agent of an important global zoonosis. Serial sera from cats orally inoculated either withT. gondii tissue cysts (n = 3) or sporulated oocysts (n = 3) and from 65 client-owned cats, plus sera from 1,757 client-owned cats presented to veterinarians in Switzerland were analysed for an antibody response to T. gondii by ELISA. Risk factors for seropositivity and prevalence were estimated with a generalised linear and beta regression model. The first model examined the association of an OD405 value as the dependent variable, with gender, age, and outside access as possible independent variables. In the second model, we first analysed the data assuming a bimodal distribution representing two overlapping distributions of OD405 values from positive and negative cats, enabling the assignment of a probability of true infection status to each cat. Mean probabilities of true infection status across groups represent an estimate of true prevalence. These probabilities were then regressed against age, gender and outside access. Antibody kinetics in cats orally inoculated with tissue cysts, shedding oocysts, did not differ significantly from those of cats inoculated with sporulated oocysts without detectable oocyst excretion, suggesting extraintestinal parasite invasion and exposure to tachyzoites in both situations at an early stage of infection. Analysis of serial serum samples suggested a persisting long-term humoral immune response. Of the client-owned cats, 42.4% (95% confidence interval (CI): 40.1-44.6) had a positive true infection status. This was higher (56.3% (95% CI: 53.2-59.6)) in cats with outside access than in those without (22.1% (95% CI: 18.9-25.4)). In the first model, the factors age (P < 0.0001), gender (male: P = 0.046), and outside access (P < 0.0001) were independently associated with significantly higher OD405 values. In the second model, the probability of having a positive true infection status increased with age (P < 0.0001), was higher with outside access (P < 0.0001) and in outdoor male cats (P = 0.0006).

Mycobacterium microti: Not Just a Coincidental Pathogen for Cats.

Public interest in animal tuberculosis is mainly focused on prevention and eradication of bovine tuberculosis in cattle and wildlife. In cattle, immunodiagnostic tests such as the tuberculin skin test or the interferon gamma (IFN-γ) assay have been established and are commercially available. Feline tuberculosis is rather unknown, and the available diagnostic tools are limited. However, infections with Mycobacterium tuberculosis complex members need to be considered an aetiological differential diagnosis in cats with granulomatous lymphadenopathy or skin nodules and, due to the zoonotic potential, a time-efficient and accurate diagnostic approach is required. The present study describes 11 independent cases of Mycobacterium microti infection in domestic cats in Switzerland. For three cases, clinical presentation, diagnostic imaging, bacteriological results, immunodiagnostic testing, and pathological features are reported. An adapted feline IFN-γ release assay was successfully applied in two cases and appears to be a promising tool for the ante mortem diagnosis of tuberculosis in cats. Direct contact with M. microti reservoir hosts was suspected to be the origin of infection in all three cases. However, there was no evidence of M. microti infection in 346 trapped wild mice from a presumptive endemic region. Therefore, the source and modalities of infection in cats in Switzerland remain to be further elucidated.

Molecular characterization and virus neutralization patterns of severe, non-epizootic forms of feline calicivirus infections resembling virulent systemic disease in cats in Switzerland and in Liechtenstein.

Feline calicivirus (FCV) infections are associated with oral ulceration, chronic stomatitis and a limping syndrome. Epizootic outbreaks of virulent systemic disease (VSD) have been reported in the USA and Europe. Here, the molecular characterization and neutralization patterns of FCV isolates from cases of severe, non-epizootic infection associated with skin ulceration and edema are presented. Samples from eleven symptomatic cats, four in-contact cats and 27 cats with no contact with symptomatic cats were collected and tested for FCV, feline herpesvirus-1 (FHV-1), feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV). Phylogenetic analyses based on the capsid (VP1) gene of FCV and virus neutralization with antisera raised against four FCV vaccine strains were performed. Nine kittens and two adult cats in two shelters and two veterinary clinics in four geographically distinct locations in Switzerland and Liechtenstein were affected. The cats showed fever, tongue and skin ulceration, head and paw edema, and occasionally jaundice, generalized edema and dyspnea. All symptomatic cats tested FCV-positive but were negative for FHV-1, FeLV and FIV, with the exception of one FIV-positive kitten. All kittens of one litter and both adult cats died. The disease did not spread to cats in the environment. Cats in the environment displayed phylogenetically distinct, but related, FCV strains. Virus neutralization patterns suggested that some cases might have been potentially prevented by vaccination with the optimal vaccine strain. In conclusion, clinicians should be aware of severe, non-epizootic forms of FCV infections with initial clinical presentations similar to VSD.

Retroviral DNA--the silent winner: blood transfusion containing latent feline leukemia provirus causes infection and disease in naïve recipient cats.

BACKGROUND: The feline leukemia virus (FeLV) is a gamma-retrovirus of domestic cats that was discovered half a century ago. Cats that are infected with FeLV may develop a progressive infection resulting in persistent viremia, immunodeficiency, tumors, anemia and death. A significant number of cats mount a protective immune response that suppresses viremia; these cats develop a regressive infection characterized by the absence of viral replication and the presence of low levels of proviral DNA. The biological importance of these latter provirus carriers is largely unknown. RESULTS: Here, we demonstrate that ten cats that received a transfusion of blood from aviremic provirus carriers developed active FeLV infections, some with a progressive outcome and the development of fatal FeLV-associated disease. The infection outcome, disease spectrum and evolution into FeLV-C in one cat mirrored those of natural infection. Two cats developed persistent antigenemia; six cats were transiently antigenemic. Reactivation of infection occurred in some cats. One recipient developed non-regenerative anemia associated with FeLV-C, and four others developed a T-cell lymphoma, one with secondary lymphoblastic leukemia. Five of the ten recipient cats received provirus-positive aviremic blood, whereas the other five received provirus- and viral RNA-positive but aviremic blood. Notably, the cats that received blood containing only proviral DNA exhibited a later onset but graver outcome of FeLV infection than the cats that were transfused with blood containing proviral DNA and viral RNA. Leukocyte counts and cytokine analyses indicated that the immune system of the latter cats reacted quicker and more efficiently. CONCLUSIONS: Our results underline the biological and epidemiological relevance of FeLV provirus carriers and the risk of inadvertent FeLV transmission via blood transfusion and demonstrate the replication capacity of proviral DNA if uncontrolled by the immune system. Our results have implications not only for veterinary medicine, such as the requirement for testing blood donors and blood products for FeLV provirus by sensitive polymerase chain reaction, but are also of general interest by revealing the importance of latent retroviral DNA in infected hosts. When aiming to eliminate a retroviral infection from a population, provirus carriers must be considered.

Evaluation of the effect of short-term treatment with the integrase inhibitor raltegravir (Isentress) on the course of progressive feline leukemia virus infection.

Cats persistently infected with the gammaretrovirus feline leukemia virus (FeLV) are at risk to die within months to years from FeLV-associated disease, such as immunosuppression, anemia or lymphoma/leukemia. The integrase inhibitor raltegravir has been demonstrated to reduce FeLV replication in vitro. The aim of the present study was to investigate raltegravir in vivo for its safety and efficacy to suppress FeLV replication. The safety was tested in three naïve specified pathogen-free (SPF) cats during a 15 weeks treatment period (initially 20mg then 40mg orally b.i.d.). No adverse effects were noted. The efficacy was tested in seven persistently FeLV-infected SPF cats attained from 18 cats experimentally exposed to FeLV-A/Glasgow-1. The seven cats were treated during nine weeks (40mg then 80mg b.i.d.). Raltegravir was well tolerated even at the higher dose. A significant decrease in plasma viral RNA loads (∼5×) was found; however, after treatment termination a rebound effect was observed. Only one cat developed anti-FeLV antibodies and viral RNA loads remained decreased after treatment termination. Of note, one of the untreated FeLV-A infected cats developed fatal FeLV-C associated anemia within 5 weeks of FeLV-A infection. Moreover, progressive FeLV infection was associated with significantly lower enFeLV loads prior to infection supporting that FeLV susceptibility may be related to the genetic background of the cat. Overall, our data demonstrate the ability of raltegravir to reduce viral replication also in vivo. However, no complete control of viremia was achieved. Further investigations are needed to find an optimized treatment against FeLV. (250 words).

Surveillance using serological and molecular methods for the detection of infectious agents in captive Brazilian neotropic and exotic felids.

The aim of the current study was to investigate the exposure of captive wild felids to various infectious pathogens using serological and molecular methods. One hundred and fifty-nine neotropic felids and 51 exotic felids from 28 captive settings in Brazil were tested. While antibodies against Feline parvovirus and Feline coronavirus (FCoV), Feline calicivirus and Bartonella spp. were frequently detected by serologic tests, antibodies against Felid herpesvirus 1 or infection with hemotropic mycoplasmas were less prevalent. Serologic evidence of exposure to Ehrlichia spp., Feline immunodeficiency virus, and Feline leukemia virus (FeLV) was detected rarely, and infections with FeLV, Ehrlichia spp., and Cytauxzoon spp. were found infrequently. The detected Bartonella sequence was molecularly similar to B. koehlerae and B. henselae; for Cytauxzoon, the sequence resembled those from domestic cats. No Anaplasma phagocytophilum and Theileria spp. infections were detected. The positive test results varied significantly among different facilities and species. Additionally, FCoV seropositivity was more prevalent in captivity than in free-ranging populations. Results suggest that testing is appropriate prior to relocation of felids.

Rectal duplication cyst in a cat.

Enteric duplication is a rare developmental malformation in people, dogs and cats. The purpose of the present report is to describe the first case of a rectal duplication cyst in a 7-year-old domestic shorthair cat presenting for acute constipation and tenesmus. On rectal palpation a spherical mass compressing the lumen of the rectum could be felt in the dorsal wall of the rectum. A computed tomography (CT) scan confirmed the presence of a well demarcated cystic lesion in the pelvic canal, dorsal to the rectum. The cyst was surgically removed via a perineal approach. No communication with the rectal lumen could be demonstrated. Histopathological examination was consistent with a rectal duplication cyst. Clinical signs resolved completely after excision of this conjoined non-communicating cystic rectal duplicate.

Development and application of a universal Hemoplasma screening assay based on the SYBR green PCR principle.

Hemotropic mycoplasmas (hemoplasmas) are the causative agents of infectious anemia in several mammalian species. Their zoonotic potential has recently been substantiated by the identification of a feline hemoplasma isolate in an immunocompromised human patient. Although species-specific diagnostic molecular methods have been developed, their application as screening tools is limited due to the species diversity of hemoplasmas. The goals of this study were to develop a universal hemoplasma screening assay with broad specificity based on the SYBR green PCR principle, to compare the assay with hemoplasma-specific TaqMan PCR, and to analyze potential tick vectors and human blood samples to address the zoonotic potential. The newly developed PCR assay based on the 16S rRNA gene amplified feline, canine, bovine, porcine, camelid, and murine hemoplasmas, as well as Mycoplasma penetrans and Mycoplasma pneumoniae. The lower detection limit for feline and canine hemoplasmas was 1 to 10 copies/PCR. The assay exhibited 98.2% diagnostic sensitivity and 92.1% diagnostic specificity for feline hemoplasmas. All 1,950 Ixodes ticks were PCR negative, suggesting that Ixodes ticks are not relevant vectors for the above-mentioned hemoplasma species in Switzerland. None of the 414 blood samples derived from anemic or immunocompromised human patients revealed a clear positive result. The SYBR green PCR assay described here is a suitable tool to screen for known and so-far-undiscovered hemoplasma species. Positive results should be confirmed by specific TaqMan PCR or sequencing.

Feline leukemia virus and other pathogens as important threats to the survival of the critically endangered Iberian lynx (Lynx pardinus).

BACKGROUND: The Iberian lynx (Lynx pardinus) is considered the most endangered felid species in the world. In order to save this species, the Spanish authorities implemented a captive breeding program recruiting lynxes from the wild. In this context, a retrospective survey on prevalence of selected feline pathogens in free-ranging lynxes was initiated. METHODOLOGY/ PRINCIPAL FINDINGS: We systematically analyzed the prevalence and importance of seven viral, one protozoan (Cytauxzoon felis), and several bacterial (e.g., hemotropic mycoplasma) infections in 77 of approximately 200 remaining free-ranging Iberian lynxes of the Doñana and Sierra Morena areas, in Southern Spain, between 2003 and 2007. With the exception of feline immunodeficiency virus (FIV), evidence of infection by all tested feline pathogens was found in Iberian lynxes. Fourteen lynxes were feline leukemia virus (FeLV) provirus-positive; eleven of these were antigenemic (FeLV p27 positive). All 14 animals tested negative for other viral infections. During a six-month period in 2007, six of the provirus-positive antigenemic lynxes died. Infection with FeLV but not with other infectious agents was associated with mortality (p<0.001). Sequencing of the FeLV surface glycoprotein gene revealed a common origin for ten of the eleven samples. The ten sequences were closely related to FeLV-A/61E, originally isolated from cats in the USA. Endogenous FeLV sequences were not detected. CONCLUSIONS/SIGNIFICANCE: It was concluded that the FeLV infection most likely originated from domestic cats invading the lynx's habitats. Data available regarding the time frame, co-infections, and outcome of FeLV-infections suggest that, in contrast to the domestic cat, the FeLV strain affecting the lynxes in 2007 is highly virulent to this species. Our data argue strongly for vaccination of lynxes and domestic cats in and around lynx's habitats in order to prevent further spread of the virus as well as reduction the domestic cat population if the lynx population is to be maintained.

Use of combined conventional and real-time PCR to determine the epidemiology of feline haemoplasma infections in northern Italy.

Although knowledge of feline haemotropic mycoplasmas (haemoplasmas) has dramatically improved in recent years, some issues still remain to be elucidated. The aim of the current study was to evaluate the prevalence of feline haemoplasma infections in blood samples collected from cats in northern Italy. A convenience-sample of 307 cats (40 anaemic; 258 non-anaemic; nine with unknown haematocrit [HCT]) was investigated using polymerase chain reaction assays. Furthermore, the date of blood collection, signalment and clinicopathological data were retrospectively evaluated to assess predictors and risk factors for infection. Haemoplasma infections were highly prevalent in the sample investigated with an overall prevalence of 18.9% (95% confidence interval: 14.5-23.3%). The prevalence for the three feline haemoplasmas was 17.3% for 'Candidatus Mycoplasma haemominutum' (CMhm), 5.9% for Mycoplasma haemofelis (Mhf) and 1.3% for 'Candidatus Mycoplasma turicensis' (CMt). Feline immunodeficiency virus-positive status represented a risk factor for infection with an odds ratio of 4.19 (P=0.02). Moreover, a higher prevalence was observed in summer (odds ratio 1.78; P=0.04) which may be consistent with arthropod-borne disease transmission. Cats infected with Mhf showed significantly lower HCT (P=0.03), haemoglobin values (P=0.02) and red blood cell counts (P=0.04), lower mean corpuscular haemoglobin concentration (P<0.01) and higher white blood cell counts (P<0.01) when compared with non-infected cats.

Real-time PCR investigation of feline leukemia virus proviral and viral RNA loads in leukocyte subsets.

Cats exposed to feline leukemia virus (FeLV), a naturally occurring gammaretrovirus develop either progressive or regressive infection. Recent studies using analyses with enhanced sensitivity have correlated loads throughout FeLV with the clinical outcome, though remarkably, during the acute phase of infection, proviral and viral RNA burdens in the peripheral blood do not differ between groups. We hypothesized that viral loads in specific leukocyte subsets influence the infection outcome. Using a method established to determine the proviral and cell-associated viral RNA loads in specific leukocyte subsets, we evaluated viral loads in eleven FeLV-exposed specific pathogen-free (SPF) cats 2.5 years post-infection. Six cats had undergone regressive infection whereas five were persistently viremic. Aviremic cats had lower total proviral blood loads than the persistently infected cats and FeLV proviral DNA was shown to be integrated into genomic DNA in four out of four animals. Lymphocytes were predominantly infected vs. moncytes and granulocytes in aviremic cats. In contrast, persistently viremic cats were provirus-positive in all leukocyte subsets. The acute phase kinetics of FeLV infection were analyzed in two additional cats; an early lymphoreticular phase with productive infection in lymphocytes in both cats and in monocytes in one cat was followed by infection of the granulocytes; both cats became persistently infected. These results indicate that FeLV persistent viremia is associated with secondary viremia of bone marrow origin, whereas regressive cats only sustain a non-productive infection in low numbers of lymphocytes.

Quantification of endogenous and exogenous feline leukemia virus sequences by real-time PCR assays.

Endogenous retroviruses are integrated in the genome of most vertebrates. They represent footprints of ancient retroviral infection and are vertically transmitted from parents to their offspring. In the genome of all domestic cats, sequences closely related to exogenous FeLV known as endogenous feline leukemia virus (enFeLV), are present. enFeLV are incapable of giving rise to infectious virus particles. However, transcription and translation of enFeLV have been demonstrated in tissues of healthy cats and in feline cell lines. The presence of enFeLV-env has been shown in specific embryonic tissues and adult thymic cells. In addition, the enFeLV-env region recombines with FeLV subgroup A giving rise to an infectious FeLV-B virus. enFeLV envelope protein, FeLIX (FeLV infectivity X-essory protein) is also involved in mediating FeLV-T infection. In order to test the hypothesis that the enFeLV loads play a role in exogenous FeLV-A infection and pathogenesis, quantitative real-time PCR and RT-PCR assays were developed. An assay, specific to U3 region of all different subtypes of exogenous FeLV, was designed and applied to quantify exogenous FeLV proviral or viral load in cats, while three real-time PCR assays were designed to quantify U3 and env enFeLV loads (two within U3 amplifying different sequences; one within env). enFeLV loads were investigated in blood samples derived from Swiss privately owned domestic cats, specific pathogen-free (SPF) cats and European wildcats (Felis silvestris silvestris). Significant differences in enFeLV loads were observed between privately owned cats and SPF cats as well as among SPF cats originating from different catteries and among domestic cats of different breeds. When privately owned cats were compared, FeLV-infected cats had higher loads than uninfected cats. In addition, wildcats had higher enFeLV loads than domestic cats. In conclusion, the quantitative real-time PCR assays described herein are important prerequisites to quantify enFeLV proviral loads in felids and thus are important tools to investigate the role of enFeLV loads in FeLV infection.

Cellular segregation of feline leukemia provirus and viral RNA in leukocyte subsets of long-term experimentally infected cats.

Cats exposed to feline leukemia virus (FeLV) may develop different outcomes of the infection. However, during acute infection blood proviral and viral RNA loads of cats with progressive and regressive infection are not significantly different. Thus, not the overall loads but rather those of specific leukocyte subsets may influence the infection outcome. By combining fluorescence activated cell sorting (FACS) with sensitive real-time TaqMan PCR and reverse transcriptase (RT) PCR, we established in the present study the methods to determine FeLV proviral and viral RNA loads in specific leukocyte subsets. In addition, they were applied to analyze long-term persistently FeLV-infected (p27-positive) and FeLV exposed but nonantigenemic (p27-negative), nonviremic cats. In the latter animals, CD4(+) and B lymphocytes exhibited the highest proviral loads, whereas in p27-positive cats, all leukocyte subsets showed similar high loads. In p27-positive cats, monocytes and granulocytes bore the highest viral RNA loads, whereas only one p27-negative cat was positive for viral RNA in T lymphocytes. To our knowledge, this is the first study to investigate FeLV proviral and viral RNA loads in leukocyte subsets of FeLV exposed cats. The herein described methods are important prerequisites to gain a deeper insight into the pathogenesis of FeLV infection.

Copy number polymorphism of endogenous feline leukemia virus-like sequences.

In the cat genome, endogenous feline leukemia virus (enFeLV) exists as multiple, nearly full-length proviral sequences. Even though no infectious virus is produced from enFeLV sequences, transcription and translation have been demonstrated in tissues of healthy cats and in feline cell lines. To test the hypothesis that the enFeLV loads play a role in exogenous FeLV-A infection and pathogenesis, we designed three real-time PCR assays to quantify U3 and env enFeLV loads (two within U3 amplifying different sequences; one within env). Applying these assays, we investigated the loads in blood samples derived from Swiss privately owned domestic cats, specific pathogen-free (SPF) cats and European wildcats (Felis silvestris silvestris). Significant differences in enFeLV loads were observed between privately owned cats and SPF cats as well as among SPF cats originating from different catteries and among domestic cats of different breeds. Within privately owned cats, FeLV-infected cats had higher loads than uninfected cats. In addition, higher enFeLV loads were found in wildcats compared to domestic cats. The assays described herein are important prerequisites to quantify enFeLV loads and thus to investigate the influence of enFeLV loads on the course of FeLV infection.

Worldwide occurrence of feline hemoplasma infections in wild felid species.

While hemoplasma infections in domestic cats are well studied, almost no information is available on their occurrence in wild felids. The aims of the present study were to investigate wild felid species as possible reservoirs of feline hemoplasmas and the molecular characterization of the hemoplasma isolates. Blood samples from the following 257 wild felids were analyzed: 35 Iberian lynxes from Spain, 36 Eurasian lynxes from Switzerland, 31 European wildcats from France, 45 lions from Tanzania, and 110 Brazilian wild felids, including 12 wild felid species kept in zoos and one free-ranging ocelot. Using real-time PCR, feline hemoplasmas were detected in samples of the following species: Iberian lynx, Eurasian lynx, European wildcat, lion, puma, oncilla, Geoffroy's cat, margay, and ocelot. "Candidatus Mycoplasma haemominutum" was the most common feline hemoplasma in Iberian lynxes, Eurasian lynxes, Serengeti lions, and Brazilian wild felids, whereas "Candidatus Mycoplasma turicensis" was the most prevalent in European wildcats; hemoplasma coinfections were frequently observed. Hemoplasma infection was associated with species and free-ranging status of the felids in all animals and with feline leukemia virus provirus-positive status in European wildcats. Phylogenetic analyses of the 16S rRNA and the partial RNase P gene revealed that most hemoplasma isolates exhibit high sequence identities to domestic cat-derived isolates, although some isolates form different subclusters within the phylogenetic tree. In conclusion, 9 out of 15 wild felid species from three different continents were found to be infected with feline hemoplasmas. The effect of feline hemoplasma infections on wild felid populations needs to be further investigated.

Vaccination against the feline leukaemia virus: outcome and response categories and long-term follow-up.

Feline leukaemia virus (FeLV) is a pathogen inducing fatal disease in cats worldwide. By applying sensitive molecular assays, efficacious commonly used FeLV vaccines that protect cats from antigenaemia were found not to prevent proviral integration and minimal viral replication after challenge. Nonetheless, vaccines protected cats from FeLV-associated disease and prolonged life expectancy. The spectrum of host response categories was refined by investigating plasma viral RNA loads. All cats initially fought similar virus loads, although subsequently loads were associated with infection outcomes. Persistence of plasma viral RNA was moderately associated with reactivation of FeLV infection. In conclusion, sensitive molecular assays are important tools for reviewing pathogenesis of FeLV infection.

Prevalence, risk factor analysis, and follow-up of infections caused by three feline hemoplasma species in cats in Switzerland.

Recently, a third novel feline hemotropic Mycoplasma sp. (aka hemoplasma), "Candidatus Mycoplasma turicensis," in a cat with hemolytic anemia has been described. This is the first study to investigate the prevalence, clinical manifestations, and risk factors for all three feline hemoplasma infections in a sample of 713 healthy and ill Swiss cats using newly designed quantitative real-time PCR assays. "Candidatus Mycoplasma haemominutum" infection was detected in 7.0% and 8.7% and Mycoplasma haemofelis was detected in 2.3% and 0.2% of healthy and ill cats, respectively. "Candidatus Mycoplasma turicensis" was only detected in six ill cats (1.1%); three of them were coinfected with "Candidatus Mycoplasma haemominutum." The 16S rRNA gene sequence of 12 Swiss hemoplasma isolates revealed >98% similarity with previously published sequences. Hemoplasma infection was associated with male gender, outdoor access, and old age but not with retrovirus infection and was more frequent in certain areas of Switzerland. "Candidatus Mycoplasma haemominutum"-infected ill cats were more frequently diagnosed with renal insufficiency and exhibited higher renal blood parameters than uninfected ill cats. No correlation between hemoplasma load and packed cell volume was found, although several hemoplasma-infected cats, some coinfected with feline immunodeficiency virus or feline leukemia virus, showed hemolytic anemia. High M. haemofelis loads (>9 x 10(5) copies/ml blood) seem to lead to anemia in acutely infected cats but not in recovered long-term carriers. A repeated evaluation of 17 cats documented that the infection was acquired in one case by blood transfusion and that there were important differences among species regarding whether or not antibiotic administration led to the resolution of bacteremia.

Reassessment of feline leukaemia virus (FeLV) vaccines with novel sensitive molecular assays.

We previously described antigen negative, provirus positive cats. Subsequently, we hypothesized that efficacious FeLV vaccines cannot prevent minimal viral replication. Thus, we vaccinated cats with either a canarypox-vectored live or a killed virus vaccine and analyzed the challenge outcome with quantitative PCR and a newly established real-time RT-PCR. When judged by conventional parameters (antigenaemia, virus isolation), most of the vaccinated cats were, as expected, protected from persistent viraemia. However, all cats were found to be plasma viral RNA positive. The loads were significantly associated with the infection outcome. Thus, commonly used FeLV vaccines understood to be successful model antiretroviral vaccines protecting against FeLV-related diseases do not confer sterilizing immunity.