Feline Panleukopenia Virus Infection Research Articles

Assessing immune evasion potential and vaccine suitability of a feline panleukopenia virus strain

Since the introduction of the feline panleukopenia virus (FPV) vaccine in China in 2011, it has played a crucial role in safeguarding the health of numerous pet cats by preventing FPV infections. However, an observed rise in FPV infections among cats previously vaccinated has prompted our investigation. Our laboratory has identified a specific FPV isolate, FPV-251, which raises concerns about its potential to evade the immune response. To validate this hypothesis, we conducted a correlational study on FPV-251. Ten sera samples were collected from ten cats two months after receiving the vaccine three times. These samples were prepared in the laboratory to assess their ability to neutralize FPV-251. Results indicated that the neutralization titers of the 10 sera ranged from 1:313.7 to 1:1051.0, with an average titer of 1:627.4. Considering the diversity and complexity of clinical practice, we expanded our study to include 86 sera samples collected from cats at the clinic after three-time immunizations. Among these, 8 out of 43 sera collected after one year post three-time immunizations and 5 out of 43 sera collected within one year post three-time immunizations exhibited a neutralization index (NI) of less than 50 against FPV-251. Despite its potential immune evasion capabilities, immunization with inactivated FPV-251 demonstrated effectiveness in providing substantial protection for cats. This was evident from the high levels of sera antibodies against FPV-251 in cats with FPV-251 immunization, as well as their ability to survive and maintain good health after being challenged with FPV-251. Furthermore, sera antibodies from immunized cats displayed the ability to neutralize the other five FPV isolates, indicating a robust cross-protection capacity of the FPV-251 vaccine. Our research findings suggest that although FPV-251 may exhibit certain immune evasion capabilities, it holds significant potential for development into a vaccine to protect pet cats from FPV infection.

Epidemiological and Molecular Approaches for a Fatal Feline Panleukopenia Virus Infection of Captive Siberian Tigers (Panthera tigris altaica) in the Republic of Korea.

Feline panleukopenia virus (FPV), a member of the species Protoparvovirus carnivoran1, is one of the most fatal pathogens of domestic and wild carnivores. The virus endemically infects domestic carnivores worldwide and its cross-species transmission threatens endangered wild carnivores, including Siberian tigers. In this study, a fatal FPV infection in endangered Siberian tigers was investigated to trace the origin of the virus and elucidate the reason behind FPV's infection of the vaccinated tigers. Our genetic characterization and phylogenetic analysis revealed that the virus detected in the infected tigers, designated as the KTPV-2305 strain, was closely related to FPV strains circulating in Korean cats, suggesting that it might have been transmitted from stray cats wandering around the zoo. Compared with the prototype FPV reference strains, the KTPV-2305 strain carried three distinct amino acid (aa) mutations in the VP2 protein sequence (I101T, I232V, and L562V) in this study. These three mutations are commonly found in most global FPV strains, including Korean strains, indicating that these mutations are common evolutionary characteristics of currently circulating global FPVs. The reason why the vaccinated tigers were infected with FPV was most likely the insufficient protective immunity of the affected tigress or vaccine failure triggered by the interference of maternal-derived antibodies in the affected tiger cubs. These findings suggest that improved vaccination guidelines are urgently needed to save the lives of wild carnivores from this fatal virus.

Development and Application of nanoPCR Method for Detection of Feline Panleukopenia Virus.

Feline panleukopenia (FP) is a severe viral illness caused by the feline panleukopenia virus (FPV), putting sectors like companion cat breeding and endangered feline conservation at risk. The virus has a high morbidity and fatality rate and is found all over the world. We created a novel FPV assay using nanoPCR technology and assessed the method's specificity and sensitivity. The approach amplified a 345 bp nucleic acid fragment with a minimum detection limit of 7.97 × 102 copies/μL, which is about 100 times greater than traditional PCR. We collected anal swabs from 83 cats suspected of FPV infection for practical application, and the FPV-positive rate determined by the nanoPCR approach was 77.1%. In conclusion, the approach is more sensitive than conventional PCR and more convenient and cost-effective than qPCR methodology and may be utilized for the clinical detection of FPV.

Transcriptomics analysis reveals key lncRNAs and genes related to the infection of feline kidney cell line by panleukopenia virus

Feline panleukopenia virus (FPV) can cause a viral disease and is responsible for severe leukopenia, gastroenteritis, and nervous signs with significant economic losses. Biochemically long non-coding RNAs (lncRNAs) can regulate the expression of mRNA in different ways, thereby causing the functional changes in host cells in response to viral infection. However, no attention has been paid until now to investigate the link between FPV pathogenesis and lncRNA. Here, through RNA sequencing, we performed a comprehensive analysis of lncRNA and mRNA in F81 cells after FPV-BJ04 strain infection. Consistent with previous studies, our data showed that lncRNAs have distinct features from mRNA. A total of 291 lncRNAs and 873 mRNAs were differentially expressed in F81 cells after FPV-BJ04 infection. GO and KEGG enrichment analysis showed that the differentially upregulated lncRNAs target genes were mainly involved in the positive regulation of transcription by RNA polymerase II and MAPK signaling pathway. The differentially downregulated lncRNAs target genes were mainly involved in the mRNA splicing and endocytosis. In addition, the differentially expressed immune pathway related genes that are targeted by lncRNA were also screened out to construct a lncRNA-miRNA-mRNA axes as a potential novel biomarkers in regulating the immune response of feline against FPV infection. Our results contribute to understand the basic role of lncRNA in F81 cells during FPV infection and lay the foundation for following research.

Detecção do vírus da panleucopenia felina (Carnivore protoparvovirus 1) em Panthera onca de vida livre no Brasil

ABSTRACT: The decline in the jaguar population confirms how much the species is vulnerable to extinction in Brazil. It also indicates the degradation of its natural habitat’s environmental integrity and quality. Studies claim that large felids are susceptible to feline panleukopenia virus (FPV) and are presumptively diagnosed clinically in Brazil. A free-living jaguar (Panthera onca) cub was found unconscious and rescued due to a possible hit-and-run in the savannah of Mato Grosso. During recovery, it exhibited clinical and hematological signs consistent with FPV infection. The PCR was positive for FPV, with 99.61% identity between the FPV sequences available in the GenBank database through the BLAST tool. Due to habitat restrictions, certain diseases threaten wild cats and habitat encroachment by domestic animals can alter the pattern of spread of pathogens. We highlight the importance of the molecular diagnosis and phylogenetic analysis of FPV to elucidate how it has reached wild felids.

Isolation of feline panleukopenia virus from Yanji of China and molecular epidemiology from 2021 to 2022.

Feline panleukopenia virus (FPV) is a widespread and highly infectious pathogen in cats with a high mortality rate. Although Yanji has a developed cat breeding industry, the variation of FPV locally is still unclear. This study aimed to isolate and investigate the epidemiology of FPV in Yanji between 2021 and 2022. A strain of FPV was isolated from F81 cells. Cats suspected of FPV infection (n = 80) between 2021 and 2022 from Yanji were enrolled in this study. The capsid protein 2 (VP2) of FPV was amplified. It was cloned into the pMD-19T vector and transformed into a competent Escherichia coli strain. The positive colonies were analyzed via VP2 Sanger sequencing. A phylogenetic analysis based on a VP2 coding sequence was performed to identify the genetic relationships between the strains. An FPV strain named YBYJ-1 was successfully isolated. The virus diameter was approximately 20-24 nm, 50% tissue culture infectious dose = 1 × 10-4.94/mL, which caused cytopathic effect in F81 cells. The epidemiological survey from 2021 to 2022 showed that 27 of the 80 samples were FPV-positive. Additionally, three strains positive for CPV-2c were unexpectedly found. Phylogenetic analysis showed that most of the 27 FPV strains belonged to the same group, and no mutations were found in the critical amino acids. A local FPV strain named YBYJ-1 was successfully isolated. There was no critical mutation in FPV in Yanji, but some cases with CPV-2c infected cats were identified.

SP1/miR-92a-1–5p/SOCS5: A novel regulatory axis in feline panleukopenia virus replication

MicroRNAs (miRNAs) are vital post-transcriptional regulators that participate in host-pathogen interactions by modulating the expression of cellular factors. Previous studies have demonstrated that feline panleukopenia virus (FPV) alters miRNA expression levels within host cells. However, the relationship between FPV replication and host miRNAs remains unclear. Here, we demonstrated that FPV infection significantly altered cellular miR-92a-1–5p expression in F81 cells by upregulating the expression of specificity protein 1 (SP1). Furthermore, we observed that miR-92a-1–5p enhanced interferon (IFN-α/β) expression by targeting the suppressors of cytokine signaling 5 (SOCS5) that negatively regulates NF-κB signaling and inhibits FPV replication in host cells. These findings revealed that miR-92a-1–5p plays a crucial role in host defense against FPV infection.

Feline Panleukopenia Virus With G299E Substitution in the VP2 Protein First Identified From a Captive Giant Panda in China.

A feline panleukopenia virus (FPV), Giant panda/CD/2018, was isolated from a captive giant panda with mild diarrhea in 2018 in Chengdu, China, and further identified via indirect immunofluorescence assay (IFA), transmission electron microscopy (TEM) observation, and genetic analysis. Phylogenetic analysis based on the complete VP2 nucleotide sequences showed that it shared high homology with Chinese FPV isolates and grouped within FPV cluster 1. One unique substitution Gly(G)299Glu(E) in the capsid protein VP2 was first identified with Giant panda/CD/2018. The presence of the G299E substitution is notable as it is located on the top region of the interconnecting surface loop 3, which may be involved in controlling the host range and antigenicity of FPV. These findings first demonstrate that FPV with natural point mutation G299E in the VP2 gene is prevalent in giant panda and suggest that etiological surveillance and vaccination among all giant pandas are urgently needed to protect this endangered species against FPV infection.

Diagnostic testing for feline panleukopenia in a shelter setting: a prospective, observational study.

ObjectivesThe aim of this study was to optimize the diagnosis of feline panleukopenia virus (FPV) infection in a shelter setting by: (1) comparing the results of the canine parvovirus IDEXX SNAP Parvo (SNAP) point-of-care ELISA with a commercial FPV quantitative real-time PCR (qPCR) test; (2) assessing whether vomit and anal/rectal swabs could be used for early diagnosis; and (3) clarifying the interpretation of weak-positive SNAP test results.MethodsThe study included shelter cats and kittens with incomplete or unknown vaccination history that had clinical signs suspicious for feline panleukopenia and fecal SNAP and PCR tests performed within 24 h of onset. Feces, anal/rectal swabs and vomit were tested using SNAP and PCR, with fecal PCR utilized as the reference standard.ResultsOne hundred and forty-five cats were included. Seventeen were diagnosed with FPV infection and 62 were negative; 66 could not be individually designated because they were co-housed. Sensitivity was as follows: fecal SNAP 55% (n = 102; 95% confidence interval [CI] 32–77); swab SNAP 30% (n = 55; 95% CI 7–65); swab PCR 77% (n = 55; 95% CI 46–95); and vomit PCR 100% (n = 17; 95% CI 16–100). Specificity was high (96–100%) for all sample and test types. For PCR-positive fecal samples, true-positive SNAP tests (including weak positives) had significantly higher DNA viral copy numbers than false-negative SNAP tests (P = 0.0031).Conclusions and relevanceThe SNAP ELISA should be viewed as an initial diagnostic test to rule in feline panleukopenia. Positive fecal SNAP test results, including weak positives, are highly likely to be true positives in clinically affected animals. Negative results in clinically affected animals are unreliable and should be followed up with PCR testing.

Cellular microRNA, miR-1343-5p, modulates IFN-I responses to facilitate feline panleukopenia virus replication by directly targeting IRAK1 gene

Feline panleukopenia is an acute, highly contagious, and fatal infectious disease caused by feline panleukopenia virus (FPV) and has led to severe consequences on pets, economically important animals, and the wildlife industry. MicroRNAs (miRNAs) play significant roles in the host-pathogen interaction by modulating cellular factors expression which are essential for viral replication or host innate immune response to infection. However, the role of host miRNA response in FPV infection remains to be discovered. In this study, we screened nine host miRNAs associated with FPV infection that were previously implicated in innate immunity or antiviral functions. We found that miR-1343-5p overexpression strongly promoted FPV-BJ04 genomic DNA. Subsequently, the expression of host miR-1343-5p was upregulated by FPV-BJ04 infection in vitro and in vivo. In addition, we demonstrated that miR-1343-5p was a negative regulator of the IFN-I signaling pathway, thereby promoting FPV infection. Bioinformatic analysis combined with molecular biological assay indicated that interleukin-1 receptor-associated kinase 1 (IRAK1) is a putative target of miR-1343-5p. Collectively, our findings emphasize the importance of miR-1343-5p in host defense against FPV, thus, enhancing our understanding of its pathogenic mechanism.

Analysis of the microRNA expression profiles in feline kidney cell line infected with feline panleukopenia virus

MicroRNAs (miRNAs) play crucial roles in post-transcriptional regulation of gene expression in many biological processes. Feline panleukopenia virus (FPV) is a highly infectious pathogen that can cause severe disease in pets, economically important animals and wildlife. In this study, miRNAs associated with FPV infection were identified using high-throughput sequencing. Our results showed that 673 known miRNAs and 278 novel miRNAs were identified and 57 significantly differential expression miRNAs were found post-FPV infection in feline kidney cell line. Stem-loop qRT-PCR was applied to validate the expression of the randomly selected miRNAs; the results were consistent with the sequencing data. Furthermore, the target genes of differential expression miRNAs were analyzed and predicated by GO and KEGG pathway. Altogether, our analysis provides a potential link between miRNA expression and the pathogenesis of FPV infection.

Lymphoplasmacytic Meningoencephalitis and Neuronal Necrosis Associated With Parvoviral Infection in Cats.

Neurologic manifestations other than cerebellar hypoplasia are rarely associated with feline panleukopenia virus (FPV) infection in cats. Here the authors describe lymphoplasmacytic meningoencephalitis and neuronal necrosis in 2 cats autopsied after exhibiting ataxia and nystagmus. Gross changes consisted of cerebellar herniation through the foramen magnum, with flattening of cerebrocortical gyri and narrowing of sulci. Histologically, lymphoplasmacytic meningoencephalitis, extensive neuronal necrosis, and neuroaxonal degeneration with digestion chambers were present in the telencephalon and brain stem in both cats. Frozen brain tissue of both cats was positive for parvoviral antigen via fluorescent antibody testing, and formalin-fixed, paraffin-embedded tissue sections of brain were immunoreactive for parvovirus antigen and positive for parvoviral DNA on in situ hybridization. Frozen brain tissue from 1 case was positive for parvovirus NS1 and VP2 genes using conventional polymerase chain reaction, and subsequent DNA sequencing and phylogenetic analysis revealed that the viral strain was a FPV. Reverse transcription quantitative polymerase chain reaction on formalin-fixed, paraffin-embedded brain tissue revealed high levels of parvovirus in both cases, supporting an acute and active viral infection. Although rare, FPV infection should be considered in cases of lymphoplasmacytic meningoencephalitis and neuronal necrosis in cats.

Fulminant Tritrichomonas foetus ‘feline genotype’ infection in a 3-month old kitten associated with viral co-infection

Tritrichomonas foetus is a flagellate protist which commonly causes a waxing and waning large bowel diarrhoea in young cats. We report severe T. foetus infection of the colon, cecum and ileum with concurrent feline enteric coronavirus (FCoV) and feline panleukopenia virus (FPV) in a 3-month-old Bengal kitten with an 8-day history of vomiting, diarrhoea, failure to thrive and coughing. Protozoa filling the lumen and crypts and occasional invading into lamina propria were identified within the affected colon and confirmed by PCR as T. foetus ‘feline genotype’. Assessment of faeces by PCR revealed concurrent infection with FCoV and FPV. It is possible that immunosuppression by FPV played a role in the unprecedented T. foetus infection intensity observed histologically. Studies during and after resolution of FPV infection, will be critical to determine if T. foetus co-infection affects long-term prognosis of FPV survivors.

Survival estimates and outcome predictors for shelter cats with feline panleukopenia virus infection.

OBJECTIVE To determine survival estimates and outcome predictors for shelter cats with feline panleukopenia virus (FPV) infection. DESIGN Retrospective cohort study. ANIMALS 177 shelter cats with FPV infection. PROCEDURES Medical records of cats treated for FPV infection from 2011 through 2013 were reviewed to collect information pertaining to signalment; history; results of physical examination, CBC, serum biochemical analysis, and blood gas analysis; and treatments (antimicrobials, antiparasitics, antivirals, antiemetics, analgesics, crystalloid or colloid solutions, and blood products). Survival time and outcome predictors were determined by means of Kaplan-Meier estimation, logistic regression, and mixed-model ANOVA. RESULTS Median survival time after hospital admission was 3 days; 20.3% (36/177) of cats survived to discharge from the hospital. Risk of nonsurvival was greater in cats with (vs without) signs of lethargy, rectal temperature < 37.9°C (I00.2°F), or low body weight at hospital admission. Lower (vs higher) leukocyte count on days 3,4, and 7 of hospitalization, but not at admission, was associated with nonsurvival. Amoxicillin-clavulanic acid, antiparasitics, and maropitant but not interferon-ω were associated with survival, whereas glucose infusion was associated with nonsurvival. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that FPV infection carried a poor prognosis for shelter cats. Several variables measured at admission or during hospitalization were associated with outcome. Remarkably and contrary to the existing literature, leukopenia at admission had no association with outcome, possibly owing to early prevention of complications.

Study of Histopathological changes associated with FelinePan Leukopenia Virus infection in naturally infected cats

Feline Pan Leukopenia Virus (FPV) was the more serious enteric viral infection of cats at different periods of life. Also had different generalized effects on many vital organs. The current study, aimed to investigate the essential pathological lesions which caused by the virus infection. The study which carried out on 37 infected cats at age range from 3 – 36 months, these cats were checked previously at rapid test and PCR techniques .&#x0D; The autopsy samples were removed from infected animals and study the histopathological changes, including bowel, heart, spleen, tongue, kidney and lung, 10 pieces of each.The results had a significant effect on the animal's life . The histopathological findings were appeared at the level of severe acute infection ,thus lastly caused death. Furthermore, the results revealed that the virus can cause different inflammatory changes at different vital organs .&#x0D; Key Words . Feline parvovirus, Enteritis, histopathology .

Antibody response to feline panleukopenia virus vaccination in healthy adult cats.

According to prior studies, between 25.0% and 92.8% of adult cats have antibodies against feline panleukopenia virus (FPV) and thus are likely protected against FPV infection. It is, however, unknown how healthy adult cats with different antibody titres react to FPV vaccination in the field. Therefore, the aim of the study was to measure antibody titres in healthy adult cats within a period of 28 days after vaccination against FPV and to evaluate factors that are associated with a lack of adequate response to vaccination. One hundred and twelve healthy adult cats were vaccinated with a vaccine against FPV, feline herpesvirus and feline calicivirus. Antibodies against FPV were determined before vaccination (day 0), on day 7 and day 28 after vaccination by haemagglutination inhibition (HI). A HI titre ⩾1:40 was defined as protective. An adequate response to vaccination was defined as a four-fold titre increase. Uni- and multivariate statistical analysis was used to determine factors associated with an adequate response. Pre-vaccination antibody titres of ⩾1:40 were present in 64.3% (72/112; 95% confidence interval [CI] 55.1-72.6). Only 47.3% (53/112; 95% CI 37.8-57.0) of cats had an adequate response to vaccination. Factors associated with an adequate response to vaccination were lack of previous vaccination (odds ratio [OR] 15.58; 95% CI 1.4-179.1; P = 0.035), lack of antibodies (⩾1:40) prior to vaccination (OR 23.10; 95% CI 5.4-98.8; P <0.001) and breed (domestic shorthair cats; OR 7.40; 95% CI 1.4-38.4; P = 0.017). As none of the cats with high pre-vaccination antibody titres (⩾1:160) had an at least four-fold increase in FPV antibody titres, measurement of antibodies rather than regular revaccinations should be performed. Thus, evaluation of FPV antibody titre in cats with previous vaccinations against FPV are recommended prior to revaccination.

Molecular characterisation of parvoviruses from domestic cats reveals emergence of newer variants in India.

Objectives The present study was undertaken to characterise the viral polypeptide 2 (VP2) gene of parvovirus from domestic cats in India. Methods The faecal samples from diarrhoeic/healthy domestic cats were collected from different geographical regions of India for screening by PCR assay followed by sequence analysis of the VP2 gene. Results Canine parvovirus (CPV)/feline panleukopenia virus (FPV) infections were found in 12 (11.3%) of 106 faecal samples tested. Two new CPV-2a (297Ala and Asn426) and three FPV strains were identified by VP2 gene analysis. Several unique and existing amino acid mutations were found, suggesting continuous evolution and emergence of newer variants. The phylogenetic analysis of the CPV sequences revealed that the two new CPV-2a strains from Mumbai (MC8) and Puducherry (P15) were clustered together in a single clade but had evolved independently and were ancestrally related to Chinese CPV-2a isolates. The FPV sequences (T-C-6 and T-C-1) from Thrissur, Kerala, formed a different clade (FPV clade) and were closely related to each other and had an ancestral relationship with an FPV isolate from the USA. Another FPV isolate from Goa (GC1) was positioned in the same clade but had evolved independently. Conclusions and relevance Detection of CPV in both diarrhoeic/healthy cats and the occurrence of FPV infection in a vaccinated cat provide new insights into parvovirus infections in cats in India.

Case series of feline panleukopenia virus in an animal shelter

The aim of this study was to describe a series of confirmed and suspected cases of feline panleukopenia virus (FPV) and in-contact cats in an adoption-guarantee shelter in an FPV-endemic area by reviewing shelter records over a 10-month period (January-October 2010). Cats were divided into three groups: in-contact group - asymptomatic cats that were housed with a FPV fecal antigen (Ag)-positive cat/kitten as part of a litter group (n = 66); FPV-survivors group (FPV-infected survivors) - tested FPV fecal Ag-positive and showed clinical signs of FPV, but survived (n = 27); FPV-non-survivors group (FPV-infected non-survivors) - showed clinical signs of FPV and either tested FPV fecal Ag-positive or were housed with an Ag-positive family member, but did not survive (n = 52). Ages ranged from 3 weeks to 3 years, but most were <6 months old (in-contact group: 79%; FPV-survivors group: 70%; FPV-non-survivors group: 85%). A seasonal peak occurred over summer, but cases occurred year-round. Anorexia, dehydration, fever and diarrhea predominated in the FPV-survivors group, and death was preceded by clinical signs of circulatory shock in the FPV-non-survivors group. Housing litters of kittens with their mother was not associated with improved outcome, perhaps because in this population clinical FPV infection was relatively common in queens arriving at the shelter with susceptible litters.

Canine and feline parvoviruses preferentially recognize the non-human cell surface sialic acid N-glycolylneuraminic acid

Feline panleukopenia virus (FPV) is a pathogen whose canine-adapted form (canine parvovirus (CPV)) emerged in 1978. These viruses infect by binding host transferrin receptor type-1 (TfR), but also hemagglutinate erythrocytes. We show that hemagglutination involves selective recognition of the non-human sialic acid N-glycolylneuraminic acid (Neu5Gc) but not N-acetylneuraminic acid (Neu5Ac), which differs by only one oxygen atom from Neu5Gc. Overexpression of α2-6 sialyltransferase did not change binding, indicating that both α2-3 and α2-6 linkages are recognized. However, Neu5Gc expression on target cells did not enhance CPV or FPV infection in vitro. Thus, the conserved Neu5Gc-binding preference of these viruses likely plays a role in the natural history of the virus in vivo. Further studies must clarify relationships between virus infection and host Neu5Gc expression. As a first step, we show that transcripts of CMAH (which generates Neu5Gc from Neu5Ac) are at very low levels in Western dog breed cells.

Does a Feline Leukemia Virus Infection Pave the Way forBartonella henselaeInfection in Cats?

Domestic cats serve as the reservoir hosts of Bartonella henselae and may develop mild clinical symptoms or none after experimental infection. In humans, B. henselae infection can result in self-limiting cat scratch disease. However, immunocompromised patients may suffer from more-severe courses of infection or may even develop the potentially lethal disease bacillary angiomatosis. It was reasoned that cats with immunocompromising viral infections may react similarly to B. henselae infection. The aim of our study was to investigate the influence of the most important viruses known to cause immunosuppression in cats-Feline leukemia virus (FeLV), Feline immunodeficiency virus (FIV), and Feline panleukopenia virus (FPV)-on natural B. henselae infection in cats. Accordingly, 142 cats from animal shelters were necropsied and tested for B. henselae and concurrent infections with FeLV, FIV, or FPV by PCR and immunohistochemistry. A significant association was found between B. henselae and FeLV infections (P = 0.00028), but not between B. henselae and FIV (P = 1.0) or FPV (P = 0.756) infection, age (P = 0.392), or gender (P = 0.126). The results suggest that susceptibility to B. henselae infection is higher in cats with concurrent FeLV infections, regardless of whether the infection is latent or progressive. Histopathology and immunohistochemistry for B. henselae failed to identify lesions that could be attributed specifically to B. henselae infection. We conclude that the course of natural B. henselae infection in cats does not seem to be influenced by immunosuppressive viral infections in general but that latent FeLV infection may predispose cats to B. henselae infection or persistence.