Dual-subtype vaccine (Fel-O-Vax FIV) protects cats against contact challenge with heterologous subtype B FIV infected cats

Fel-O-Vax FIV is a dual-subtype vaccine consisting of inactivated whole viruses of subtype A (Petaluma strain) and subtype D (Shizuoka strain). The efficacy of this vaccine against heterologous subtype A strain challenge was demonstrated, but it is unclear whether the result reflects efficacy in the field. In this study, we evaluated the efficacy of this vaccine against contact challenge by exposing both vaccinated and unvaccinated control animals with cats infected with Aomori-2 strain belonging to subtype B, a subtype prevalent in many regions of the world. Nineteen specific-pathogen-free (SPF) cats were divided into a vaccinated group (six cats), an unvaccinated control group (eight cats), and a challenge group (five cats), and maintained in the same room. Cats were monitored for FIV proviral DNA by nested PCR and for FIV-specific antibody levels by ELISA. After 1 year of commingling, each cat in the vaccinated group was given a booster dose. In addition, the original challenge group was removed and replaced with another challenge group of SPF cats, which were inoculated with the Aomori-2 strain. FIV infection was confirmed in four of the eight animals in the unvaccinated control group by the 29th week in the second year of commingling. In contrast, all of the animals were negative in the vaccinated group. These findings confirmed the efficacy of this vaccine against heterologous stains classified as subtype B, and suggested that the vaccine exhibits broad efficacy against genetically diverse FIV.     

Differentiation of feline immunodeficiency virus vaccination, infection, or vaccination and infection in cats

BACKGROUND: Serodiagnosis of feline immunodeficiency virus (FIV) is complicated by the use of a formalin-inactivated whole-virus FIV vaccine. Cats respond to immunization with antibodies indistinguishable from those produced during natural infection by currently available diagnostic tests, which are unable to distinguish cats that are vaccinated against FIV, infected with FIV, or both. HYPOTHESIS: An enzyme-linked immunosorbent assay (ELISA) detecting antibodies against formalin-treated FIV whole virus and untreated transmembrane peptide will distinguish uninfected from infected cats, regardless of vaccination status. ANIMALS: Blood samples were evaluated from uninfected unvaccinated cats (n = 73 samples), uninfected FIV-vaccinated cats (n = 89), and FIV-infected cats (n = 102, including 3 from cats that were also vaccinated). METHODS: The true status of each sample was determined by virus isolation. Plasma samples were tested for FIV antibodies by a commercial FIV diagnostic assay and an experimental discriminant ELISA. RESULTS: All samples from uninfected cats were correctly identified by the discriminant ELISA (specificity 100%). Of the samples collected from FIV-infected cats, 99 were correctly identified as FIV-infected (sensitivity 97.1%). CONCLUSIONS AND CLINICAL IMPORTANCE: With the exception of viral isolation, the discriminant ELISA is the most reliable assay for diagnosis of FIV. A practical strategy for the diagnosis of FIV infection would be to use existing commercial FIV antibody assays as screening tests. Negative results with commercial assays are highly reliable predictors for lack of infection. Positive results can be confirmed with the discriminant ELISA. If the discriminant ELISA is negative, the cat is probably vaccinated against FIV but not infected. Positive results are likely to represent infection.     

Effect of vaccination against feline immunodeficiency virus on results of serologic testing in cats

OBJECTIVE: To determine the effect of vaccination against FIV on results of serologic assays for FIV infection. DESIGN: Prospective clinical trial. ANIMALS: 26 specific-pathogen-free cats, 102 laboratory-reared cats (42 unvaccinated and uninfected, 41 vaccinated and uninfected, and 19 infected with FIV), and 22 client-owned cats infected with FIV. PROCEDURE: To determine the onset and duration of anti-FIV antibody production in cats following vaccination with a whole-virus vaccine, serum was obtained from the 26 specific-pathogen-free cats prior to vaccination and weekly for 10 weeks, then monthly for 52 weeks, after vaccination; serum was tested for anti-FIV antibodies with lateral flow and microwell plate ELISAs. To determine the diagnostic performance of serologic assays for FIV infection, plasma from uninfected, unvaccinated cats; uninfected, vaccinated cats; and FIV-infected cats was tested for FIV antibodies with the 2 ELISAs, a western blot assay, and an immunofluorescence antibody assay and for FIV antigen with an ELISA. RESULTS: Anti-FIV antibodies were detected in all 26 vaccinated cats 1 year after vaccination. Sensitivity of the antibody assays for FIV infection was high (98% to 100%). Specificity was high in unvaccinated cats (90% to 100%) but poor in vaccinated cats (0% to 54%). None of the vaccinated or infected cats had detectable FIV antigen in plasma. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that vaccination against FIV causes false-positive results for at least 1 year with currently available serologic assays for FIV infection. Negative FIV antibody assay results are highly reliable for detection of uninfected cats, but positive results should be interpreted with caution.     

Efficacy and safety of a feline immunodeficiency virus vaccine

Fel-O-Vax FIV is an inactivated virus vaccine designed as an aid in the prevention of infection of cats, 8 weeks or older, by feline immunodeficiency virus (FIV). It contains two genetically distinct FIV strains. The efficacy of this vaccine was demonstrated in a vaccination-challenge study designed to meet various regulatory requirements for registering the vaccine. Eight-week-old kittens were vaccinated with an immunogenicity vaccine which contained minimal release levels of FIV antigens formulated with a proprietary adjuvant system. Twelve months later, all vaccinates and controls were challenged with a heterologous FIV strain. Following the vigorous challenge exposure, cats were monitored for FIV viremia. It was found that 16% of the vaccinated cats developed viremia while 90% of the controls became persistently infected with FIV, which demonstrated that the vaccine was efficacious and the protective immunity lasted for at least 12 months. The safety of the vaccine was demonstrated by a field safety trial in which only 22 mild reactions of short duration were observed following administering 2051 doses of two pre-licensing serials of Fel-O-Vax FIV to cats of various breeds, ages and vaccination histories. Thus, Fel-O-Vax FIV is safe and efficacious for the prevention of FIV infection in cats.     

Feline immunodeficiency virus status of Australian cats with lymphosarcoma

OBJECTIVE: To determine the FIV status of Australian cats with lymphosarcoma and relate this to patient characteristics, tumour characteristics (tissue involvement, histological grade and immunophenotype), haematological and serum biochemical values and FeLV status of affected cats. DESIGN: Prospective study of 101 client-owned cats with naturally-occurring lymphosarcoma. PROCEDURE: Western blot analysis, ELISA and immunochromatography were used to detect FIV antibodies in serum from cats with lymphosarcoma. RESULTS: On the basis of Western blot analysis (which was considered the most accurate method for determining FIV status), 50/101 (50%) of cats with naturally-occurring lymphosarcoma were positive for FIV antibodies. Of these 50 cats, 35 had tumours of B-cell phenotype, 13 had T-cell tumours and 2 had tumours classified as non-B/non-T. Tumours from eight of these FIV-positive cats contained FeLV gene sequences, including a 9-month-old cat with FeLV antigenaemia. Compared with FlV-negative cats with lymphosarcoma, FIV-positive cats were more likely to be domestic crossbreds (P = 0.004), male (P = 0.048) and have atypical (especially nasal) forms of lymphosarcoma (P = 0.09). Only 39 of 107 (36%) blood or sera tested using ELISA were positive for FIV antibodies (including 5 false-positives). CONCLUSIONS: The prevalence of FIV infection was considerably higher in our cohort of cats compared with series of lymphosarcoma cases from the Northern hemisphere. A positive FIV status was strongly associated with lymphosarcoma in Australian cats and it is possible that this infection may predispose to the development of lymphoid neoplasia. The presence of FIV infection would have been underestimated if commercial kits alone had been used for serology.     

Immunization-induced decrease of the CD4+:CD8+ ratio in cats experimentally infected with feline immunodeficiency virus.

In a previous experiment a group of 15 specified pathogen free (SPF) cats were experimentally infected with a Swiss isolate of feline immunodeficiency virus (FIV). A group of 15 SPF cats served as FIV negative controls. Nine cats of each group were vaccinated with a recombinant feline leukemia virus (FeLV) vaccine, six cats in each group with a placebo vaccine. All vaccinated cats developed high antibody titers to FeLV and were protected against subsequent FeLV challenge infection. In both control groups five of six cats became persistently infected with FeLV. Unexpectedly, the primary immune response to the vaccine antigen was significantly higher in the FIV positive group than in the FIV negative. The secondary response was stronger in the FIV negative cats. The goal of the present investigation was to further study the immune response in these 30 cats. They were immunized twice with the synthetic peptide L-tyrosine-L-glutamic acid-poly(DL-alanine)-poly(L-lysine) (TGAL) 21 days apart. Blood samples were collected on four occasions during the immunization process. They were tested for antibodies to TGAL, complete blood cell counts and CD4+, CD8+ and pan-T-lymphocyte counts. The following observations were made: (1) in contrast to the FeLV vaccine experiment, the primary immune response to TGAL was not significantly stronger in the FIV positive cats when tested by enzyme-linked immunosorbent assay (2). The absolute size of the CD4+ lymphocyte population was distinctly smaller in the FIV positive than in the FIV negative cats. The lowest CD4+ values were found in the dually FIV/FeLV infected cats. (3) A population of CD8+ lymphocytes was identified that was characterized by a distinctly weaker fluorescence. The size of this population increased in FIV positive and decreased in FIV negative cats during the TGAL immunization experiment. (4) The CD4+:CD8+ ratio increased in FIV negative cats during TGAL immunization from 1.9 to 2.3. In contrast, in FIV positive animals the CD4+:CD8+ ratio decreased significantly from 1.9 to 1.3 during the same period. From these and earlier data it was concluded that in short-term FIV infection the immune response to T-cell dependent antigens may be increased over that of the controls. Immune suppression develops gradually with duration of the infection. The significant drop of the CD4+:CD8+ ratio over a 5 week immunization period suggests that antigenic stimulation may accelerate the development of immune suppression in FIV positive cats. If this is a general feature, FIV infection may provide a particularly interesting model for studying the pathogenesis of AIDS.     

Accuracy of polymerase chain reaction assays for diagnosis of feline immunodeficiency virus infection in cats

OBJECTIVE: To determine the sensitivity, specificity, and overall diagnostic accuracy of polymerase chain reaction (PCR) assays offered by commercial diagnostic laboratories for diagnosis of FIV infection in cats. DESIGN: Prospective clinical trial. ANIMALS: 124 cats. PROCEDURE: Blood was collected from cats that were neither infected with nor vaccinated against FIV, uninfected cats that were vaccinated with a licensed FIV vaccine, and cats experimentally and naturally infected with FIV representing subtypes A, B, and C. Coded blood samples were submitted to 3 laboratories in the United States and Canada offering PCR assays for diagnosis of FIV infection to veterinary practitioners. All laboratories tested fresh blood samples, and 1 laboratory also tested samples submitted as dried blood smears. The FIV infection status in all cats was confirmed by virus isolation. Sensitivity, specificity, and correct results were calculated for each PCR assay. RESULTS: Sensitivity ranged from 41% to 93%. Specificity ranged from 81% to 100% in unvaccinated cats and 44% to 95% in cats vaccinated against FIV. Correct results were obtained in 58% to 90% of 124 cats tested. All tests misidentified both uninfected and infected cats. False-positive results by all laboratories were higher in cats vaccinated against FIV than in unvaccinated cats, suggesting that vaccination interferes with the performance or interpretation of PCR assays used for diagnosis of FIV infection. CONCLUSIONS AND CLINICAL RELEVANCE: PCR assays used for diagnosis of FIV infection presently marketed to veterinary practitioners in North America vary significantly in diagnostic accuracy and did not resolve the diagnostic dilemma resulting from vaccination of cats against FIV.     

Vaccination of cats experimentally infected with feline immunodeficiency virus, using a recombinant feline leukemia virus vaccine.

A group of 15 cats experimentally infected with a Swiss isolate of feline immunodeficiency virus (FIV) and a group of 15 FIV-negative control cats were inoculated with an FeLV vaccine containing recombinant FeLV-envelope. High ELISA antibody titer developed after vaccination in FIV-positive and FIV-negative cats. Vaccinated and nonvaccinated controls were later challenge exposed by intraperitoneal administration of virulent FeLV subtype A (Glasgow). Although 12 of 12 nonvaccinated controls became infected with FeLV (10 persistently, 2 transiently), only 1 of 18 vaccinated (9 FIV positive, 9 FIV negative) cats had persistent and 2 of 18 had transient viremia. From these data and other observations, 2 conclusions were drawn: In the early phase of FIV infection, the immune system is not depressed appreciably, and therefore, cats may be successfully immunized; a recombinant FeLV vaccine was efficacious in protecting cats against intraperitoneal challenge exposure with FeLV.     

Using CF0218-ELISA to distinguish Chlamydophila felis-infected cats from vaccinated and uninfected domestic cats

Chlamydophila felis is a causative agent of acute and chronic conjunctivitis and pneumonia in cats. Cats can be vaccinated with killed or attenuated C. felis. However, current serodiagnostics cannot distinguish these cats from naturally infected cats. This causes difficulty of early diagnosis and seroepidemiological survey for C. felis. We previously reported that C. felis CF0218 can be used as a C. felis-infection-specific diagnostic antigen in experimentally infected and/or vaccinated cats. In this study, we evaluated an enzyme-linked immunosorbent assay using recombinant CF0218 as antigen (CF0218-ELISA) to detect anti-C. felis antibody in 714 sera of domestic cats whose histories of vaccination against C. felis are known. The 44 vaccinated cats were 93% negative using CF0218-ELISA; half of these scored positive by immunofluorescence assay (IFA) using C. felis-infected cells as antigen. The 670 non-vaccinated cats had CF0218-ELISA positivity rates that were statistically in agreement with IFA (18% vs. 21%). These results show that CF0218, which was identified as a C. felis-infection-specific antigen, is a useful serodiagnostic antigen to distinguish naturally C. felis-infected cats from vaccinated and non-infected cats.     

A survey of FIV antibodies and FeLV antigens in free-roaming cats in the capital area of Finland.

Feline immunodeficiency virus (FIV) was first isolated and identified in 1986. Since then it has been shown to have a worldwide distribution, and the infection generally appears to have reached a state of endemicity. This is the 1st study of FIV-prevalence in Finland. Serum samples of 196 free-roaming cats were tested for antibodies to FIV and FeLV antigens (Feline leukemia virus). With a combined enzyme-linked immunosorbent assay (ELISA), 13 of the cats (6.6%) turned out to be positive for FIV and 2 for FeLV (1.0%). Adult male cats in the capital area of Finland had a FIV prevalence of 24%, a relative proportion 4.7 times higher than that for females.     

Serological survey of Toxoplasma gondii, Dirofilaria immitis, Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) infections in pet cats in Bangkok and vicinities, Thailand

The seroprevalence of Toxoplasma gondii, Dirofilaria immitis (heartworm), feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) infections was examined using serum or plasma samples from 746 pet cats collected between May and July 2009 from clinics and hospitals located in and around Bangkok, Thailand. The samples were tested for heartworm, FIV, and FeLV using a commercial ELISA. Of the 746 samples, 4.6% (34/746) were positive for heartworm antigen, 24.5% (183/746) had circulating FeLV antigen, and 20.1% (150/746) had antibodies against FIV. In addition, the first 348 submitted samples were tested for T. gondii antibodies using a modified agglutination test (MAT, cut off 1:25); 10.1% (35/348) were seropositive. Of the 348 cats sampled for all four pathogens, 11, 10, and 1 were positive for T. gondii antibodies and FIV antibodies, FeLV antigen, or D. immitis antigen, respectively. Of the 35 T. gondii-seropositive cats, 42.9% (15/35) were co-infected with at least one of the other three pathogens. The presence of antibodies to FIV was significantly associated with both age and gender, while FeLV antigen presence was only associated with age. In the case of FIV, males were twice as likely to be infected as females, and cats over 10 years of age were 13.5 times more likely to be infected than cats less than 1 year of age. FeLV antigen was more common in younger cats, with cats over 10 years of age being 10 times less likely to be FeLV positive than cats under 1 year of age. This is the first survey for these four pathogens affecting feline health in Thailand.     

Feline immunodeficiency virus, feline leukaemia virus, Toxoplasma gondii, and intestinal parasitic infections in Taiwanese cats

A population consisting of 70 breeder cats, 43 clinical cases, and 16 feral cats was examined for the presence of Toxoplasma gondii, feline immunodeficiency virus (FIV), and feline leukaemia virus (FeLV). No oocysts of T. gondii were observed in 96 faecal samples; faecal samples were not available from the feral cats. Other intestinal parasites identified included Isospora felis (three cats), Isospora rivolta (five), Dipylidium canium (two), Toxocara cati (four), Toxascaris leonina (one), and Ancylostoma sp. (two). Using a kinetics-based enzyme-linked immunosorbent assay on 117 sera including all the feral cats, nine had antibody to T. gondii antigen, three for antigens to FIV, and seven to the p27 antigen of FeLV. Of the nine cats with antibody to T. gondii, only one was also infected with FIV.     

Prevalence of feline immunodeficiency virus and other retroviral infections in sick cats in Italy.

Two hundred and seventy-seven sick pet cats living in Italy were tested for antibodies to feline immunodeficiency virus (FIV) and for feline leukemia virus (FeLV) antigen. Overall, 24% of the cats resulted positive for anti-FIV antibody and 18% for FeLV antigen. FIV was isolated from the peripheral mononuclear blood cells of ten out of 15 seropositive cats examined and from one out of eight saliva samples. No FIV isolations were obtained from six serum samples cultured. Feline syncytium forming virus (FeSFV) could be isolated from blood and/or saliva in ten out of 11 FIV seropositive cats examined, in six out of nine FeLV antigen positive cats, in two cats found positive for both infection markers, and in three out of 11 cats negative for both markers. Thus, the probability of isolating FeSFV was enhanced by infection with other exogenous retroviruses.     

A prospective epidemiological,clinical, and clinicopathologic study of feline leukemia virus and feline immunodeficiency virus infection in 435 cats from Greece

Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are retroviruses causing significant morbidity and mortality in cats. The aim of this study was to describe the epidemiological, clinical and clinicopathologic aspects of FeLV and FIV infections in different populations of cats in Greece, including client-owned cats, stray cats and cats who live in catteries.A total of 435 cats were prospectively enrolled. Serological detection of FeLV antigen and FIV antibody was performed using a commercial in-house ELISA test kit.The results showed that 17 (3.9 %) and 40 (9.2 %) of the 435 cats were positive for FeLV antigen and FIV antibody, respectively, whereas 5 (1.1 %) had concurrent infection with FeLV and FIV. Factors that were associated with FeLV antigenemia, based on multivariate analysis, included vomiting, rhinitis, infection with FIV, neutropenia, decreased blood urea nitrogen and increased serum cholesterol and triglyceride concentrations. Factors associated with FIV seropositivity included male gender, older age, outdoor access, weight loss, fever, gingivostomatitis, skin lesions and/or pruritus and hyperglobulinemia.Various clinical signs and laboratory abnormalities were found to be significantly associated with retroviral infections, suggesting that current guidelines to test all sick cats should be followed, taking into particular consideration the high-risk groups of cats found in this study.     

Tumor necrosis factor alpha levels in cats experimentally infected with feline immunodeficiency virus: effects of immunization and feline leukemia virus infection.

Tumor necrosis factor alpha (TNF alpha) levels were determined by enzyme-linked immunosorbent assay (ELISA) and by cell culture bioassay in supernatants of lipopolysaccharide-stimulated feline monocyte cultures and in cat serum samples. There was a good correlation between the results obtained by the two methods. From the fact that TNF alpha was neutralized quantitatively by antibodies to human TNF alpha in feline monocyte supernatants and in feline sera, it was concluded that feline TNF alpha immunologically cross-reacts with human TNF alpha and that the human TNF alpha ELISA can be used to quantitate feline TNF alpha. During the first 6 months after experimental feline immunodeficiency virus (FIV) infection no differences in serum TNF alpha values were observed between infected and non-infected cats. TNF alpha levels increased significantly after primary vaccination with a feline leukemia virus (FeLV) vaccine in FIV infected cats over those in the non-infected controls. During secondary immune response TNF alpha levels rose transiently for a period of a few days in both the FIV positive and the FIV negative cats. After FeLV challenge, TNF alpha levels increased in all animals challenged with virulent FeLV for a period of 3 weeks. This period corresponded to the time necessary to develop persistent FeLV viremia in the control cats. It was concluded from these experiments that in the asymptomatic phase of FIV infection no increased levels of TNF alpha are present, similar to the situation in asymptomatic HIV infected humans. Activation of monocytes/macrophages in FIV infected cats by stimuli such as vaccination or FeLV challenge readily leads to increased levels of TNF alpha.     

Serological and molecular evidence of exposure to arthropod-borne organisms in cats from northeastern Spain

One hundred sixty-eight cat sera from Spain were tested for IgG antibodies to Rickettsia conorii (Rc), Ehrlichia canis (Ec), Anaplasma phagocytophilum (Ap) and Bartonella henselae (Bh) antigens using IFA and for FeLV antigen and FIV antibody by ELISA. For 47 whole blood samples, PCR testing was performed for Rickettsia, Ehrlichia and Bartonella. Seroprevalences were: Bh (71.4%), Rc (44%), Ec (11.3%), FeLV (8.5%), FIV (7.4%) and Ap (1.8%). Bh antibodies were associated with seroreactivity to both Ec and Rc antigens. FIV antibodies were associated with illness and cats older than 2 years. Bartonella henselae and B. clarridgeiae (Bcl) DNA was amplified from seven and one sample, respectively.     

Feline immunodeficiency virus diagnosis after vaccination

Prior to the widespread use of vaccination for the control of feline immunodeficiency virus (FIV) infection, diagnosis was made by the detection of antibodies against FIV. A number of commercial animal side tests perform quite well for this determination, with positive predictive values between 91 and 100% and negative predictive values between 96 and 100%. Furthermore, results of these tests could be confirmed by western blot analysis of FIV test-positive sera. Currently, a killed whole virus FIV vaccine has been made available to practitioners. Vaccinated cats seroconvert by ELISA and western blot, making presently available diagnostic tests, which rely on antibody detection, useless in cats after vaccination. The advisory panels of the American Association of Feline Practitioners and Academy of Feline Medicine both recommend testing for feline leukemia virus antigen and FIV antibody before vaccination.     

Persistent upregulation of MHC class II antigen expression on T-lymphocytes from cats experimentally infected with feline immunodeficiency virus.

A significant elevation in the percentage of CD4+ and CD8+ T-lymphocytes expressing major histocompatibility complex (MHC) Class II antigens was observed in the blood of cats shortly after they were experimentally infected with feline immunodeficiency virus (FIV). In addition to an increase in the relative proportion of T-lymphocytes expressing Class II antigens, there was an increase in the density of Class II antigens on the cell surface. These elevations were still evident at the completion of the 5 month study. A second group of cats that had been infected with FIV for almost 5 years, and with either normal or abnormally low levels of CD4+ T-lymphocytes, had similar elevations in MHC II expression, suggesting that such abnormalities are lifelong. Cats with chronic (2 year) feline leukemia virus (FeLV) infection or dual FIV/FeLV infections also showed similar alterations in MHC II expression on CD4+ and CD8+ T-lymphocytes, suggesting that these alterations were not FIV specific. Feline T-lymphocytes expressed more MHC II antigen and interleukin-2 (IL-2) receptor following stimulation in vitro with conconavalin A and IL-2, demonstrating that feline T-lymphocytes respond to activation signals in a manner similar to T-lymphocytes of other species. However, changes in MHC II expression on T-cells of FIV infected cats were not explainable by viral induced T-cell activation alone, because FIV infected cats with elevated MHC II expression did not have coincident elevations in IL-2 receptor expression.     

Prevalence of and factors associated with feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) in cats of the state of Santa Catarina,Brazil

A cross-sectional study was conducted in 274 cats for determination of FeLV antigenemia and FIV seropositivity and factors associated with those infections in cats presented at the Veterinary Hospital of the Santa Catarina State University - UDESC (Brazil). Apparent prevalence for sick cats at the hospital population was 28.41% (95%CI 21.88–34.94%) for FeLV, 7.65% (95%CI 3.71–11.50%) for FIV and 2.18% (95%CI 0.56–5.47%) for both viruses. For healthy cats, the apparent prevalence was 9.89% (95%CI 3.75–16.02%) for FeLV, 2.20% (95%CI 0.34–7.75%) for FIV by immunoassay (ELISA). Average age for FeLV- and FIV-positive individuals was 38.32 and 64.25 months, respectively. Behavior such as aggressiveness and sex (male) were both associated with increased odds of result positivity test for FeLV and FIV; older animals were also associated with FIV test results. A very small proportion of the animals were vaccinated against FeLV and none against FIV. Most of the animals were adopted from shelters or rescued from streets, living with multiple cats that had access to outdoors. The high prevalence of FeLV suggests a need for better control strategies against this disease.     

Diagnosing feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) infection: an update for clinicians

With the commercial release in Australia in 2004 of a vaccine against feline immunodeficiency virus (FIV; Fel‐O‐Vax FIV®), the landscape for FIV diagnostics shifted substantially. Point‐of‐care (PoC) antibody detection kits, which had been the mainstay for diagnosing FIV infection since the early 1990s, were no longer considered accurate to use in FIV‐vaccinated cats, because of the production of vaccine‐induced antibodies that were considered indistinguishable from those produced in natural FIV infections. Consequently, attention shifted to alternative diagnostic methods such as nucleic acid detection. However, over the past 5 years we have published a series of studies emphasising that FIV PoC test kits vary in their methodology, resulting in differing accuracy in FIV‐vaccinated cats. Importantly, we demonstrated that two commercially available FIV antibody test kits (Witness? and Anigen Rapid?) were able to accurately distinguish between FIV‐vaccinated and FIV‐infected cats, concluding that testing with either kit offers an alternative to PCR testing. This review summarises pertinent findings from our work published in a variety of peer‐reviewed research journals to inform veterinarians (particularly veterinarians in Australia, New Zealand and Japan, where the FIV vaccine is currently commercially available) about how the approach to the diagnosis of FIV infection has shifted. Included in this review is our work investigating the performance of three commercially available FIV PoC test kits in FIV‐vaccinated cats and our recommendations for the diagnosis of FIV infection; the effect of primary FIV vaccination (three FIV vaccines, 4 weeks apart) on PoC test kit performance; our recommendations regarding annual testing of FIV‐vaccinated cats to detect ‘vaccine breakthroughs’; and the potential off‐label use of saliva for the diagnosis of FIV infection using some FIV PoC test kits. We also investigated the accuracy of the same three brands of test kits for feline leukaemia virus (FeLV) diagnosis, using both blood and saliva as diagnostic specimens. Based on these results, we discuss our recommendations for confirmatory testing when veterinarians are presented with a positive FeLV PoC test kit result. Finally, we conclude with our results from the largest and most recent FIV and FeLV seroprevalence study conducted in Australia to date.