Determining the feline immunodeficiency virus (FIV) status of FIV-vaccinated cats using point-of-care antibody kits

Global seroprevalence and factors associated with seropositivity for feline immunodeficiency virus (FIV) in cats: A systematic review and meta-analysis

The feline immunodeficiency virus (FIV) is a retrovirus of the Lentivirus genus, distributed worldwide, that causes persistent infection with a significant impact on the cats' health. Due to the importance of this infection in feline medicine, this pioneering study aimed to obtain an integrated estimate of the global seroprevalence of FIV in cats and to characterize the factors associated with this infection. Four electronic databases were screened for observational studies with FIV seroprevalence in cats published globally for this systematic review and meta-analysis. The initial search method returned 873 studies, of which 113 met all predefined criteria and were therefore included in this review. Meta-analysis with general data was performed, and a combined global seropositivity of 9.43 % (95 % CI: 8.24 % - 10.78 %) was found. Seropositivity was 14.34 % (95 % CI = 10.92 % - 18.61 %) in Asia, 11.90 % (95 % CI = 9.82 % - 14.34 %) in Oceania, 10.90 % (95 % CI = 5.71 % - 19.82 %) in Central America, 9.43 % (95 % CI = 6.95 % - 12.66 %) in South America, 9 % (95 % CI = 0 - 80 %) in Africa, 8.98 % (95 % CI = 7.31 % - 10.98 %) in Europe, and 5.93 % (95 % CI = 4.33 % - 8.07 %) in North America. Meta-analysis of factors associated with seropositivity demonstrated that FIV seroprevalence was higher in male (Prevalence ratio [PR] = 2.53, 95 % CI = 2.16 - 2.95), adult (PR = 2.83, 95 % CI = 2.24 - 3.56), unowned status (PR = 1.47, 95 % CI = 1.07 - 2.03), sick status (PR = 2.46, 95 % CI = 1.97 - 3.06), and cats with outdoor access (PR = 4.38, 95 % CI = 2.26 - 8.47). The results demonstrated that FIV is globally distributed and has a high seroprevalence in some geographical areas. Information compiled from this research is relevant to understanding the worldwide epidemiology of FIV. It presents the potential to contribute to the planning of strategies focused on controlling and reducing cases in cat populations.

Detection of feline immunodeficiency virus by neutral red-based loop-mediated isothermal amplification assay

Background and Aim

Feline immunodeficiency virus (FIV) is a retroviral pathogen globally responsible for immunodeficiency disease in cats. However, the current diagnosis based on antibody detection has limitations and can also produce false-positive results. This study aimed to develop a one-pot loop-mediated isothermal amplification (LAMP) process integrated with neutral red (NR-LAMP) assay for detection of FIV proviral DNA.

Materials and Methods

We developed a one-pot, gag gene-based NR-LAMP for convenient, rapid, specific, and sensitive colorimetric inspection of FIV proviral DNA.

Results

The developed NR-LAMP was capable of amplifying at an optimum temperature of 65°C for 40 min. No cross-amplification was detected between FIV and other feline viruses tested, indicating the high specificity (98.44%) of the novel FIV-LAMP primer. Our NR-LAMP assay has a detection limit of 4.2 × 101 copies/μL. A total of 80 clinical samples with a background of FIV infection were collected and tested using the proposed method. The NR-LAMP assay showed a high sensitivity of 100% compared to conventional polymerase chain reaction assay.

Conclusion

These results support the suitability of NR-LAMP as a potential future alternative clinical molecular approach for further use in the diagnosis of FIV-infected cats.

Generation of a Single-Chain Variable Fragment Antibody against Feline Immunoglobulin G for Biosensor Applications

For many decades, feline infectious disease has been among the most common health problems and a leading cause of death in cats. These diseases include toxoplasmosis, feline leukemia virus (FeLV), and particularly feline immunodeficiency virus (FIV) disease. Early diagnosis is essential to increase the chance of successful treatment. Generally, measurement of the IgG level is considered to be indicative of an individual's immune status for a particular pathogen. The antibodies specific to feline IgG are crucial components for the development of a detection kit. In this study, feline IgG-bound scFv was selected using phage display technology. Three rounds of biopanning were conducted against purified feline IgG. Through an indirect enzyme-linked immunosorbent assay (ELISA), two scFv clones demonstrating the best binding ability to feline IgG were chosen for biochemical characterization. In addition, the selected scFv (N14) was expressed and purified in a bacterial system. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the size of the purified N14 was 29 kDa. A sandwich ELISA was used to evaluate the binding capacity of the purified scFv to feline IgG. As expected, the purified N14 had the capacity to bind feline IgG. Furthermore, N14 was modified to create a scFv-alkaline phosphatase (scFv-AP) fusion platform. The surface plasmon resonance (SPR) results revealed that N14-AP bound to feline IgG with an affinity binding value of 0.3 ± 0.496 μM. Additionally, the direct ELISA demonstrated the binding capacity of N14-AP to feline IgG in both cell lysate and purified protein. Moreover, N14-AP could be applied to detect feline IgG based on electrosensing with a detection limit of 10.42 nM. Overall, this study successfully selected a feline IgG-bound scFv and developed a scFv-AP platform that could be further engineered and applied in a feline infectious disease detection kit.

Diseases associated with feline leukemia virus and feline immunodeficiency virus infection: A retrospective study of 1470 necropsied cats (2010-2020)

Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are retroviruses affecting cats worldwide, and the prevalence of infection varies considerably according to the geographic area. We retrospectively described FIV- and FeLV-associated diseases in a population of 1470 necropsied cats, of which 396 (26.9%) were infected with FeLV, 199 (13.5%) with FIV, and 134 (9.1%) with FeLV and FIV concomitantly. Cats infected with FeLV (OR 3.4) and co-infected with FeLV and FIV (OR 1.9) were more likely to have neoplasms. The diagnosis of lymphoma and leukemia was higher in cats infected with FeLV (OR 3.9 and 19.4, respectively) and coinfected with FeLV and FIV (OR 1.9 and 19.3, respectively). The odds of diagnosing bacterial diseases were higher in cats coinfected with FeLV and FIV (OR: 2.8), whereas the odds of viral diseases were higher in those infected with FeLV (OR: 2.8), with 2.2 times more diagnoses of feline infectious peritonitis. Neoplastic and infectious diseases in FIV-infected cats did not differ significantly from those in uninfected cats. According to our results, a high prevalence of retroviral infections was observed in southern Brazil, mainly in relation to FeLV. Infected cats were significantly younger than uninfected cats. The main causes of death associated with FeLV infection and FeLV and FIV coinfection were neoplastic and infectious diseases. In contrast, FIV infection was not associated with any specific condition.

Field Performance of a Rapid Test to Detect Progressive, Regressive, and Abortive Feline Leukemia Virus Infections in Domestic Cats in Australia and Germany

Different feline leukemia virus (FeLV) infection outcomes are possible in cats following natural exposure, such as progressive infections (persistent viremia), regressive infections (transient or no viremia followed by proviral persistence) and abortive infections (presence of only antibodies). Laboratory-based testing is currently required for categorization of infection outcomes in cats. The aim of this study was to evaluate the field performance of a novel, rapid, combination point-of-care (PoC) test kit commercially available in Europe (v-RetroFel^®Ag/Ab; 2020-2021 version) to determine different FeLV infection outcomes by concurrent detection of FeLV antigen (p27) and antibodies against FeLV transmembrane envelope protein (p15E). A secondary aim was to evaluate the performance of the same test kit (v-RetroFel^®FIV) to determine positive/negative feline immunodeficiency virus (FIV) infection status by the detection of antibodies to FIV capsid protein (p24) and transmembrane glycoprotein (gp40). Two cohorts of domestic cats were recruited and tested with v-RetroFel^® using plasma or serum, including cats in Australia (n = 200) and cats in Germany (n = 170). Results from p27 antigen PoC testing, proviral DNA PCR, and neutralizing antibody testing or testing for antibodies against non-glycosylated surface unit envelope protein (p45) were used to assign cats to groups according to different FeLV infection outcomes. Testing with a laboratory-based FeLV p15E antibody ELISA was also performed for comparison. In the first cohort, v-RetroFel^®Ag/Ab correctly identified 89% (109/122) FeLV-unexposed cats and 91% (21/23) progressive infections, but no regressive (0/23) or abortive (0/32) infections. In the second cohort, v-RetroFel^®Ag/Ab correctly identified 94% (148/158) FeLV-unexposed cats and 100% (4/4) progressive infections, but no regressive (0/2) and only 17% (1/6) abortive infections. There was test agreement between v-RetroFel^®Ab and the p15E laboratory ELISA in 58.9% of samples. As a secondary outcome of this study, the sensitivity and specificity of v-RetroFel^®FIV testing in cohort 1 were 94.7% (18/19) and 98.3% (178/181), and in cohort 2, 30.0% (3/10) and 100.0% (160/160), respectively. Prior history of FIV vaccination did not produce any false-positive FIV results. In conclusion, v-RetroFel^®Ag/Ab (2020-2021 version) was unable to accurately determine different FeLV infection outcomes in the field. Improvements of the test prior to application to field samples are required.

Evaluation of a Point-of-Care Feline Immunodeficiency Virus (FIV) Test Kit (RapidSTATUS™ FIV) to Determine the FIV Status of FIV-Vaccinated and FIV-Unvaccinated Pet Cats in Australia

Simple Summary

This study evaluated a commercial point-of-care (PoC) feline immunodeficiency virus (FIV) test kit (RapidSTATUS™ FIV) for its accuracy in determining the FIV status of FIV-vaccinated and FIV-unvaccinated pet cats in Australia. In countries where FIV vaccination is used, veterinarians need a PoC kit that will produce a negative result for a FIV-uninfected cat, even if the cat is FIV-vaccinated or the FIV vaccination history is unknown, since incorrect diagnoses can impact negatively on the welfare of cats. FIV PoC kits also need to produce positive results in FIV-infected cats to help with appropriate management and to enable strategies to be implemented to prevent other cats from becoming FIV-infected. Results presented here show RapidSTATUS™ FIV to be highly accurate (98.8−100%) in a range of FIV-vaccinated and FIV-unvaccinated scenarios. Therefore, Australian veterinarians can reliably use RapidSTATUS™ FIV to rapidly and accurately determine the FIV status of all cats.

Abstract

Feline immunodeficiency virus (FIV) is a retrovirus that can cause immunosuppression, co-morbidities, and neoplasia in infected cats, and is commonly tested for in veterinary clinics and animal shelters in Australia. FIV diagnosis using point-of-care (PoC) kits to detect FIV antibodies in Australia is complicated by the commercial availability of an inactivated whole-FIV vaccine. The aim of this study was to determine the accuracy of the RapidSTATUS™ FIV antibody test kit in FIV-vaccinated and FIV-unvaccinated cats in Australia. Plasma from pet cats of known FIV vaccination and FIV infection statuses (n = 361), comprised of 57 FIV-uninfected cats annually vaccinated against FIV, 10 FIV-uninfected cats with lapsed FIV vaccination histories, 259 FIV-unvaccinated/FIV-uninfected cats, and 35 FIV-infected cats, was tested. RapidSTATUS™ FIV testing had sensitivity of 97.1% (34/35) and specificity of 100% (326/326), with an overall accuracy of 99.7% (360/361). Additional testing was undertaken using plasma from FIV-uninfected cats recently administered a primary FIV vaccination course (n = 12) or an annual booster FIV vaccination (n = 10). RapidSTATUS™ FIV was 98.8% (81/82) accurate and 100% (32/32) accurate in cats recently administered primary or annual FIV vaccinations, respectively. The high level of accuracy of RapidSTATUS™ FIV (98.8–100%) therefore establishes this PoC kit as a DIVA (differentiating infected from vaccinated animals) test. RapidSTATUS™ FIV is recommended to aid animal shelters, veterinarians, and researchers in Australia to accurately determine FIV infection status, irrespective of FIV vaccination history.

Clinicopathological and Epidemiological Findings in Pet Cats Naturally Infected with Feline Immunodeficiency Virus (FIV) in Australia

Feline immunodeficiency virus (FIV) infection in experimentally infected domestic cats produces characteristic clinical manifestations including hematological changes, neurological disease, neoplasia (most notably lymphoma) and lymphopenia-mediated immunodeficiency predisposing cats to a range of secondary infections. Conflicting reports exist, however, with regard to disease associations and survival time in naturally FIV-infected cats. The purpose of this retrospective case−control study was to investigate the effect of natural FIV infection on hematological, blood biochemical and urinalysis parameters and survival time in three cohorts of pet cats in Australia. Cohorts 1 and 2 were recruited from a large veterinary hospital in Melbourne, Victoria (n = 525 and 282), while a third cohort consisted of cats recruited from around Australia as part of a FIV field vaccine efficacy trial (n = 425). FIV-infected cats in cohorts 1, 2 and 3 were found to have 15/37 (41%), 13/39 (33%) and 2/13 (15%) clinicopathological parameters significantly different to FIV-uninfected cats, respectively. Two changes in FIV-infected cats in cohort 1, hypochromia (low hemoglobin) and hyperglobulinemia, were outside the supplied reference intervals and should serve as diagnostic triggers for FIV testing. Kaplan−Meier survival analysis of cats in cohorts 1 and 2 combined did not find any difference between FIV-infected and FIV-uninfected cats, however a confounding factor was a large euthanasia rate within the first 12 months in both groups. Three significant (p < 0.05) spatial clusters of FIV infection were identified in Melbourne. A possible relationship between FIV infection status and socioeconomic disadvantage was discovered, based on three government indices of socioeconomic status (p < 0.001). Until longitudinal field studies are performed in Australia to further investigate the long-term effects of natural FIV infection, Australian veterinarians should consider FIV to be an important infection of pet cats, and recommend measures to prevent FIV infection.

Risk factors and clinical and laboratory findings associated with feline immunodeficiency virus and feline leukemia virus infections in Bangkok, Thailand

Background and Aim: Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are retroviruses associated with chronic and neoplastic diseases in domestic and non-domestic cats. There has been increasing interest in the clinical importance of feline retroviruses in Thailand and the identification of associated risk factors in domestic cats. To prevent the spread of retroviral diseases and improve the management of retrovirus-infected cats, risk factors and associated clinical laboratory data must be clearly understood. This study aimed to identify the influence of household, lifestyle, health status, sterilization, clinical presentations, and laboratory findings on FIV- and FeLV-infected cats in Bangkok, Thailand. Materials and Methods: A total of 480 cats were evaluated for FeLV p27 antigen and FIV antibodies using Witness FeLV-FIV Rapid Test and SNAP FIV/FeLV Combo Test at a veterinary hospital service. Results: Of the 480 cats tested, 113 were positivefor virus infection, including 60 for FeLV (12.5%), 40 for FIV (8.3%), and 13 for both FeLV and FIV (2.7%). The findings revealed that the risk factors for cats infected with FeLV, FIV, or both FeLV and FIV were significantly different compared with those for non-infected cats (p < 0.05). Multivariate analysis showed that multi-cat ownership is a risk factor for the high prevalence of feline retrovirus infection, as multi-cat households exhibited a higher prevalence of infection than single-cat households. Anemic and sick cats were also at a greater risk of testing positive for specific retrovirus infections. FeLV-infected cats had a higher risk of anemia and low erythrocyte and thrombocyte counts (p ≤ 0.0001), whereas FIV-infected cats were more likely to have anemia and leukocytopenia than controls. Conclusion: Knowledge of the risk factors for retroviral diseases and associated clinical and laboratory findings can be used to develop strategies to reduce FIV and FeLV infections in cats.

Virus de la leucemia e inmunodeficiencia felina: un estudio retrospectivo en clínicas veterinarias particulares en Bogotá y Chía (Colombia), 2015-2019

Los virus de inmunodeficiencia y leucemia felina representan un problema de gran envergadura para los felinos domésticos debido a la multiplicidad de sintomatologías que manifiestan. El objetivo del presente estudio fue establecer, retrospectivamente, la prevalencia en la presentación de ViLeF y VIF en pacientes de seis clínicas de pequeños animales en Bogotá y Chía, en relación con factores como su edad, raza y género. Se realizó un estudio transversal y retrospectivo, mediante la recopilación de datos de 1.014 historias clínicas de pacientes felinos que ingresaron a seis clínicas de la ciudad de Bogotá y Chía, para determinar la prevalencia de VIF y ViLeF y la asociación de estas con factores como edad, género y raza, entre 2015 y 2019, a través de la prueba OR. La detección de los virus se realizó mediante una prueba rápida basada en inmunocromatografía. La mayor prevalencia para cada enfermedad por año fue: 12,3% para VIF en 2012 y 18% para ViLeF en 2019. Los machos presentaron mayores seroprevalencias para ambas enfermedades durante la mayoría los años evaluados. Factores como raza (criolla: VIF: 1,85; ViLeF: 2,01), género (macho: VIF: 1,53 OR; ViLeF: 1,64) y edad (> 7 años: VIF: 3,82; ViLeF: 3,21) se relacionaron positivamente con la presentación de ambas enfermedades en la población felina evaluada.

Feline immunodeficiency virus (FIV) infection in domestic pet cats in Australia and New Zealand: Guidelines for diagnosis, prevention and management

Despite the passage of over 30 years since its discovery, the importance of feline immunodeficiency virus (FIV) on the health and longevity of infected domestic cats is hotly debated amongst feline experts. Notwithstanding the absence of good quality information, Australian and New Zealand (NZ) veterinarians should aim to minimise the exposure of cats to FIV. The most reliable way to achieve this goal is to recommend that all pet cats are kept exclusively indoors, or with secure outdoor access (e.g., cat enclosures, secure gardens), with FIV testing of any in‐contact cats. All animal holding facilities should aim to individually house adult cats to limit the spread of FIV infection in groups of animals that are stressed and do not have established social hierarchies. Point‐of‐care (PoC) FIV antibody tests are available in Australia and NZ that can distinguish FIV‐infected and uninfected FIV‐vaccinated cats (Witness™ and Anigen Rapid™). Although testing of whole blood, serum or plasma remains the gold standard for FIV diagnosis, PoC testing using saliva may offer a welfare‐friendly alternative in the future. PCR testing to detect FIV infection is not recommended as a screening procedure since a negative PCR result does not rule out FIV infection and is only recommended in specific scenarios. Australia and NZ are two of three countries where a dual subtype FIV vaccine (Fel‐O‐Vax® FIV) is available and offers a further avenue for disease prevention. Since FIV vaccination only has a reported field effectiveness of 56% in Australia, and possibly lower in NZ, FIV‐vaccinated cats should undergo annual FIV testing prior to annual FIV re‐vaccination using a suitable PoC kit to check infection has not occurred in the preceding year. With FIV‐infected cats, clinicians should strive to be even more thorough than usual at detecting early signs of disease. The most effective way to enhance the quality of life and life expectancy of FIV‐infected cats is to optimise basic husbandry and to treat any concurrent conditions early in the disease course. Currently, no available drugs are registered for the treatment of FIV infection. Critically, the euthanasia of healthy FIV‐infected cats, and sick FIV‐infected cats without appropriate clinical investigations, should not occur.

The molecular and serological investigation of Feline immunodeficiency virus and Feline leukemia virus in stray cats of Western Turkey

This study aimed to investigate the Feline immunodeficiency virus (FIV) / Feline leukemia virus (FeLV) infection prevalence among looking healthy stray cats in Western Turkey by serologic and molecular-based tests. A total of 1008 blood samples from the stray cats were used in this study. All samples were tested for FIV antibodies / proviral DNA and FeLV antibodies / antigens / proviral DNA. The genetic characterization and phylogenetic analysis of FeLV and FIV were carried out in this study. These cats also tested for Leishmaniasis and Toxoplasmosis previously. FIV Ab and proviral DNA detected in 25.2 % and 25.5 % of samples, respectively. FeLV Ab, Ag, proviral DNA positivity was in 45.2 %, in 3.3 %, in 69.7 %, respectively. The molecular detection and phylogenetic analysis of the current FeLV pol gene and FIV gag gene performed. The molecular characterization for the pol gene of FeLV (enFeLV and exFeLV) among Turkey's cat population was reported for the first time. The exFeLV pol sequences closer to the FeLV-A genotype, and the enFeLV pol sequences overlapped with other enFeLV. The current FIV gag sequences were clustered within the subtypes A, B, and C. The findings revealed FeLV subtype A and FIV subtype-A, subtype-B, subtype-C circulate among Turkish stray cats. Single and multiple co-infection positivity was found higher compared to previous reports.

Antibody Responses in Cats Following Primary and Annual Vaccination against Feline Immunodeficiency Virus (FIV) with an Inactivated Whole-Virus Vaccine (Fel-O-Vax® FIV)

Although the antibody response induced by primary vaccination with Fel-O-Vax® FIV (three doses, 2-4 weeks apart) is well described, the antibody response induced by annual vaccination with Fel-O-Vax® FIV (single dose every 12 months after primary vaccination) and how it compares to the primary antibody response has not been studied. Residual blood samples from a primary FIV vaccination study (n = 11), and blood samples from cats given an annual FIV vaccination (n = 10), were utilized. Samples from all 21 cats were tested with a commercially available PCR assay (FIV RealPCRTM), an anti-p24 microsphere immunoassay (MIA), an anti-FIV transmembrane (TM; gp40) peptide ELISA, and a range of commercially available point-of-care (PoC) FIV antibody kits. PCR testing confirmed all 21 cats to be FIV-uninfected for the duration of this study. Results from MIA and ELISA testing showed that both vaccination regimes induced significant antibody responses against p24 and gp40, and both anti-p24 and anti-gp40 antibodies were variably present 12 months after FIV vaccination. The magnitude of the antibody response against both p24 and gp40 was significantly higher in the primary FIV vaccination group than in the annual FIV vaccination group. The differences in prime versus recall post-vaccinal antibody levels correlated with FIV PoC kit performance. Two FIV PoC kits that detect antibodies against gp40, namely Witness® and Anigen Rapid®, showed 100% specificity in cats recently administered an annual FIV vaccination, demonstrating that they can be used to accurately distinguish vaccination and infection in annually vaccinated cats. A third FIV PoC kit, SNAP® Combo, had 0% specificity in annually FIV-vaccinated cats, and should not be used in any cat with a possible history of FIV vaccination. This study outlines the antibody response to inactivated Fel-O-Vax® FIV whole-virus vaccine, and demonstrates how best to diagnose FIV infection in jurisdictions where FIV vaccination is practiced.

Anti-SU Antibody Responses in Client-Owned Cats Following Vaccination against Feline Leukaemia Virus with Two Inactivated Whole-Virus Vaccines (Fel-O-Vax® Lv-K and Fel-O-Vax® 5)

A field study undertaken in Australia compared the antibody responses induced in client-owned cats that had been vaccinated using two inactivated whole feline leukaemia virus (FeLV) vaccines, the monovalent vaccine Fel-O-Vax^® Lv-K and the polyvalent vaccine Fel-O-Vax^® 5. Serum samples from 428 FeLV-uninfected cats (118 FeLV-vaccinated and 310 FeLV-unvaccinated) were tested for anti-FeLV neutralising antibodies (NAb) using a live virus neutralisation assay to identify 378 FeLV-unexposed (NAb-negative) and 50 FeLV-exposed (NAb-positive; abortive infections) cats, following by anti-surface unit (SU) FeLV-A and FeLV-B antibody ELISA testing. An additional 42 FeLV-infected cats (28 presumptively regressively infected, 14 presumptively progressively infected) were also tested for anti-SU antibodies. NAb-positive cats displayed significantly higher anti-SU antibody ELISA responses compared to NAb-negative cats (p < 0.001). FeLV-unexposed cats (NAb-negative) that had been vaccinated less than 18 months after a previous FeLV vaccination using the monovalent vaccine (Fel-O-Vax^® Lv-K) displayed higher anti-SU antibody ELISA responses than a comparable group vaccinated with the polyvalent vaccine (Fel-O-Vax^® 5) (p < 0.001 for both anti-FeLV-A and FeLV-B SU antibody responses). This difference in anti-SU antibody responses between cats vaccinated with the monovalent or polyvalent vaccine, however, was not observed in cats that had been naturally exposed to FeLV (NAb-positive) (p = 0.33). It was postulated that vaccination with Fel-O-Vax^® 5 primed the humoral response prior to FeLV exposure, such that antibody production increased when the animal was challenged, while vaccination with Fel-O-Vax^® Lv-K induced an immediate preparatory antibody response that did not quantitatively increase after FeLV exposure. These results raise questions about the comparable vaccine efficacy of the different FeLV vaccine formulations and correlates of protection.

Prevalence of feline leukaemia virus and feline immunodeficiency virus in domestic cats in Ireland

Feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) are retroviruses affecting felid species worldwide. A study was performed over a period of 5 months in Ireland with the aim to get an updated and more realistic prevalence of these retroviruses. A total of 183 EDTA-anticoagulated whole-blood samples were collected from cats distributed between 10 clinics. The samples were tested using both point-of-care enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). Basic clinical data and vaccination history were also recorded for the sampled cats. The results of ELISA tests showed a prevalence of 10.4 and 3.3% for FIV and FeLV, respectively, and an apparent prevalence of 9.3% for FIV and 11.6% for FeLV with PCR. Phylogenetic analysis of the partial polymerase (pol) gene sequences obtained from 8 FIV-positive strains showed that all but one of the Irish strains belonged to FIV subtype A, and one to subtype B. The overall mean genetic similarity between the analysed strains was 91.15%.

Retrospective study of retroviruses by immunoenzymatic test on cats in Grande Vitória (ES, Brazil) and associated neoplasms

Retroviruses are among the leading causes of death in domestic cats. Retroviruses associate with the host cell in a persistent and permanent way, leading to diverse clinical conditions. The feline leukemia virus (FeLV) is the most pathogenic retrovirus with the potential to cause both degenerative diseases and immunosuppression, as well as proliferative diseases, as its association with the cell may lead to a direct oncogenic effect. The feline immunodeficiency virus (FIV), in turn, can lead to the classic immunodeficiency syndrome, usually has a chronic, less aggressive course and has no direct oncogenic effect. The use of vaccines and control measures has resulted in a decrease in the prevalence of FeLV in the United States of America (USA) and Europe, however, in Brazil, statistics show prevalence rates above 50%. This study aimed to assess the prevalence of feline retroviruses, by immunoenzymatic assay testing, in the region of Grande Vitória, in Espírito Santo and also point out the frequency of neoplasms in these cats. A total of 388 cats were retrospectively evaluated (2014-2016). The prevalence of FIV was 2.3% and FeLV was 33.7%. Neoplasms were identified in the three cats seropositive for FIV and FeLV and in three cats infected only with FIV. Neoplasms were also found in 26.6% of cats that were seropositive only for FeLV, especially mediastinal lymphoma. The high prevalence of FeLV demonstrated in this study highlights the need for establishing effective control measures, with emphasis on vaccination.

Post-release immune responses of Tasmanian devils vaccinated with an experimental devil facial tumour disease vaccine

Abstract ContextDisease is increasingly becoming a driver of wildlife population declines and an extinction risk. Vaccines are one of the most successful health interventions in human history, but few have been tested for mitigating wildlife disease. The transmissible cancer, devil facial tumour disease (DFTD), triggered the Tasmanian devil’s (Sarcophilus harrisii) inclusion on the international endangered species list. In 2016, 33 devils from a DFTD-free insurance population were given an experimental DFTD vaccination before their wild release on the Tasmanian northern coast. AimTo determine the efficacy of the vaccination protocol and the longevity of the induced responses. MethodSix trapping trips took place over the 2.5 years following release, and both vaccinated and incumbent devils had blood samples and tumour biopsies collected. Key resultsIn all, 8 of the 33 vaccinated devils were re-trapped, and six of those developed DFTD within the monitoring period. Despite the lack of protection provided by the vaccine, we observed signs of immune activation not usually found in unvaccinated devils. First, sera collected from the eight devils showed that anti-DFTD antibodies persisted for up to 2 years post-vaccination. Second, tumour-infiltrating lymphocytes were found in three of four biopsies collected from vaccinated devils, which contrasts with the ‘immune deserts’ typical of DFTs; only 1 of the 20 incumbent devils with DFTD had a tumour biopsy exhibiting immune-cell infiltrate. Third, immunohistochemical analysis of the vaccinated devils’ tumour biopsies identified the functional immune molecules associated with antigen-presenting cells (MHC-II) and T-cells (CD3), and the immune checkpoint molecule PD-1, all being associated with anti-tumour immunity in other species. ConclusionsThese results correlate with our previous study on captive devils in which a prophylactic vaccine primed the devil immune system and, following DFTD challenge and tumour growth, immunotherapy induced complete tumour regressions. The field trial results presented here provide further evidence that the devil immune system can be primed to recognise DFTD cells, but additional immune manipulation could be needed for complete protection or induction of tumour regressions. ImplicationsA protective DFTD vaccine would provide a valuable management approach for conservation of the Tasmanian devil.

Lack of protection against feline immunodeficiency virus infection among domestic cats in New Zealand vaccinated with the Fel-O-Vax® FIV vaccine

Infections with feline immunodeficiency virus (FIV) are common in New Zealand, although the impact of those infections on the health status of the cats remains unclear. Although many cats are vaccinated yearly with a commercial FIV vaccine containing FIV subtypes A and D, the effectiveness of this vaccine in protection against infection with field FIVs is unclear, as a high proportion of New Zealand viruses belong to subtype C. The objective of the study was to compare the frequency of FIV infection among adult FIV-vaccinated and FIV-unvaccinated domestic cats with access to outdoors. Buccal swabs were collected by the participating veterinarians and tested for the presence of FIV provirus by quantitative PCR. Overall, 26/185 (14.0 %) samples were positive for FIV, including 7/82 (8.5 %) samples from FIV-unvaccinated and 19/103 (18.4 %) from FIV-vaccinated cats. There was no protective effect of vaccination on FIV infection among sampled cats (p = 0.05). Partial sequences of the FIV envelope gene from five New Zealand viruses were analysed by the maximum likelihood method. All clustered with other New Zealand FIV sequences from subtypes A (n = 2), C (n = 2) or putative recombinant viruses (n = 1). While the FIV vaccination did not prevent FIV infection among sampled cats, it may have had an impact on transmissibility of the virus or on disease progression. As neither was addressed in the current study, further research is needed to fully assess the potential benefits of FIV vaccination. Considering the frequency of FIV infection in FIV-vaccinated cats, FIV infection status should be monitored not only before the first vaccination, but before each yearly booster.

2020 AAHA/AAFP Feline Vaccination Guidelines

The guidelines are a consensus report on current recommendations for vaccination of cats of any origin, authored by a Task Force of experts. The guidelines are published simultaneously in the Journal of Feline Medicine and Surgery (volume 22, issue 9, pages 813-830, DOI: 10.1177/1098612X20941784) and the Journal of the American Animal Hospital Association (volume 56, issue 4, pages 249-265, DOI: 10.5326/JAAHA-MS-7123). The guidelines assign approved feline vaccines to core (recommended for all cats) and non-core (recommended based on an individualized risk-benefit assessment) categories. Practitioners can develop individualized vaccination protocols consisting of core vaccines and non-core vaccines based on exposure and susceptibility risk as defined by the patient's life stage, lifestyle, and place of origin and by environmental and epidemiologic factors. An update on feline injection-site sarcomas indicates that occurrence of this sequela remains infrequent and idiosyncratic. Staff education initiatives should enable the veterinary practice team to be proficient in advising clients on proper vaccination practices and compliance. Vaccination is a component of a preventive healthcare plan. The vaccination visit should always include a thorough physical exam and client education dialog that gives the pet owner an understanding of how clinical staff assess disease risk and propose recommendations that help ensure an enduring owner-pet relationship.

2020 AAHA/AAFP Feline Vaccination Guidelines*

The guidelines are a consensus report on current recommendations for vaccination of cats of any origin, authored by a Task Force of experts. The guidelines are published simultaneously in the Journal of Feline Medicine and Surgery (volume 22, issue 9, pages 813–830, DOI: 10.1177/1098612X20941784) and the Journal of the American Animal Hospital Association (volume 56, issue 4, pages 249–265, DOI: 10.5326/JAAHA-MS-7123). The guidelines assign approved feline vaccines to core (recommended for all cats) and non-core (recommended based on an individualized risk-benefit assessment) categories. Practitioners can develop individualized vaccination protocols consisting of core vaccines and non-core vaccines based on exposure and susceptibility risk as defined by the patient’s life stage, lifestyle, and place of origin and by environmental and epidemiologic factors. An update on feline injection-site sarcomas indicates that occurrence of this sequela remains infrequent and idiosyncratic. Staff education initiatives should enable the veterinary practice team to be proficient in advising clients on proper vaccination practices and compliance. Vaccination is a component of a preventive healthcare plan. The vaccination visit should always include a thorough physical exam and client education dialog that gives the pet owner an understanding of how clinical staff assess disease risk and propose recommendations that help ensure an enduring owner-pet relationship.

2020 AAFP Feline Retrovirus Testing and Management Guidelines

CLINICAL IMPORTANCE

Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) infections are found in cats worldwide. Both infections are associated with a variety of clinical signs and can impact quality of life and longevity.

SCOPE

This document is an update of the 2008 American Association of Feline Practitioners' feline retrovirus management guidelines and represents current knowledge on pathogenesis, diagnosis, prevention and treatment of retrovirus infections in cats.

TESTING AND INTERPRETATION

Although vaccines are available for FeLV in many countries and for FIV in some countries, identification of infected cats remains an important factor for preventing new infections. The retrovirus status of every cat at risk of infection should be known. Cats should be tested as soon as possible after they are acquired, following exposure to an infected cat or a cat of unknown infection status, prior to vaccination against FeLV or FIV, and whenever clinical illness occurs. It might not be possible to determine a cat's infection status based on testing at a single point in time; repeat testing using different methods could be required. Although FeLV and FIV infections can be associated with clinical disease, some infected cats, especially those infected with FIV, can live for many years with good quality of life.

MANAGEMENT OF INFECTED CATS

There is a paucity of data evaluating treatments for infected cats, especially antiretroviral and immunomodulatory drugs. Management of infected cats is focused on effective preventive healthcare strategies, and prompt identification and treatment of illness, as well as limiting the spread of infection.

Risk of Feline Immunodeficiency Virus (FIV) Infection in Pet Cats in Australia is Higher in Areas of Lower Socioeconomic Status

Simple Summary

Some diseases are known to occur at a higher frequency in Australia in areas of social and economic disadvantage. Identification of these diseases is important for effective infection control strategies. We investigated whether an association existed between socioeconomic factors and three infectious diseases in cats (feline immunodeficiency virus, FIV; feline calicivirus, FCV; and feline herpesvirus-1, FHV-1) in Australia. Disease cases that were reported to a voluntary veterinary disease surveillance system (Disease WatchDog) between January 2010 and July 2017 were extracted and analysed. Postcodes of the owners of these cats were compared to four government-published indexes measuring socioeconomic disadvantage and advantage. An association between socioeconomic status and FIV infection, but not FCV and FHV-1 infection, was found. FIV infection was more commonly reported in areas of socioeconomic disadvantage according to all four indexes. Prevention strategies targeting lower socioeconomic communities may help to reduce the overall prevalence of FIV infection in Australia.

Abstract

Feline immunodeficiency virus (FIV), feline calicivirus (FCV), and feline herpesvirus (FHV-1) are common viral infections of domestic cats in Australia. A study was performed to investigate the possible effect of area-based socioeconomic factors on the occurrence of FIV, FCV, and FHV-1 infection in Australian client-owned cats. A total of 1044 cases, reported to a voluntary Australian online disease surveillance system between January 2010 and July 2017, were analysed with respect to their postcode-related socioeconomic factors using the Socio-Economic Indexes For Areas (SEIFA). SEIFA consists of four different indexes which describe different aspects of socioeconomic advantage and disadvantage. Signalment details including age, sex, neuter status, and breed were also considered. A significant correlation was observed between areas of lower socioeconomic status and a higher number of reported cases of FIV infection for all four SEIFA indexes (p ≤ 0.0002). Postcodes with SEIFA indexes below the Australian median (“disadvantaged” areas) were 1.6–2.3 times more likely to have reported cases of FIV infection than postcodes with SEIFA indexes above the median (“advantaged” areas). In contrast, no correlation was observed between the number of reported cases of FCV or FHV-1 infection and any of the four SEIFA indexes (p > 0.05). When signalment data were analysed for the three infections, FIV-infected cats were more likely to be older (p < 0.00001), male (p < 0.0001), neutered (p = 0.03), and non-pedigree (p < 0.0001) compared to FCV and FHV-1 infected cats. Results from this study suggest that area-based disease control strategies, particularly in areas of social disadvantage, might be effective in reducing the prevalence of FIV infection in pet cats in Australia.

Decreased Sensitivity of the Serological Detection of Feline Immunodeficiency Virus Infection Potentially Due to Imported Genetic Variants

Feline immunodeficiency virus (FIV) is a lentivirus of domestic cats worldwide. Diagnosis usually relies on antibody screening by point-of-care tests (POCT), e.g., by enzyme-linked immunosorbent assays (ELISA), and confirmation using Western blot (WB). We increasingly observed ELISA-negative, WB-positive samples and aimed to substantiate these observations using 1194 serum/plasma samples collected from 1998 to 2019 primarily from FIV-suspect cats. While 441 samples tested positive and 375 tested negative by ELISA and WB, 81 samples had discordant results: 70 were false ELISA-negative (WB-positive) and 11 were false ELISA-positive (WB-negative); 297 ambiguous results were not analyzed further. The diagnostic sensitivity and specificity of the ELISA (82% and 91%, respectively) were lower than those reported in 1995 (98% and 97%, respectively). The diagnostic efficiency was reduced from 97% to 86%. False ELISA-negative samples originated mainly (54%) from Switzerland (1995: 0%). Sixty-four false ELISA-negative samples were available for POCT (SNAP^TM/WITNESS^R): five were POCT-positive. FIV RT-PCR was positive for two of these samples and was weakly positive for two ELISA- and POCT-negative samples. Low viral loads prohibited sequencing. Our results suggest that FIV diagnosis has become more challenging, probably due to increasing travel by cats and the introduction of new FIV isolates not recognized by screening assays.

The Diagnosis of Feline Leukaemia Virus (FeLV) Infection in Owned and Group-Housed Rescue Cats in Australia

A field study was undertaken to (i) measure the prevalence of feline leukaemia virus (FeLV) exposure and FeLV infection in a cross-section of healthy Australian pet cats; and (ii) investigate the outcomes following natural FeLV exposure in two Australian rescue facilities. Group 1 (n = 440) consisted of healthy client-owned cats with outdoor access, predominantly from eastern Australia. Groups 2 (n = 38) and 3 (n = 51) consisted of a mixture of healthy and sick cats, group-housed in two separate rescue facilities in Sydney, Australia, tested following identification of index cases of FeLV infection in cats sourced from these facilities. Diagnostic testing for FeLV exposure/infection included p27 antigen testing using three different point-of-care FeLV kits and a laboratory-based ELISA, real-time polymerase chain reaction (qPCR) testing to detect FeLV proviral DNA in leukocytes, real-time reverse-transcription PCR (qRT-PCR) testing to detect FeLV RNA in plasma, and neutralising antibody (NAb) testing. Cats were classified as FeLV-uninfected (FeLV-unexposed and presumptively FeLV-abortive infections) or FeLV-infected (presumptively regressive and presumptively progressive infections). In Group 1, 370 FeLV-unexposed cats (370/440, 84%), 47 abortive infections (47/440, 11%), nine regressive infections (9/440, 2%), and two progressive infections (2/440, 0.5%) were identified, and 12 FeLV-uninfected cats (12/440, 3%) were unclassifiable as FeLV-unexposed or abortive infections due to insufficient samples available for NAb testing. In Groups 2 and 3, 31 FeLV-unexposed cats (31/89, 35%), eight abortive infections (8/89, 9%), 22 regressive infections (22/89; 25%), and 19 progressive infections (19/89; 21%) were discovered, and nine FeLV-uninfected cats (9/89; 10%) were unclassifiable due to insufficient samples available for NAb testing. One of the presumptively progressively-infected cats in Group 3 was likely a focal FeLV infection. Two other presumptively progressively-infected cats in Group 3 may have been classified as regressive infections with repeated testing, highlighting the difficulties associated with FeLV diagnosis when sampling cats at a single time point, even with results from a panel of FeLV tests. These results serve as a reminder to Australian veterinarians that the threat of FeLV to the general pet cat population remains high, thus vigilant FeLV testing, separate housing for FeLV-infected cats, and FeLV vaccination of at-risk cats is important, particularly in group-housed cats in shelters and rescue facilities, where outbreaks of FeLV infection can occur.

Avaliação de dois testes sorológicos comerciais para diagnóstico das infecções pelo FIV e pelo FeLV

RESUMO FIV e FeLV são retrovírus associados principalmente com neoplasias. Dois testes rápidos são disponibilizados no Brasil para o diagnóstico dessas infecções: um kit de imunocromatografia de fluxo bidirecional (SNAP® Combo IDEXX) e um kit de imunocromatografia de fluxo lateral unidirecional (ALERE/BIONOTE Anigen Rapid). O objetivo deste estudo foi comparar o teste SNAP® com o teste ALERE. Amostras de sangue de 178 gatos foram testadas utilizando-se ambos os kits. A reação em cadeia de polimerase em tempo real (qPCR) foi empregada como método confirmatório para todos os resultados. O teste SNAP® apresentou sensibilidade e especificidade de 100% para FIV; a sensibilidade e a especificidade do teste ALERE foram de 96,15% e 98,68%, respectivamente. A sensibilidade e a especificidade para o FeLV foram de 93,02% e 96,30% para o teste SNAP® e de 90,70% e 97,78% para o teste ALERE. Ainda em relação ao FeLV, três amostras com resultado positivo na qPCR obtiveram resultado falso-negativo em ambos os testes. Não houve diferença estatisticamente significante entre os métodos. Considerando a qPCR como padrão-ouro, o teste SNAP® apresentou maior sensibilidade e especificidade para o FIV, e o teste ALERE apresentou maior especificidade para o FeLV. Os resultados mostraram uma boa correlação entre os testes.

Changes Associated with Improved Outcomes for Cats Entering RSPCA Queensland Shelters from 2011 to 2016

Simple Summary

The aim of this study was to identify changes that contributed to the markedly improved live release of cats in Royal Society for the Prevention of Cruelty to Animals (RSPCA) Queensland shelters by comparing data from 2011 and 2016. Admission numbers were similar in these two years. The number and percentage euthanized decreased substantially from 58% in 2011 to 15% in 2016. The greatest contributor to this were marked increases in cats rehomed (i.e., adopted). The number of cats adopted doubled from 2011 to 2016, with over half the increase contributed by increased shelter adoptions, and the remainder achieved by increased off-site adoptions, largely through agreements with Petbarn stores. Improved outcomes were facilitated by nearly doubling the number of cats temporarily in foster care. Cats euthanized for behavioral reasons decreased by 85%, including a marked decrease in the number of euthanasias because the cat was deemed feral. Euthanasia of young kittens dramatically decreased. The number of cats reclaimed by their owner was similar in the two years and was only a small contributor to the numbers of cats released live. To achieve further improvements, programs that decrease intake for both stray and owned cats would be beneficial.

Abstract

This retrospective study of cat admissions to RSPCA Queensland shelters describes changes associated with improved outcomes ending in live release in 2016 compared to 2011. There were 13,911 cat admissions in 2011 and 13,220 in 2016, with approximately 50% in both years admitted as strays from the general public or council contracts. In contrast, owner surrenders halved from 30% to 15% of admissions. Percentages of admissions ending in euthanasia decreased from 58% to 15%. Only 5% of cat admissions were reclaimed in each of these years, but the percentage rehomed increased from 34% to 74%, of which 61% of the increase was contributed by in-shelter adoptions and 39% from non-shelter sites, predominately retail partnerships. The percentage temporarily fostered until rehoming doubled. In 2011, euthanasias were most common for medical (32% of all euthanasias), behavioral (36%) and age/shelter number (30%) reasons, whereas in 2016, 69% of euthanasias were for medical reasons. The number of young kittens euthanized decreased from 1116 in 2011 to 22 in 2016. The number of cats classified as feral and euthanized decreased from 1178 to 132, in association with increased time for assessment of behavior and increased use of behavior modification programs and foster care. We attribute the improved cat outcomes to strategies that increased adoptions and reduced euthanasia of young kittens and poorly socialized cats, including foster programs. To achieve further decreases in euthanasia, strategies to decrease intake would be highly beneficial, such as those targeted to reduce stray cat admissions.

Prevalence and risk factor analysis for feline haemoplasmas in cats from Northern Serbia, with molecular subtyping of feline immunodeficiency virus

Objectives

The objectives of this study were to estimate the prevalence of feline haemoplasma infections in Northern Serbia, identify potential risk factors and perform molecular subtyping of feline immunodeficiency virus (FIV).

Methods

PCR analysis for feline haemoplasmas was performed on surplus EDTA blood samples from 373 cats from the Belgrade region, Serbia. An ELISA was used to determine the prevalence of feline leukaemia virus (FeLV) and FIV; PCR was performed on a subpopulation of these cats. FIV subtyping was performed using PCR.

Results

Within this population, 64/373 cats (17.2%) were infected with one or more haemoplasma species. Mycoplasma haemofelis was detected in 20/373 cats (5.4%), ‘Candidatus Mycoplasma haemominutum’ in 47/373 cats (12.6%) and ‘Candidatus Mycoplasma turicensis’ in 23/373 cats (6.2%). Coinfections were observed in 21/373 cats (5.6%). Based on ELISA serological retroviral testing, 4/310 cats (1.3%) were infected with FeLV, whereas 78/331 (23.6%) were infected with FIV. Multivariable analysis identified significant associations between haemoplasma infection and anaemia (anaemic/non-anaemic, odds ratio [OR] 2.7, 95% confidence interval [CI] 1.04–7.1; P = 0.041]), male gender (male/female, OR 4.5, 95% CI 2.22–9.03; P <0.0005), outdoor access (yes/no, OR 5.2, 95% CI 2.28–11.92; P <0.0005), non-pedigree breed (non-pedigree/pedigree, OR 5.5, 95% CI 1.24–24.84; P = 0.025) and FIV seropositive status (positive/negative, OR 2.4, 95% CI 1.21–4.83; P = 0.012). PCR analysis of the FIV ELISA-positive samples revealed clade D as being the most prevalent.

Conclusions and relevance

All three known species of feline haemoplasma were detected, confirming their presence in Serbia; ‘Candidatus Mycoplasma haemominutum’ was the most prevalent. We found a high prevalence of FIV-infected cats and FIV clade D was most prevalent.

Prevalence of feline immunodeficiency virus and feline leukaemia virus infection in Malaysia: a retrospective study

Objectives

Feline ownership is popular and represents the largest segment of the pet population in Malaysia. Most feline owners own, on average, 2–3 cats, with some having >10 cats per household. Feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) are two clinically important viral infections in cats. Documenting the prevalence of these diseases in the feline population is important for both veterinarians and the public.

Methods

This was a retrospective study, using data collected from the domestic cat population seen at a 24 h private veterinary hospital in Malaysia, to determine the prevalence of FIV and FeLV in an urban area and risk factors associated with these infections. Between 2010 and 2016, 2230 blood samples were collected and tested for FIV antibodies and FeLV antigen using commercially available ELISA test kits.

Results

In total, 10.0% (n = 224; 95% confidence interval [CI] 8.80–11.26) were seropositive for FIV; 12.0% (n = 267; 95% CI 10.62–13.32) were seropositive for FeLV; and 2.6% (n = 58; 95% CI 2.01–3.17) were seropositive for both.

Conclusions and relevance

The prevalence of FIV is lower and FeLV higher than previously documented for this region. Because of the immunosuppressive potential of both viruses, client education and use of appropriate control strategies such as routine screening, vaccination and eradication should be considered.

Duration of antibody response following vaccination against feline immunodeficiency virus

Objectives Recently, two point-of-care (PoC) feline immunodeficiency virus (FIV) antibody test kits (Witness and Anigen Rapid) were reported as being able to differentiate FIV-vaccinated from FIV-infected cats at a single time point, irrespective of the gap between testing and last vaccination (0-7 years). The aim of the current study was to investigate systematically anti-FIV antibody production over time in response to the recommended primary FIV vaccination series. Methods First, residual plasma from the original study was tested using a laboratory-based ELISA to determine whether negative results with PoC testing were due to reduced as opposed to absent antibodies to gp40. Second, a prospective study was performed using immunologically naive client-owned kittens and cats given a primary FIV vaccination series using a commercially available inactivated whole cell/inactivated whole virus vaccine (Fel-O-Vax FIV, three subcutaneous injections at 4 week intervals) and tested systematically (up to 11 times) over 6 months, using four commercially available PoC FIV antibody kits (SNAP FIV/FeLV Combo [detects antibodies to p15/p24], Witness FeLV/FIV [gp40], Anigen Rapid FIV/FeLV [p24/gp40] and VetScan FeLV/FIV Rapid [p24]). Results The laboratory-based ELISA showed cats from the original study vaccinated within the previous 0-15 months had detectable levels of antibodies to gp40, despite testing negative with two kits that use gp40 as a capture antigen (Witness and Anigen Rapid kits). The prospective study showed that antibody testing with SNAP Combo and VetScan Rapid was positive in all cats 2 weeks after the second primary FIV vaccination, and remained positive for the duration of the study (12/12 and 10/12 cats positive, respectively). Antibody testing with Witness and Anigen Rapid was also positive in a high proportion of cats 2 weeks after the second primary FIV vaccination (8/12 and 7/12, respectively), but antibody levels declined below the level of detection in most cats (10/12) by 1 month after the third (final) primary FIV vaccination. All cats tested negative using Witness and Anigen Rapid 6 months after the third primary FIV vaccination. Conclusions and relevance This study has shown that a primary course of FIV vaccination does not interfere with FIV antibody testing in cats using Witness and Anigen Rapid, provided primary vaccination has not occurred within the previous 6 months. Consequently, Witness and Anigen Rapid antibody test kits can be used reliably to determine FIV infection status at the time of annual booster FIV vaccination to help detect 'vaccine breakthroughs' and in cats that have not received a primary course of FIV vaccination within the preceding 6 months. The duration of antibody response following annual booster FIV vaccination and the resulting effect on antibody testing using PoC kits needs to be determined by further research. The mechanism(s) for the variation in FIV antibody test kit performance remains unclear.

Epidemiology and clinical outcomes of feline immunodeficiency virus and feline leukaemia virus in client-owned cats in New Zealand

Objectives

The objectives were to collect baseline data on the occurrence, testing and vaccination practices, and clinical outcomes of feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV) in New Zealand

Methods

A cross-sectional survey of 423 veterinary practices in New Zealand was performed to collect data on FeLV and FIV testing and vaccination during the 2015 calendar year. Clinical records from 572 cats tested using a point-of-care ELISA at a first-opinion veterinary practice between 7 April 2010 and 23 June 2016 were also obtained and multivariable logistic regression models were constructed to identify risk factors for test positivity. Survival times were estimated using Kaplan–Meier methods.

Results

The survey was completed by 112 clinics (26.4%) of which 72 performed in-house testing. Of the 2125 tests performed, 56 (2.6%) were positive for FeLV and 393 (18.5%) were positive for FIV. Fewer than 1% of cats were vaccinated for FeLV, with veterinarians citing low perceived prevalence as the primary reason for not vaccinating. Being male compared with being female and having clinical evidence of immunosuppression were significant risk factors for both FeLV and FIV test positivity. The median survival times of FeLV and FIV test-positive cats were 10 days (95% confidence interval [CI] 0–16) and 650 days (95% CI 431–993), respectively.

Conclusions and relevance

Testing and vaccination for FeLV and FIV in New Zealand appears targeted towards high-risk animals, which may bias prevalence estimates. Baseline data should be monitored for changes in FeLV epidemiology now commercial vaccines are no longer available.

Prevalence and risk factors for cats testing positive for feline immunodeficiency virus and feline leukaemia virus infection in cats entering an animal shelter in New Zealand

AIMS To estimate the prevalence of cats testing positive for antibodies to feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) antigens in domestic cats entering a New Zealand animal shelter, based on a commercial point-of-care ELISA, to identify risk factors associated with cats testing positive, and to compare the results obtained from the ELISA with those obtained using PCR-based testing. METHOD A cross-sectional study was performed on 388 cats entering the Royal New Zealand Society for the Prevention of Cruelty to Animals animal shelter in Auckland, New Zealand between 7 February 2014 and 30 May 2014. Whole blood samples were collected from each cat and tested for FIV antibody and FeLV antigen using a commercial point-of-care ELISA. Information on the signalment and health status of the cat at the time of entry was also recorded. Blood and saliva samples from a subset of cats were tested for FIV and FeLV proviral DNA using a real-time PCR assay. RESULTS Of the 388 cats in the study sample, 146 (37.6%) had been relinquished by owners, 237 (62.4%) were strays, and 5 (1.3%) were of unknown origin. Overall, 53/388 (13.7%) cats tested positive for FIV antibodies and 4/388 (1.0%) were positive for FeLV antigen. Stray cats had a higher FIV seroprevalence than relinquished cats (42/237 (17.8%) vs. 11/146 (7.5%); p=0.008). Of 53 cats that were FIV-seropositive, 51 (96%) tested positive for FIV proviral DNA using PCR testing of blood. Of these 51 cats, 28 (55%) were positive by PCR testing of saliva. Of the four cats that were FeLV antigen-positive by ELISA, two (50%) were positive for FeLV proviral DNA by PCR testing of blood. The odds of a cat being seropositive for FIV were greater for intact compared to desexed cats (OR=3.3; 95% CI=1.6-7.4) and for male compared to female cats (OR=6.5; 95% CI=3.2-14.0). CONCLUSIONS AND CLINICAL RELEVANCE The seroprevalence for FIV was 14% among cats entering an animal shelter in Auckland, whereas the prevalence of FeLV antigen-positive cats was only 1%. These findings suggest differences in the transmission dynamics of each virus in free-roaming cat populations in New Zealand. Our study also highlights the potential role of desexing cats in reducing transmission of FIV. However, further data from first-opinion veterinary practices are required to confirm that these findings may be generalised to the wider domestic cat population in New Zealand.

Performance of 4 Point-of-Care Screening Tests for Feline Leukemia Virus and Feline Immunodeficiency Virus

Background

More than 3 million cats in the United States are infected with FeLV or FIV. The cornerstone of control is identification and segregation of infected cats.

Hypothesis/Objectives

To compare test performance with well‐characterized clinical samples of currently available FeLV antigen/FIV antibody combination test kits.

Animals

Surplus serum and plasma from diagnostic samples submitted by animal shelters, diagnostic laboratories, veterinary clinics, and cat research colonies. None of the cats had been vaccinated against FIV. The final sample set included 146 FeLV+, 154 FeLV−, 94 FIV+, and 97 FIV− samples.

Methods

Prospective, blind comparison to a gold standard: Samples were evaluated in 4 different point‐of‐care tests by ELISA antigen plate tests (FeLV) and virus isolation (FIV) as the reference standards. All test results were visually read by 2 blinded observers.

Results

Sensitivity and specificity, respectively, for FeLV were SNAP^® (100%/100%), WITNESS^® (89.0%/95.5%), Anigen^® (91.8%/95.5%), and VetScan^® (85.6%/85.7%). Sensitivity and specificity for FIV were SNAP^® (97.9%/99.0%), WITNESS^® (94.7%/100%), Anigen^® (96.8%/99.0%), and VetScan^® (91.5%/99.0%).

Conclusions and Clinical Importance

The SNAP^® test had the best performance for FeLV, but there were no significant differences for FIV. In typical cat populations with seroprevalence of 1–5%, a majority of positive results reported by most point‐of‐care test devices would be false‐positives. This could result in unnecessary segregation or even euthanasia.

Seroprevalence of feline immunodeficiency virus and feline leukaemia virus in Australia: risk factors for infection and geographical influences (2011-2013)

OBJECTIVES

Our aim was to: (i) determine the current seroprevalence of feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) in three large cohorts of cats from Australia; and (ii) investigate potential risk factors for retroviral infection.

METHODS

Cohort 1 (n = 2151 for FIV, n = 2241 for FeLV) consisted of cats surrendered to a shelter on the west coast of Australia (Perth, Western Australia [WA]). Cohort 2 (n = 2083 for FIV, n = 2032 for FeLV) consisted of client-owned cats with outdoor access recruited from around Australia through participating veterinary clinics. Cohort 3 (n = 169 for FIV, n = 166 for FeLV) consisted of cats presenting to Murdoch University Veterinary Hospital for a variety of reasons. Fresh whole blood was collected and tested using a commercially available point-of-care lateral flow ELISA kit that detects p27 FeLV antigen and antibodies to FIV antigens (p15 and p24) (cohorts 1 and 2), or one of two lateral flow immunochromatography kits that detect p27 antigen and antibodies to FIV antigen (p24 and/or gp40) (cohort 3). Data recorded for cats in cohort 2 included signalment, presenting complaint and postcode, allowing investigation of risk factors for FIV or FeLV infection, as well as potential geographical 'hot spots' for infection.

RESULTS

The seroprevalence of FIV was 6% (cohort 1), 15% (cohort 2) and 14% (cohort 3), while the seroprevalence of FeLV was 1%, 2% and 4% in the same respective cohorts. Risk factors for FIV infection among cats in cohort 2 included age (>3 years), sex (male), neutering status (entire males) and location (WA had a significantly higher FIV seroprevalence compared with the Australian Capital Territory, New South Wales and Victoria). Risk factors for FeLV infection among cats in cohort 2 included health status ('sick') and location (WA cats were approximately three times more likely to be FeLV-infected compared with the rest of Australia). No geographical hot spots of FIV infection were identified.

CONCLUSIONS AND RELEVANCE

Both FIV and FeLV remain important infections among Australian cats. WA has a higher seroprevalence of both feline retroviruses compared with the rest of Australia, which has been noted in previous studies. A lower neutering rate for client-owned male cats is likely responsible for the higher seroprevalence of FIV infection in WA cats, while the reason for the higher seroprevalence of FeLV in WA cats is currently unknown.