Feline Immunodeficiency Virus: characteristics and role in pathology

The review describes structure and biology feline immunodeficiency virus, epidemiology, clinical manifistation, immunological and immunogenetic characteristics of the pathogenesis, principles of diagnosis, treatment and prophylactic. This is a brief overview of the current state of knowledge of this virus. The feline immunodefficiency virus (FIV) is a retrovirus of the Lentivirus genus (Family Retroviridae) was initially isolated from colony of domestic cats in California (USA) in 1986 and has now been recognized as a common feline pathogen worldwide. FIV closely related to HIV, which infect members of Felidae family and it is an importmant viral pathogen worldwide in the domestic cats. FIV these reasons has been studied widely as both an important veterinary pathogen and an animal model for HIV/AIDS. However, it is important to emphasise that humans are not susceptible to FIV infection. The main cellular target for FIV is the CD4+ T cell. FIV causes an immune system disease in domestic cats involving depletion of the CD4+ population of T lymphocytes, increased susceptibility to opportunistic infections, and sometimes death. Seven genetically distinct subtypes has been defined (A,B,C,D,E,F,U-Nzenv).The seroprevalence of feline immunodeficiency virus infection of cats varies markedly between geographic regions. Transmission of FIV is principally by parenteral inoculation of the virus in blood and saliva, presuamably via biting during fighting. Most clinical signs are not directly caused by FIV, clinical signs will be the result of a secondary infection. The virus itself is responsible for immunodeficiency or immune stimulation. Chronic gingivostomatitis one of the most common presenting signs in FIV-infected cats. Methods of diagnosis are included virus isolation (not used routinely), polymerase chain reaction with sensitive and specificities ranging from 40-100%. These techniques result in relatively high numbers of false-positive and false-negative results. Routinely, FIV-infection is diagnosed by detecting antibodies using ELISA and immunochro-matography methods. Western blot analysis is considered the "gold standart" for FIV serology to confirm questionable results. The most common drugs used for treatment of FIV-infection: reverse transcriptase inhibitors drugs, that ingibit firal ensymes, such as DNA or RNA polymerases, integrase ingibitors, protease ingibitors; and interferons. Development of an effective vaccine against FIV is difficult because of the high number and variations of the virus strains. Vaccines that only protect against a single virus variant, have already demonstrated a good efficacy against homologous FIV strains. This review summaries pertinent findings about FIV from work published in a variety research journals.

Comparison of subclinical dermatophyte infection in short- and long-haired cats

Background and Aim: Long-haired cats may have an increased risk of dermatophytosis due to insufficient grooming and their thick hair coat trapping fungal spores. The prevalence of subclinical dermatophytosis in long-haired cats was evaluated using fungal culture and Wood's lamp test. Hematology and blood chemistry results were compared between cats negative and positive for dermatophytosis. Materials and Methods: A total of 127 cats (median age, 3 years [range, 10 months-10 years]) without feline leukemia virus or feline immunodeficiency virus infection were classified into short-haired (n=64) and long-haired (n=63) groups. Hair samples were cultured on a fungal culture medium (dermatophyte test medium, enhanced sporulation agar, and Sabouraud agar). Results: The prevalence of dermatophytosis in short-haired and long-haired cats was 6.25% (95% confidence interval [CI], 2.15-12.28) and 34.92% (95% CI, 22.94-46.90), respectively. The odds of long-haired cats having dermatophytosis were 8.05 (95% CI, 2.44-33.97) times greater than that in short-haired cats. The number of positive dermatophytosis found in domestic short-haired cats (2/50, 4.0%) was significantly lower than that in Persian cats (17/47, 36.17%; p<0.001) and long-haired mixed breed cats (3/7, 42.86%; p=0.011). The overall sensitivity and specificity of the Wood's lamp test for diagnosing Microsporum canis infection were 37.5% (95% CI, 21.2-57.3%) and 96.1% (95% CI, 90.4-98.5%), respectively. Cats with dermatophytosis had significantly lower hematocrit and serum albumin levels than cats without dermatophytosis. Conclusion: Subclinical dermatophytosis was more common in long-haired cats; therefore, dermatophyte examinations should be performed routinely.

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 (SNAPTM/WITNESSR): 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.