Feline leukemia virus and feline immunodeficiency virus.

Ophthalmic manifestations of FeLV or FIV infection can occur in all ocular tissues and may be manifestations of direct viral effects or secondary to viral-related malignant transformation. Additionally, the manifestations of common feline ophthalmic pathogens may be more severe and poorly responsive to therapy because of the immunosuppressive effects of FeLV or FIV infection. Prompt diagnosis of underlying viral infection in cats with ophthalmic disease is paramount for accurate diagnosis and prognosis and is required for appropriate therapeutic decision making.     

Feline immunodeficiency virus: a brief review.

Feline immunodeficiency virus (FIV), previously known as feline T-lymphotropic lentivirus (FTLV), was first described by Pedersen et al. (1987) who isolated the virus from cats with a variety of clinical signs suggestive of immunodeficiency. Since then FIV has become one of the most studied feline viruses, not least because of its similarity to human immunodeficiency viruses (HIV) which cause acquired immunodeficiency syndrome (AIDS) in man.     

Feline immunodeficiency virus: prevalence, disease associations and isolation

Of 467 cat serums tested for antibody to feline immunodeficiency virus (FIV) 120 (26%) were positive. The average age of positive cats was 7.5 years (range 1 to 16 years), and 67% were male. Of 110 serums collected in 1980, 27 (24.5%) were positive. A wide variety of clinical signs including oral cavity disease, anorexia, weight loss, lethargy, depression, fever, respiratory and urinary tract disease, conjunctivitis, abscesses, anaemia and lymphadenopathy were observed in the cats with serum antibody. There was often a history of chronic disease or recurrence of particular or various clinical signs in these cats. FIV was isolated from 4 of 8 FIV antibody positive cats by cocultivation of patient lymphocytes with donor lymphocytes in the presence of interleukin 2.     

Feline leukemia virus and feline immunodeficiency virus in Canada: recommendations for testing and management

Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are common and important infectious disease agents of cats in Canada. Seroprevalence data for FeLV and FIV in various populations of Canadian cats are reviewed and recommendations for testing and management of infections by these viruses in cats in Canada are presented. Retrovirus testing in Canada is infrequent in comparison with the United States, and efforts should be focused on reducing physical and other barriers to testing, and on education of veterinarians, veterinary team members, and cat owners regarding the importance of testing. New test methodologies for FeLV and FIV are emerging, and should be independently evaluated in order to provide practitioners with information on test reliability. Finally, more information is needed on FIV subtypes in Canada to improve diagnostics and vaccines, and to provide information on disease outcomes.     

Feline insular amyloid: immunohistochemical and immunochemical evidence that the amyloid is insulin-related

Utilizing islet amyloid-laden pancreatic tissues from six diabetic cats, we demonstrated substantial immunoreactivity (peroxidase-antiperoxidase technique) of the islet amyloid with antiserum to a B chain-rich insulin fraction, but no reactivity with antisera to insulin, glucagon, or somatostatin. Islet amyloid was purified from two cats and a protein unique to the diabetic and islet amyloid-laden cats was separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Immunoreactivity of this protein with antiserum to the B chain-rich insulin fraction was also shown by immunoblotting. Attempts to obtain the amino acid composition of the purified unique protein (represented by a single 25,000 dalton band on gel electrophoresis) were not successful because the amount of protein was too small. These results provide important additional evidence that an insulin-related protein is involved in the formation of islet amyloid. Our study also shows that the diabetic cat provides several advantages for the continued study of the etiopathogenic relationship of islet amyloid and diabetes mellitus.     

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.     

Feline immunodeficiency virus in Switzerland: clinical aspects and epidemiology in comparison with feline leukemia virus and coronaviruses

Serum samples from 1421 domestic cats (561 healthy, 860 sick) were tested for FIV-, FeLV- and coronavirus infection. The results were stored in a computer data base and compared with epidemiologic data and clinical findings. All 3 infections were significantly more prevalent in sick than healthy cats: FIV was found in 0.7% of healthy and 3.4% of sick cats. For FeLV the prevalence was 3.0% and 13.0% and for coronavirus 21% and 36.2%, respectively. FIV-infected cats were mostly male (73%); no sex predilection was observed in FeLV- and coronavirus infection. In sick cats FIV-infection was significantly more prevalent in cats greater than 2 years of age; no age-dependence was found in FeLV- and coronavirus infections. The prevalence of FIV-infection increased significantly with the number of animals per household. In contrast, the frequency of FeLV infection decreased with the number of animals per household. Prevalence of coronavirus infection did not vary with group size or living conditions. The following clinical symptoms were associated with infection: FIV: general depression, diseases of the urinary tract; FeLV: general depression, fever, rough hair coat, lymphadenopathy, impaired functions of heart and circulation and muscle atrophy; coronavirus: lymphadenopathy and alterations in the abdomen. It was concluded that based on the clinical symptoms alone FIV-infection could not be diagnosed nor differentiated from the other 2 infections.     

Feline immunodeficiency virus infection: a valuable model to study HIV-1 associated encephalitis

Feline immunodeficiency virus (FIV), like human immunodeficiency virus (HIV)-1, is a neurotropic lentivirus and is associated with neuropathology in natural and experimental infections. FIV enters the brain early following experimental infection, and virus has been proposed to enter the brain via the blood–brain barrier and blood–CSF barrier, within infected lymphocytes and monocytes/macrophages. However the entry of cell-free virus or the direct infection of brain endothelial cells and astrocytes of the blood–brain barrier may also contribute to CNS infection. This review explores the role played by the FIV model in the elucidation of mechanism of lentiviral entry to the brain and viral interactions with the CNS, particularly in relation to lymphotropic lentiviruses.     

Feline immunodeficiency. ABCD guidelines on prevention and management

OverviewFeline immunodeficiency virus (FIV) is a retrovirus closely related to human immunodeficiency virus. Most felids are susceptible to FIV, but humans are not. Feline immunodeficiency virus is endemic in domestic cat populations worldwide. The virus loses infectivity quickly outside the host and is susceptible to all disinfectants.InfectionFeline immunodeficiency virus is transmitted via bites. The risk of transmission is low in households with socially well-adapted cats. Transmission from mother to kittens may occur, especially if the queen is undergoing an acute infection. Cats with FIV are persistently infected in spite of their ability to mount antibody and cell-mediated immune responses.Disease signsInfected cats generally remain free of clinical signs for several years, and some cats never develop disease, depending on the infecting isolate. Most clinical signs are the consequence of immunodeficiency and secondary infection. Typical manifestations are chronic gingivostomatitis, chronic rhinitis, lymphadenopathy, weight loss and immune-mediated glomerulonephritis.DiagnosisPositive in-practice ELISA results obtained in a low-prevalence or low-risk population should always be confirmed by a laboratory. Western blot is the ‘gold standard’ laboratory test for FIV serology. PCR-based assays vary in performance.Disease managementCats should never be euthanased solely on the basis of an FIV-positive test result. Cats infected with FIV may live as long as uninfected cats, with appropriate management. Asymptomatic FIV-infected cats should be neutered to avoid fighting and virus transmission. Infected cats should receive regular veterinary health checks. They can be housed in the same ward as other patients, but should be kept in individual cages.Vaccination recommendationsAt present, there is no FIV vaccine commercially available in Europe. Potential benefits and risks of vaccinating FIV-infected cats should be assessed on an individual cat basis. Needles and surgical instruments used on FIV-positive cats may transmit the virus to other cats, so strict hygiene is essential.     

Feline leukemia virus infection and diseases.

Feline leukemia virus is a naturally occurring, contagiously transmitted and oncogenic immunosuppressive retrovirus of cats. The effects of FeLV are paradoxical, causing cytoproliferative and cytosuppressive disease (eg, lymphoma and myeloproliferative disorders vs immunodeficiency and myelosuppressive disorders). In the first few weeks after virus exposure, interactions between FeLV and hemolymphatic system cells determine whether the virus or the cat will dominate in the host/virus relationship--persistent viremia and progressive infection or self limiting, regressive infection will develop. The outcome of these early host/virus interactions is revealed in the diagnostic assays for FeLV antigenemia and viremia. The latter, in turn, predict the outcome of FeLV infection in cats. Known host resistance factors include age and immune system functional status. Known virus virulence factors are magnitude of exposure and virus genotype. Molecular analysis of FeLV strains indicated that natural virus isolates exist as mixtures of closely related virus genotypes and that minor genetic variations among FeLV strains can impart major differences in pathogenicity. The genetic coding regions responsible for cell targeting and specific disease inducing capacity (eg, thymic lymphoma, acute immunosuppression, or aplastic anemia) have been mapped to the virus surface glycoprotein and/or long terminal repeat regions for several FeLV strains. Infection by specific FeLV strains leads to either malignant transformation or cytopathic deletion of specific lymphocyte and hemopoietic cell population, changes that prefigure the onset of clinical illness. Another notable feature of the biology of FeLV is that many cats are able to effectively contain and terminate viral replication, an important example of host immunologic control of a retrovirus infection and a process that can be selectively enhanced by vaccination. Thus, FeLV infection serves as a natural model of the multifaceted pathogenesis of retroviruses and as a paradigm for immunoprophylaxis against an immunosuppressive leukemogenic retrovirus.     

Feline immunodeficiency virus testing in stray, feral, and client-owned cats of Ottawa

Feline immunodeficiency virus (FIV) seroprevalence is evaluated in 3 groups of cats. Seventy-four unowned urban strays were tested, as well as 20 cats from a small feral cat colony, and 152 client-owned cats. Of the 246 cats tested, 161 (65%) were male and 85 (35%) were female. Seroprevalence for FIV was 23% in the urban strays, 5% in the feral cat colony, and 5.9% in the client-owned cats. Ten cats (4%) were also positive for Feline leukemia virus (FeLV) antigen, including 2 cats coinfected with FeLV and FIV. Seroprevalence for FIV in cats from Ottawa is similar to that found in other nonrandom studies of cats in North America.     

Feline panleukopaenia virus and mink enteritis virus. A serological study.

The serological relationship of Danish feline panleukopaenia virus and mink enteritis virus and strains from Great Britain, USA, Germany and Canada was examined in neutralization tests using a direct immunofluorescence technique. Vaccine strains of the virus were used representing virus strains from the different countries. It was found that all Danish feline panleukopaenia virus strains and the mink enteritis strain belong to the same serotype and further that they are of similar antigenicity as feline panleukopaenia virus strains and mink enteritis strains isolated in other countries.     

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.