Measuring the Humoral Immune Response in Cats Exposed to Feline Leukaemia Virus

Abstract

Retroviruses belong to an important and diverse family of RNA viruses capable of causing neoplastic disease in their hosts. Feline leukaemia virus (FeLV) is a gammaretrovirus that infects domestic and wild cats, causing immunodeficiency, cytopenia and neoplasia in progressively infected cats. The outcome of FeLV infection is influenced by the host immune response; progressively infected cats demonstrate weaker immune responses compared to regressively infected cats. In this study, humoral immune responses were examined in 180 samples collected from 123 domestic cats that had been naturally exposed to FeLV, using a novel ELISA to measure antibodies recognizing the FeLV surface unit (SU) glycoprotein in plasma samples. A correlation was demonstrated between the strength of the humoral immune response to the SU protein and the outcome of exposure. Cats with regressive infection demonstrated higher antibody responses to the SU protein compared to cats belonging to other outcome groups, and samples from cats with regressive infection contained virus neutralising antibodies. These results demonstrate that an ELISA that assesses the humoral response to FeLV SU complements the use of viral diagnostic tests to define the outcome of exposure to FeLV. Together these tests could allow the rapid identification of regressively infected cats that are unlikely to develop FeLV-related disease.

Infektion mit dem felinen Leukämievirus – der Weg zur Diagnose

“…2 , Tab. 1 ) 14 , 21 , 28 , 29 . Im Gegensatz zu progressiv infizierten Katzen kommt es bei regressiv infizierten Katzen meist nur am Anfang einer Infektion oder nach Reaktivierung zur Virämie.…”

News & Views

“…In this study, humoral immune responses were examined in 180 samples collected from 123 domestic cats that had been naturally exposed to FeLV, using a novel ELISA to measure antibodies recognising the FeLV-A and FeLV-B SU glycoproteins in plasma samples. 8 Exposure outcomes were assigned based on FeLV test results (p27 capsid antigen in plasma, peripheral blood mononuclear cells [PBMCs] proviral DNA qPCR and PBMC virus isolation). 8 Samples from cats with progressive infection displayed statistically higher p27 capsid antigen concentrations in plasma and higher proviral loads in PBMCs compared with cats with regressive infection, consistent with efficient viral replication.…”

“…8 Exposure outcomes were assigned based on FeLV test results (p27 capsid antigen in plasma, peripheral blood mononuclear cells [PBMCs] proviral DNA qPCR and PBMC virus isolation). 8 Samples from cats with progressive infection displayed statistically higher p27 capsid antigen concentrations in plasma and higher proviral loads in PBMCs compared with cats with regressive infection, consistent with efficient viral replication. The strength of the humoral immune response to the SU protein correlated with the outcome of exposure.…”

Vaccination and Antibody Testing in Cats

“…Results of a recent study on the humoral immune response in cats with regressive or progressive FeLV infection also support a role for VNAs in protection. VNAs were only detected in the cats with regressive infections, and these cats also showed higher FeLV-antibody responses against the surface protein (gp70) compared to cats with progressive infections [ 16 ].…”