Re-examination of feline leukemia virus: host relationships using real-time PCR.

The mechanisms responsible for effective vs. ineffective viral containment are central to immunoprevention and therapies of retroviral infections. Feline leukemia virus (FeLV) infection is unique as a naturally occurring, diametric example of effective vs. ineffective retroviral containment by the host. We developed a sensitive quantitative real-time DNA PCR assay specific for exogenous FeLV to further explore the FeLV-host relationship. By assaying p27 capsid antigen in blood and FeLV DNA in blood and tissues of successfully vaccinated, unsuccessfully vaccinated, and unvaccinated pathogen-free cats, we defined four statistically separable classes of FeLV infection, provisionally designated as abortive, regressive, latent, and progressive. These host-virus relationships were established by 8 weeks post-challenge and could be maintained for years. Real-time PCR methods offer promise in gaining deeper insight into the mechanisms of FeLV infection and immunity.