Feline leukaemia virus (FeLV)
infection in felids results mainly from oronasal exposure to infectious saliva and nasal secretions, but the potential for viral transmission through faeces and urine has not been completely characterized. In order to assess and compare potential FeLV transmission routes, we determined the viral kinetics in plasma, saliva, faeces and urine during early experimental FeLV
infection (up to week 15 post-exposure) in specific pathogen-free cats. In addition to monitoring
p27 antigen levels measured by ELISA, we evaluated the presence of infectious particles by cell culture assays and quantified
viral RNA loads by a quantitative real-time TaqMan polymerase chain reaction.
RNA load was associated with
infection outcome (high load-progressive
infection; low load-regressive
infection) not only in plasma, but also in saliva, faeces and urine. Infectious virus was isolated from the saliva, faeces and urine of infected cats with progressive
infection as early as 3-6 weeks post-
infection, but usually not in cats with regressive
infection. In cats with progressive
infection, therefore, not only saliva but also faeces and to some extent urine might represent potential FeLV transmission routes. These results should be taken into account when modelling FeLV-host interactions and assessing FeLV transmission risk. Moreover, during early FeLV
infection, detection of
viral RNA in saliva may be used as an
indicator of recent virus exposure, even in cats without detectable antigenaemia/viraemia. To determine the clinically relevant outcome of FeLV
infection in exposed cats, however,
p27 antigen levels in the peripheral blood should be measured.