MONITORING OF EARLY EVENTS OF EXPERIMENTAL WOODCHUCK HEPATITIS INFECTION - STUDIES OF PERIPHERAL-BLOOD MONONUCLEAR-CELLS BY CYTOFLUOROMETRYAND PCR

The peripheral blood mononuclear cells (PBMC) of woodchucks experiment ally infected by woodchuck hepatitis virus (WHV) were examined simulta neously for the present of membrane associated WHV antigens by cytoflu orometry, and for WHV DNA and RNA sequences hy the polymerase chain re action (PCR). Four woodchucks were inoculated: two with a well-defined infectious inoculum and two with an inoculum obtained from an animal at the late incubation phase, which was positive for WHV DNA by PCR bu t still devoid of WHV markers. Infection was demonstrated in all four inoculated woodchucks by the appearance at different times of WHV DNA and WHV antigens in both leucocytes aad serum. WHV DNA was first detec ted by PCR either in the serum (two cases) or in leucocytes (two cases ). The mean percentage of cells positive for membrane associated WHsAg or WHcAg detected by cytofluorometry were 37%+/-25 and 17%+/-15 respe ctively. After 8 weeks, all inoculated animals were WHsAg positive in serum. These data suggest that PBMC are involved in the early events o f hepadavirus infection. They also show that sera which are positive b y PCR for WHV DNA may transmit viral infection even while still serone gative for WHV markers and for WHV DNA by dot blot.