Kinetics of duck hepatitis B virus infection following low dose virus inoculation: one virus DNA genome is infectious in neonatal ducks.

摘要

Newly hatched ducklings were inoculated with pooled serum from ducks congenitally infected with duck hepatitis virus (DHBV) containing 9.5 X 109 genomes/ml. Infectivity titre (ID50) was 1.5 X 1010/ml indicating that one genome represents one infectious unit. The incubation time for infection was inversely related to dose with onset of viraemia on day 6 at the highest dose and days 14 or 29 for the lowest dose. Using doses (1.5 X 103 ID50 i.v.) low enough to infect only 0.0001% of hepatocytes, it was shown that the mean doubling time for infection was 16 h during days 4-14 after infection when >95% of hepatocytes were infected. These findings indicate that adaptive defense mechanism during the first 10-14 days are insufficient to contain virus spread and that virus replicating in a small number of hepatocytes can rapidly infect the remaining hepatocytes.