Productive infection of human hepatocellular carcinoma cells by porcine circovirus type 1

Porcine circovirus type 1 (PCV1), a small DNA virus in pigs, recently gained its notoriety when commercial human rotavirus vaccines were discovered to be contaminated by infectious PCV1. Here we report, for the first time, definitive evidence of productive PCV1 infection in a subclone of human hepatocellular carcinoma cell line (Huh-7, subclone 10-3). Infectious virus was detected in the lysates of infected Huh-7 cells by immunofluorescent assay (IFA) and can be serially passaged in Huh-7-S10-3 cells. The growth kinetic of PCV1 in Huh-7-S10-3 cells was determined in a one-step growth curve using IFA and a quantitative PCR assay. PCV1 achieved a lower infectious titer in Huh-7-S10-3 human cells compared to the titer normally achieved in porcine PK-15 cells from published studies. While the direct relevance to vaccine safety of PCV1 growth in human hepatocellular carcinoma cells is unclear, these data should be considered in further evaluation of vaccines and other products that could contain infectious PCV1.