Abstract
In 2010, Rotarix was found to be contaminated with infectious porcine circovirus type 1 (PCV1). In China, the Lanzhou lamb rotavirus (LLR) vaccine is the only vaccine used to prevent rotavirus disease. From 2006 to September 2014, more than 54 million doses of LLR vaccines have been lot released. It is a safety issue whether PCV1 is present in the LLR vaccine. Although the cell substrate of LLR, bovine kidney (BK), is different from that of Rotarix, we have investigated the cell’s permissivity for PCV1 by both infectivity and full-length PCR analysis. We have assessed the LLR using a quantitative PCR (qPCR) assay. A total of 171 random batches of LLR final products over a period of 5 years were tested, and no PCV1 was detected (0/171). Infectivity studies showed that two strains of PCV1, the PCV1-prototype, which was derived from PK-15 cells, and the mutant, PCV1-GSK, which was isolated from Rotarix, were capable of replicating in BK cells over a wide m.o.i. ranging from 10 to 0.01. After culture for 6 days, copies of PCV1-prototype DNA were higher than those of PCV1-GSK on average. The genome of the virus was detected at 6 days post-infection. In summary, the LLR vaccine is free of PCV1. Nevertheless, because PCV1 can replicate in the BK cell substrate, manufacturers need to be vigilant in monitoring for this adventitious agent.
Highlights
In 2010, porcine circovirus type 1 (PCV1) was discovered in Rotarix [1]
BLAST results showed that the PCV1-prototype was the same genome as that previously reported for PCV1 in PK-15 cells (GenBank accession number: JN133303.1), while the genome of PCV1-GSK was identical to the PCV1 in Rotarix (GenBank accession number: HM143844.1)
According to the data 6 days p.i., positive signals were detected from the infection with 106 copies mlÀ1 (m.o.i.=10) and 103 copies mlÀ1 (m.o.i.=0.01), which means that a small quantity of PCV1 could be enough to infect the bovine kidney (BK) cells
Summary
In 2010, porcine circovirus type 1 (PCV1) was discovered in Rotarix [1]. It turned out that the Vero cell lines used to manufacture the vaccine were contaminated with porcine circovirus (PCV) [3] and arose most likely from the porcine trypsin used in the propagation of the Vero cells. PCV was first described as an unexpected contamination in the PK-15 (porcine kidney cells) cell line [4]. PCV DNA has been detected in 5 % of stool samples from US adults [1]. In another study which investigated whether PCV2 sequences could be detected in the stool of recipients of RotaTeq (which is contaminated with PCV2 DNA), 235 out of 826 samples (28.5 %) from 59 vaccine recipients were positive for PCV2 DNA [6]. Neither PCV1 nor PCV2 is known to be pathogenic in humans [1, 7, 8]
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