Investigations of porcine circovirus type 1 (PCV1) in vaccine-related and other cell lines

Abstract

Porcine circovirus type 1 (PCV1) is highly prevalent in swine and was recently reported in some rotavirus vaccines. Since animal-derived raw materials, such as cells, trypsin, and serum, can be a major source of introducing virus contamination in biological products, we have investigated PCV1 in several cell lines obtained from ATCC that have broad use in research, diagnostics, or vaccine development. It is expected that these cell lines have been exposed to bovine and porcine viruses during their establishment and passage history due to the use of serum and trypsin that was not qualified according to current testing guidances or processed using new virus-inactivation methods. This study showed that Vero, MRC-5, and CEFs, which represent cell substrates used in some U.S. licensed vaccines, and other cell lines used in investigational vaccines, such as MDCK, HEK-293, HeLa, and A549, were negative for PCV1 using a nested PCR assay; some were also confirmed negative by infectivity analysis. However, MDBK cells, which are used for some animal vaccines, contained PCV1 sequences, although no virus was isolated. Although the results showed that PCV infection may not have occurred under previous culture conditions, the recent cases of vaccine contamination emphasizes the need for continued efforts to reduce the likelihood of introducing viruses from animal-derived materials used in product manufacture.