Testing for viral contaminants of veterinary vaccines in Hungary

The safety of veterinary vaccines is of paramount importance and it is significantly jeopardised by extraneous agents such as bacteria, mycoplasma, Chlamydia and viruses. Several critical steps of vaccine manufacture involve a potential risk of viral contamination. Viruses, as extraneous, agents can be divided into two main groups. Group 1 agents, such as Pestivirus, chicken anaemia virus (CAV), and egg drop syndrome virus (EDSV) are well-known to manufacturers and authorities. Compendial detection methods, clear guidelines and legislation have been established to minimise the risk of contamination with these agents. Contrary to group 1, group 2 agents like Torque Teno virus (TTV) or RD114, a replication-competent feline γ-retrovirus, have only recently been recognised and their role as contaminants needs further investigation. Randomly selected veterinary vaccines used between 1992 and 2009 were tested by nucleic acid amplification for CAV, EDSV, and TTV. Pestivirus contamination was examined in 33 vaccines used between 1996 and 2006 and a further 27 vaccines used between 2007 and 2009 based on random selection of these vaccines. In addition to random tests done on vaccines used from 2007 on, 12 batches of live Aujeszky's disease vaccines submitted to our laboratory for Official Control Authority Batch Release (OCABR) were also tested for Pestivirus.