Different susceptibility of B19 virus and mice minute virus to low pH treatment

BACKGROUND: Parvoviridae are small nonenveloped viruses that are known to be highly resistant to physicochemical treatments. Because low pH is frequently applied to process intermediates or final products, the impact of such conditions on the human erythrovirus B19 (B19V) and the mouse parvovirus (mice minute virus, MMV) was assessed, which is often used as a model for B19V. Owing to the lack of a suitable cultivation and/or detection system for B19V no such data exist so far. STUDY DESIGN AND METHODS: Virus inactivation was monitored by decrease of infectivity and loss of capsid integrity. Infectious B19V was quantified by detection of virus-specific messenger RNA from Ku812Ep6 cells. To measure capsid integrity, endonucleases were added after exposure to low pH and the encapsidated (endonuclease-protected) virus DNA was quantified by real-time PCR. RESULTS: B19V was inactivated greater than 5 log after 2 hours at pH 4, whereas MMV was resistant over 9 hours. Infectivity data strongly correlated with data obtained by the endonuclease assay. Capsid disintegration was observed in immunoglobulin G as well as in different albumin solutions. Temperature and pH showed concerted impact on B19V capsid disintegration. CONCLUSION: Our data show that B19V is much more vulnerable toward low pH conditions than MMV. Together with the previously reported susceptibility of B19V toward wet heat conditions, low pH is the second treatment where erythrovirus B19V is less resistant than viruses from the parvovirus genus.