Hepatitis A virus and polymerase chain reaction amplification: methodology and results

Hepatitis A infection among patients receiving solvent/detergent inactivated factor VIII preparations in various locations in Europe have been documented recently. In investigations in Italy, Germany and Ireland, polymerase chain reaction (PCR) amplification was used to detect hepatitis A virus in frozen plasma pools, purified factor VIII, patient sera and samples from animal transmission studies; nucleic acid sequencing was used to clarify and identify the virus responsible based upon genotype analysis. Unique virus strains were found among the cases in Italy and Germany, and identical virus sequences were also found in some factor VIII lots. However, with the exception of the Italian investigation, lack of appropriate samples have precluded the identification of virus in these outbreaks. In addition, animal infectivity studies have not been successful in demonstrating infectivity under laboratory conditions. We discuss the limitations of PCR amplification with respect to detecting virus within these situations, and the necessity for the corresponding epidemiologic investigations.