Vaccinia virus serpins B13R and B22R do not inhibit antigen presentation to class I-restricted cytotoxic T lymphocytes

1 Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE and 2 Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK Vaccinia virus (VV) inhibits the presentation of certain epitopes from influenza virus nucleoprotein (NP), haemagglutinin (HA) and non-structural 1 (NS1) proteins to CD8 + cytotoxic T lymphocytes (CTL) by an unknown mechanism. We have investigated whether VV genes B13R and B22R, which encode proteins with amino acid similarity to serine protease inhibitors (serpins), are involved in this process. Recombinant VVs were constructed which express influenza virus proteins HA, NP or NS1 and which lack serpin gene B13R or both B13R and B22R. The lysis of cells infected with these viruses by influenza virus-specific CD8 + CTL was compared to the lysis of cells infected with viruses expressing both the influenza proteins and the serpin genes. Cytotoxicity assays showed that deletion of the VV serpin genes B13R and B22R and other genes between B13R and B24R did not increase the level of lysis, indicating that these genes are not involved in inhibition of antigen presentation of the epitopes tested. * Author for correspondence. Fax +44 1865 275501. e-mail glsmith@molbiol.ox.ac.uk Present address: CRC Institute for Cancer Studies, University of Birmingham Medical School, Edgbaston, Birmingham B15 2TJ, UK Present address: International Medical Affairs, The Wellcome Foundation Limited, Langley Court, Beckenham, Kent BR3 3BS, UK Received 13 April 1995; accepted 22 May 1995.