Difference in Neutralization Between Lactate Dehydrogenase-elevating Virus Isolated From Acutely and Chronically Infected Mice

Unit of Experimental Medicine, International Institute of Cellular and Molecular Pathology and Université Catholique de Louvain, Avenue Hippocrate 74, B-1200 Brussels, Belgium Mouse infection with lactate dehydrogenase-elevating virus (LDV) leads to lifelong viraemia, despite the production of neutralizing antiviral antibodies. To test whether viral persistence correlated with the development of resistance to these antibodies, we compared the neutralization of viral particles derived from acutely and chronically infected animals, using polyclonal and monoclonal anti-LDV antibodies. Whereas virus isolated during acute infection was efficiently neutralized, titres of LDV from chronically infected mice were only slightly reduced by antiviral antibodies. In addition, LDV from animals acutely infected with such poorly neutralizable virus from chronically infected mice was resistant to anti-LDV antibodies like their parental viral particles. These results suggest that LDV variants capable of escaping neutralization by antiviral antibodies can emerge in chronically infected animals. Received 21 May 1993; accepted 1 December 1993.