| Abstract: | A novel, simple method of infectious center assay was developed to detect and quantitate the intracellular existence of equine herpesvirus 1 and equine herpesvirus 2 in peripheral blood mononuclear cells infected in vivo and in vitro with the viruses by cocultivation of these cells with a permissive equine cell culture. The infectious center titers were correlated with the infectious virus titers. In vivo equine herpesvirus 1-infected mononuclear cells obtained from ponies experimentally infected with the virus and equine herpesvirus 2-infected mononuclear cells obtained from selected naturally infected ponies with the virus gave by infectious center assay a mean value of 67 infectious center/2 x 106 cells as a peak titer on day 4 postinfection and 26 infectious center/2 x 106 cells for equine herpesvirus 1 and equine herpesvirus 2 respectively. The mononuclear cells, in both cases, did not contain detectable infectious virus, but the infectious virus was detected from the respective cells when they were cultured in the presence of mitogen. The equine herpesvirus 1 infected mononuclear cells in culture gave a mean count of 8.05 x 102 infectious center/2 x 106 cells/mL and contained 1.08 x 104 plague assay/mL of infectious virus. Similarly the equine herpesvirus 2 infected mononuclear cells in culture gave a mean count of 7.1 x 101 infectious center/2 x 106 cells/mL and contained <101 tissue culture infective dose50/mL of infectious virus. Mononuclear cells infected in vitro with equine herpesvirus 1 gave a mean count of 9.3 x 104 infectious center/2 x 106 cells/mL and contained 5.75 x 103 plaque assay/mL of infectius virus. Culturing these cells in the presence of mitogen gave a mean count of 5.5 x 103 infectious center/2 x 106 cells/mL and contained 9 x 103 plague assay/mL of infectious virus. A correlation between infectious center assay and infectious virus assay is discussed. |
