Serologic and molecular comparisons of several equine herpesvirus type 1 strains

The molecular and serologic relatedness of 2 recent respiratory tract isolates of equine herpesvirus type 1, designated T1 and T2, were compared with the Army 183, Kentucky-A hamster-adapted (KyA-ha), and L-M cell-adapted (KyA-LM) strains. Electrophoresis in polyacrylamide gels revealed differences in virion structural proteins among 4 purified strains. Seven envelope glycoproteins (molecular weight of 93,000, 65,000, 62,000, 60,000, 36,000, 20,000, and 18,000) corresponding to virion proteins 13, 16, 17, 18, 23, 25, and 26a, respectively, found in both the Army 183 and KyA-ha strains had slightly different molecular weight counterparts in both the T1 and T2 isolates, which had identical structural protein profiles. virion protein 19 (58,000 daltons), a nonglycosylated protein, was present in reduced amounts in the respiratory tract isolates, whereas virion protein 8a (200,000 daltons) was absent. Virion protein 8a, an envelope glycoprotein, was only present in the KyA-ha strain. The T1 and T2 isolates were not neutralized by equine herpesvirus type 2 antiserum and revealed little cross-neutralizatio with the Army 183 and KyA-ha strains in plaque-reduction neutralization tests. Restriction endonuclease cleavage maps of viral DNA revealed a similar, but not identical, number and size of DNA fragments between T1 and T2 isolates. Likewise, DNa profiles of Army 183, KyA-ha, and KyA-LM were also similar to each other, but vastly different from the respiratory tract isolates.