SIMILARITY AND DIFFERENCE GENES FOR NONST RUCTURAL NSP2 AND STRUCTURAL-C AND E2 PROTEINS OF WESTERN EQUINE ENCEPHALOMYELITIS VIRUSES

Genetic relationships of geographical isolates of the members of WEE v irus serocomplex (McMillan, Fort Morgan, Highlands J, and Y62-33) were assessed by the polymerase chain reaction (PCR) and restriction analy sis of the PCR products. Oligonucleotide primers (21 nucleotides in le ngth) were chosen for NSP2, nucleocapsid C, and E2-E1 protein genes ba sed on the known primary structure of the McMillan 16310-5614 genome ( L. Uryvayev et al., 1994, 1995). These primers were shown to different iate well the WEE and SV-like strains of the serocomplex. Y62-33 virus (Udmurtia, Russia) was identical to McMillan strain in three studied regions of NSP2, C, and E2-E1 genes. NSP2 gene could be detected in al l the studied geographical isolates and was characterized by the same restriction patterns as endonucleases; it appeared to be the most cons ervative. The structural genes were less conservative. Fort Morgan vir us (Colorado, USA) genome reliably differed from McMillan virus (Calif ornia, USA) and was negative in PCR with primers to C and E2 gene regi ons. Highlands J genome (Florida, USA) was positive in PCR with the pr imers to E2-E1 gene regions but differed from McMillan strain by the n ucleocapsid gene. An additional comparative PCR analysis of the C-E2 r egion in the McMillan and Highlands J genomes showed some, but not com plete identity. The origin of these two viruses might be due to the se lection of different forms of recombinant viruses. A good correlation of structural genes in PCR and the infectivity neutralization test was noted with the primers and polyclonal antibodies to the closely relat ed strains. High specificity of PCR permits a more accurate detection of the virus origin and relationships.