A Comparison of New World Alphaviruses in the Western Equine Encephalomyelitis Complex by Immunochemical and Oligonucleotide Fingerprint Techniques

Abstract

We have examined the molecular basis for the observed antigenic differences between isolates of western equine encephalomyelitis (WEE) virus and those of a serologically related alphavirus from the eastern United States designated Highlands J (HJ). The structural proteins of WEE virus isolates have mol. wt. of 55 × 10³ (E₁), 47 × 10³ (E₂) and 33 × 10³ for the nucleocapsid. The E₁ glycoprotein had an isoelectric point (pI) of 6.4 and induced haemagglutination-inhibiting (HI) antibody which was specific for WEE virus. The E₂ glycoprotein of WEE virus had a pI of 8.4 and induced antibody which was virus specific by neutralization (PRNT) but cross-reacted with HJ virus in the radioimmune precipitation (RIP) test. Envelope glycoproteins of HJ virus isolates had mol. wt. of 58 × 10³ (E₁) and 49 × 10³ (E₂) respectively. The E₁ glycoprotein from HJ virus had a pI of 6.8 and induced antibody which reacted specifically in the HI, PRNT and RIP tests. Isolated E₂ protein of HJ virus had a pI of 9.1 and induced antibodies which were reactive at equal titre with both WEE and HJ viruses by RIP.