EQUINE INFECTIOUS-ANEMIA VIRUS - EVIDENCE FAVORING CLASSIFICATION AS A RETRA-VIRUS

Equine infectious anemia virus (EIAV) has a density of 1.154 g/cm3 in sucrose, a high MW RNA similar in size to Rauscher murine leukemia virus and an internal virion reverse transcriptase that utilizes the synthetic RNA template poly(rA) but not the synthetic DNA template poly(dA), both with (dT)12 as primer. Although capable of utilizing Mn at low concentrations (approximately 0.1 mM), EIAV reverse transcriptase showed highest activity in the presence of 9 mM Mg. The major protein of EIAV has a slightly lower MW than the comparable protein of type C viruses and coelectrophoresed with 125I-labeled p25 of Mason-Pfizer monkey virus. A reference horse serum with antibodies to the major EIAV protein reacted only with EIAV and not with other type C or non-type C retraviruses. Reciprocally, a broadly reactive serum to type C virus p30s and specific sera to a variety of non-type C retraviruses did not react with EIAV. The inclusion of EIAV in the family Retraviridae is recommended.