No abstract

Rhesus monkey fetuses were inoculated with Venezuelan Equine Encephalitis (VEE) vaccine virus by the direct intracerebral route at approximately 100 days gestation to determine possible teratogenicity of the virus. Congenital micrencephaly, hydrocephalus and cataracts were found in all animals and porencephaly in 67 percent of the cases. The virus replicated in the brain and other organs of the fetus. VEE vaccine virus is teratogenic for non-human primates and must be considered a potential teratogen of man.

Enterovirus receptors of live HeLa cells have been shown to reappear after inactivation by proteolytic enzymes, provided the cells are incubated at 37 C in a nutritionally adequate medium. Regeneration of receptor activity for poliovirus Ti occurred at a significantly faster rate than for coxsackievirus B3. The regenerative process for both types of receptors studied evidently required an active process of protein synthesis, since it was found that reappearance of receptor activity was inhibited by streptovitacin A, puromycin, and actinomycin D. Substitution of pfluorophenylalanine for the naturally occurring amino acid, at concentrations which inhibited virus synthesis, was without effect on regeneration of receptor activity. It is anticipated that these findings will aid in the study of the biosynthesis and subsequent chemical characterization of viral receptors of living host cells.

Human peripheral blood leukocytes (PBL) were examined for their ability to support growth of several group A arboviruses in vitro. Cells were refractory to infection with eastern (EEE) and western (WEE) equine encephalitis viruses, whereas Venezuelan equine encephalomyelitis (VEE) virus was shown to infect and replicate to a substantially high titer. When PBL were fractionated into purified subpopulations, only the monocytes were susceptible to predictive VEE virus infection. Lymphocytes treated 24 h before virus inoculation with phytohemagglutinin (10 microgram/ml) were capable of propagating significant amounts of VEE virus. A monocytic cell line, J-111, was also susceptible to infection with VEE, EEE, and WEE viruses, whereas a lymphocytic cell line, Raji, was refractory. Additional information on the participation of PBL during human infection with these viruses may add considerably to our understanding of their differing pathogenicities and clinical pictures.

Column chromatography of selected Venezuelan equine encephalomyelitis (VEE) viruses on calcium phosphate gel offered a simple and reproducible method for examination of biochemical characteristics and relatedness of strains within the VEE complex. Members of antigenic subgroup I demonstrated a series of elution profiles within a narrow range of 0.22 to 0.25 M phosphate buffer. Members of antigenic subgroups II, III, and IV differed substantially among themselves and viruses of antigenic subgroup I. These differences in elution behavior may contribute to understanding of observed differences in biological behavior and antigenic variation among VEE viruses.