A Comparative Study of Pathogenicity and Antigenicity of Four Strains of Herpes Simplex

Abstract

Summary Comparative studies of pathogenicity and antigenicity were made of four strains of herpes simplex in order to investigate some of the differences which may exist between strains of a single viral species. Mice, rabbits, guinea pigs, white rats, hamsters, cotton rats and chick embryos were observed after inoculation of mouse brain emulsions by various routes. Although herpes simplex is a pantropic virus, differences between strains are accentuated by certain tests. Thus, death of the majority of animals following corneal infection of the rabbit or intranasal inoculation of the cotton rat can be used to indicate strains with prominent neurotropic tendencies, while marked local reactions after intradermal injection of the guinea pig are indicative of dermatotropism. These distinctions probably hold only for the particular species of animals and routes tested, as the strain which was most dermatotropic in our laboratory, “O”, was the cause of fatal encephalitis in a human being. It is not known whether these differences in potentiality of herpes strains are of epidemiologic significance. The development of neutralizing antibodies in rabbits after corneal and intra-abdominal inoculations was studied. Significant levels of antibody were present by three weeks and peak titers were attained by six weeks. The serologic relationships were investigated by testing the corneal reactivity of immunized rabbits to homologous and heterologous strains and by cross neutralization tests in mice and chick embryos. The chick embryo tests were found to be the most sensitive and satisfactory for this purpose.