Antigenic Dissimilarity between Strains of Herpes Simplex Virus

Abstract

In the course of experiments with the virus of herpes simplex, several strains were compared by means of neutralization tests. A significant antigenic difference between some of the strains was demonstrated.

The antiserum used in all the neutralization tests included in the present report represented a pool of single bleedings of each of 2 rabbits, previously infected with one of the strains under consideration. These animals, which were inoculated upon the cornea with strain FE, developed typical keratoconjunctivitis. Encephalitis did not ensue. They were bled from the heart 32 days after inoculation and the serums were pooled. The animals were not hyperimmunized because of the possibility of decreasing the specificity of their serums.

Three strains of herpes virus were included in the study. The HF strain originally isolated from a human lip vesicle in 1922 1 and maintained by brain-to-brain passage in mice was employed in its 213th passage. Strains FE and LH were recently isolated from primary herpetic lesions of the genitalia of 2 adult females. 2 Both of the latter strains were also passed serially by intracerebral inoculation of mice. The 19th intracerebral passage in mice of FE and the 20th of LH were used in the neutralization tests.

Neutralization tests were performed by mixing equal volumes of undiluted immune serum and decimal dilutions of the viruses. All tests, including controls, were done as a single experiment on a single day. Neutralization of each virus was controlled concomitantly by mixing normal rabbit serum (pooled serum of 3 rabbits) with appropriate dilutions of the viruses. After 90 minutes at room temperature and 30 minutes in the refrigerator, the mixtures of serum and virus were tested for neutralization by injecting 0.03 ml quantities intracerebrally in adult mice. The animals were inspected daily and deaths recorded over a period of 17 days.