Determination of Herpes Simplex Virus Isotypes by Nested Polymerase Chain Reaction

Herr, Hwan; Kim, Young Tae; Choi, Tae Yeal

Abstract

BACKGROUND: Polymerase chain reaction(PCR) was developed to diagnose viral infections such as herpes simplex virus(HSV) more rapidly and accurately than the culture technique. Nested PCR, with knowingly higher sensitivity and specificity than the conventional PCR, has been recently applied to determine HSV isotyping.
OBJECTIVE
We conducted this study to compare the prevalence of each HSV isotype among patients with HSV infections by nested PCR in relation to different age groups and body sites.
METHODS
Specimens were collected with cotton-swabs from the lesions, and then snap frozen, and stored at -70 degrees C in a deep freezer until processed. They were innoculated into the monolayer of Vero(African green monkey kidney) cells, and later examined for cytopathic effects. DNAs were extracted from each specimen and were amplified by using nested PCR with the primers against the genes encoding gpD of HSV-1 and HSV-2, respectively.
RESULTS
Of 127 patients, who had been diagnosed as HSV infections by the culture technique, all cases were positive in the nested PCR method. The positive cases of each isotype for HSV-1, HSV-2 and mixed infections (HSV-1 & HSV-2) were 77 (61%), 36 (28%) and 14 (11%), respectively. The prevalence of infections with HSV-1 in the age group under 19 years old was significantly higher than that in the age group over 20 years old (p<0.05). The prevalence of infections with HSV-2 in the age group over 20 years old was significantly higher than that in the age group under 19 years old (p<0.05). There was a close correlation between the HSV isotypes and their predilection sites of the body, showing HSV-1 for area above the waist including lips, oral cavity, eyes, face, fingers and chest, otherwise HSV-2 and mixed infections for area below the waist including genital organs and buttocks (p<0.001).
CONCLUSION
It was suggested that the prevalence of each HSV isotype in certain age groups of the patients might be somewhat different from those reported in other studies. The affinity of HSV isotypes to the specific sites of the body was reconfirmed. This study indicated that nested PCR might be a relatively rapid and cost-efficient test with very high sensitivity and specificity for HSV isotyping.