Isolation, characterization and acyclovir susceptibility of herpes simplex virus isolates among immunocompromised patients

INTRODUCTION: Herpes simplex virus (HSV) Type 2 primarily causes genital herpes, while HSV Type 1 is responsible for oral and facial lesions. The objective of this study was to isolate and characterize HSV from herpetic lesions among human immunodeficiency virus (HIV) infected patients and to evaluate their acyclovir susceptibility pattern. MATERIALS AND METHODS: Blister fluid and swabs from ulcers were collected from patients with clinical diagnosis of HSV infection among patients attending the HIV clinic of two tertiary care centers – Medical College, Kolkata, and School of Tropical Medicine, Kolkata. These samples were cultured in the Vero cell line. Growth of virus was noted by observing the characteristic cytopathic effect of HSV, which was further confirmed by immunofluorescence and polymerase chain reaction (PCR). These isolates were then subjected to the Vero cells with serial dilutions of acyclovir for determining the susceptibility pattern. RESULTS: Among the 52 samples received, 8 (15.38%) showed growth of HSV. After confirmation by immunofluorescence and PCR, all seven isolates from genital samples were identified as HSV-2 and the lone isolate from oral lesion was confirmed as HSV 1. Out of the eight isolates, 25% showed resistance to acyclovir. The overall isolation rate was more from genital blister than genital ulcer which was 46.15% and 2.86%, respectively. CONCLUSION: HSV was isolated in 15.38% of cases of clinical herpes. There was a higher isolation rate of virus from blister fluid as compared to ulcer scrapings. Acyclovir resistance in 25% of cases is alarmingly high.