Isolation of herpes simplex viruses by chick embryo culture

The chick embryo is a versatile host system in diagnostic virology, especially for isolation of herpes simplex viruses. In this study, samples obtained from 57 clinically diagnosed patients with active herpetic lesions (35 genital & 22 non-genital) were cultured by chick embryo method for isolation of herpes simplex virus. After inoculation onto the chorioallantoic membrane (CAM) of 10-11 days old chick embryo, typical CAM reactions (pocks) appeared in 23(40.3%) samples after 3 days. CAM reactions were identified and typed by direct fluorescence antibody test and 22(95.6%) of 23 isolates gave positive results. Of this, 9(40.9%) were HSV-1 & 13(59.1%) were HSV-2. HSV-1 was isolated from 8(36.4%) of non-genital samples and from 1(7.1%) genital sample. HSV-2 was isolated from 13(92.8%) of genital samples, but none were isolated from non-genital samples. High isolation rate was obtained from vesicular stage of both non-genital (71.5%) and genital (57.1%) samples and from early lesions (sampled within 72 hours) of non-genital (50%) and genital (52.9%) specimen. The chorioallantoic membrane of chick embryo it is a simple, cheap and efficient method of cultivation of some viruses, including HSV. Thus, in settings where cell culture facilities are not available, it can be used for the isolation of herpes simplex viruses from clinical samples.