More than fifty albino rabbits were inoculated into the right scarified cornea with 10(7) PFU of the Kupka strain of human herpes virus type 1 (HHV-1). At intervals ranging from 4--280 days post infection (p.i.), both gasserian ganglia, both trigeminal nerve trunks and pieces from brain stem and from both corneas were explanted. Activation of the latent HHV-1 was found mainly in the homolateral ganglion tissue, but also in explants originating from the opposite ganglia. Within 24--72 hours, prior to the release of virus into the medium, one infectious unit of HHV was recovered from 10(4)--10(5) cells of the ganglion explant. In addition, a few neurons and satellite cells revealed the presence of virus-specific antigens when the explants were examined by immunofluorescence in serial sections. If the gangia were explanted in the presence of immune serum, the virus recovery rate was at least twice lower as compared to the virus activation in explants kept in the absence of immune serum.

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Ribonuclease activiy was found associated with plasma membranes isolated from chick embryo chorioallantoic cells. The enzyme was solubilized with buffered 1% Triton X-100 and purified 40-fold by 1-butanol extraction and gel-filtration on Sephadex G-100. The purified Rnase was found to be free of deoxyribonuclease, alkaline phosphatase and decyclizing 2',3'-phosphodiesterase activities. the enzyme is capable to degrade RNA and polycytidylic acid into acid-soluble oligonucleotides terminated in 3'-phosphate. No nucleoside monophosphates and 2',3'-cyclic nucleoside monophosphates were detected. The optimal pH of RNA and poly C hydrolysis were 7.2 and 7.8, the optimal temperatures 60 and 45°C, respectively. The purified enzyme is thermolabile, and it requires monovalent cations for the full enzyme activity.

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