No abstract

The herpes simplex virus (HSV) recombinant R7017 was constructed from HSV-1 (strain F) by deleting a portion of the thymidine kinase (tk) gene and by replacing the sequences representing the internal inverted repeats and adjacent genes in the L component with a fragment of the HSV-2 genome encoding the glycoproteins G, D, I, and a portion of E. In addition, the R7020 recombinant contains an HSV-1 DNA fragment encoding the tk gene fused to the alpha 4 gene promoter. The results of studies in mice, guinea pigs, and rabbits were as follows: Both recombinants remained unchanged after nine serial, intracerebral passages in mice; the recombinants could not be differentiated with respect to attenuation in mice injected intracerebrally, in vaginally infected guinea pigs, and in rabbits inoculated on the scarified cornea. Given intradermally or intramuscularly, the recombinants prevented severe infections by virulent challenge viruses, and R7020 established latent infections (at a low frequency) in all species tested, whereas latent R7017 virus was detected in rabbits only.

No abstract

R325-lTK+, a herpes simplex virus 1 mutant carrying a 500-base-pair deletion in the a22 gene and the wild-type (,) thymidine kinase (TK) gene, was previously shown to grow efficiently in HEp-2 and Vero cell lines. We report that in rodent cell lines exemplified by the Rat-1 line, plating efficiency was reduced and growth was multiplicity dependent. A similar multiplicity dependence for growth and lack of virus spread at low multiplicity was seen in resting, confluent human embryonic lung (HEL) cells. The shutoff of synthesis of 0 proteins was delayed and the duration of synthesis of y proteins was extended in R325-PTK+-infected HEL cells relative to cells infected with the wild-type parent, but no significant differences were seen in the total accumulation of viral DNA. To quantify the effect on late (Y2) gene expression, a recombinant carrying the deletion in the a22 gene and a 'y2-TK gene (R325-Y2TK) was constructed and compared with a wild-type virus (R3112) carrying a chimeric y2-TK gene. In Vero cells, the Y2-TK gene of R325-y2TK was expressed earlier than and at the same level as the y2-TK gene of R3112. In the confluent resting HEL cells, the expression of the 'y2-TK gene of the a22-virus was grossly reduced relative to that of the at22+ virus. Electron microscopic studies indicated that the number of intranuclear capsids of R325-,TK' virus was reduced relative to that of

The genetically engineered herpes simplex virus strains R7017 and R7020 were tested in owl monkeys (Aotus trivirgatus) previously shown to model herpetic diseases of immunocompromised patients and neonates. In contrast to the lethal disease seen in monkeys receiving 100-1,000 plaque-forming units (pfu) of wild-type virus, inoculation of greater than or equal to 10(6) pfu of recombinant viruses produced local lesions and viral shedding but not disseminated disease. Latent recombinant viruses were recovered from some ganglia innervating the sites of inoculation. Monkeys protected from lethal infection with wild-type virus exhibit recurrent lesions that increase in frequency and severity after total lymphoid gamma irradiation (TLI). In contrast, monkeys immunosuppressed by TLI and inoculated with R7020 could not be differentiated from irradiated controls with respect to morbidity or mortality. Moreover, the virus was not transmitted from immunosuppressed infected females to normal male cage mates.