A recombinant herpes simplex virus type 1 expressing two additional copies of gK is more pathogenic than wild-type virus in two different strains of mice

The effect of glycoprotein K (gK) overexpression on herpes simplex virus type 1 (HSV-1) infection in two different strains of mice was evaluated using a recombinant HSV-1 virus that expresses two additional copies of the gK gene in place of the latency-associated transcript (LAT). This mutant virus (HSV-gK ³) expressed higher levels of gK than either the wild-type McKrae virus or the parental dLAT2903 virus both in vitro (in cultured cells) and in vivo (in infected mouse corneas and trigeminal ganglia [TG] of BALB/c and C57BL/6 mice). gK transcripts were detected in the TG of both HSV-gK ³-infected mouse strains on day 30 postinfection (p.i.), while gB transcripts were detected only in the TG of the HSV-gK³-infected C57BL/6 mice, a finding that suggests that increased gK levels promote chronic infection. C57BL/6 mice infected with HSV-gK³ also contained free virus in their TG on day 30 p.i. Both HSV-gK³-infected mouse strains had significantly higher corneal scarring (CS) than did McKrae-infected mice. T-cell depletion studies in C57BL/6 mice suggested that this CS enhancement in the HSV-gK³-infected mice was mediated by a CD8⁺ T-cell response. Taken together, these results strongly suggest that increased gK levels promote eye disease and chronic infection in infected mice.