The herpes simplex virus type 1 (HSV-1) glycoprotein K(gK) is essential for viral corneal spread and neuroinvasiveness

Purpose: To determine the role of herpes simplex virus-1 (HSV-1) glycoprotein K(gK) in corneal infection, neuroinvasion, and virus latency in trigeminal ganglia of mice. Methods: The recombinant virus HSV-1 (McK-rae) Delta gK (MK Delta gK) carrying a deletion of the gK gene was constructed by insertional/deletion mutagenesis and replaced by a gene cassette constitutively expressing the enhanced green fluorescence protein. The gK deletion of the MK Delta gK virus was rescued to produce the wild-type-like virus MKgK. Balb/c mice were infected ocularly with either virus, and the infection pattern in the eye, clinical disease progression, and establishment of viral latency was monitored. Results: Mice infected with the MK Delta gK strain produced in a gK complementing cell line did not exhibit clinical signs when compared with mice infected with the MKgK virus. Direct visualization of infected eyes revealed that the MK Delta gK virus was unable to spread in mouse corneas, while the MKgK rescued virus spread efficiently. Nineteen of 20 scarified and 5/12 unscarified mice infected with the MKgK virus produced infectious virus after coculture with permissive cells, while 0/20 scarified and 0/12 unscarified mice infected with the MK Delta gK virus produced infectious virus. HSV DNA was detected in trigeminal ganglia by PCR in 19/20 scarified and 9/12 unscarified mice inoculated with MKgK, while HSV DNA was detected in the trigeminal ganglia of 3/20 scarified and 0112 unscarified mice inoculated with MK Delta gK. Conclusions: The results show that HSV-1 gK is essential for efficient replication and spread in the corneal epithelium and trigeminal ganglia neuroinvasion in MK Delta gK inoculated mice.