HSV-1 retinitis and delayed hypersensitivity in DBA/2 and C57BL/6 mice

Area of Science:

• Ophthalmology
• Immunology
• Virology

Background:

• Herpes Simplex Virus type 1 (HSV-1) inoculation into the anterior chamber (a.c.) of BALB/c mice causes pan-retinal inflammation and anterior chamber-associated immune deviation (ACAID).
• ACAID is characterized by impaired virus-specific delayed hypersensitivity (DH) responses.

Purpose of the Study:

• To investigate whether different mouse strains (DBA/2 and C57BL/6) develop ACAID and contralateral retinitis following a.c. inoculation of HSV-1.
• To correlate the development of retinitis with viral load and immune status in different strains.

Main Methods:

• Uniocular anterior chamber inoculation of HSV-1 (KOS strain) into DBA/2 and C57BL/6 mice.
• Clinical examination for contralateral retinitis at intervals post-inoculation.
• Virus recovery from uninoculated eyes.
• Ear challenge for delayed hypersensitivity (DH) assays to assess HSV-1 specific immune response.

Main Results:

• DBA/2 mice exhibited clinical signs of retinitis in the uninoculated eye in 7/15 cases by day 10 post-inoculation, with an average viral titer of 3.37 log10 PFU/ml.
• DBA/2 mice also showed significantly impaired HSV-1 specific DH responses, consistent with ACAID.
• C57BL/6 mice did not develop contralateral retinitis (0/12), with a lower average viral titer (1.10 log10 PFU/ml) in uninoculated eyes at day 10.
• C57BL/6 mice maintained vigorous DH responses post-a.c. inoculation, comparable to controls.

Conclusions:

• Mouse strain significantly influences susceptibility to HSV-1 induced retinitis and ACAID development.
• The extent of viral replication in the uninoculated eye correlates with the development of contralateral retinitis.
• C57BL/6 mice are more resistant to HSV-1 retinitis and ACAID compared to DBA/2 mice.