An improved method for detection of ganglionic latency in herpes simplex virus type-1 infected guinea pigs

Herpes simplex virus as a transneuronal tracer

Determining the connections of neural systems is critical for determining how they function. In this review, we focus on the use of HSV-1 and HSV-2 as transneuronal tracers. Using HSV to examine neural circuits is technically simple. HSV is injected into the area of interest, and after several days, the animals are perfused and processed for immunohistochemistry with antibodies to HSV proteins. Variables which influence HSV infection include species of host, age of host, titre of virus, strain of virus and phenotype of infected cell. The choice of strain of HSV is critically important. Several strains of HSV-1 and HSV-2 have been utilized for purposes of transneuronal tract-tracing. HSV has been used successfully to study neuronal circuitry in a variety of different neuroanatomical systems including the somatosensory, olfactory, visual, motor, autonomic and limbic systems.

Anterograde transport of HSV-1 and HSV-2 in the visual system

The anterograde spread of herpesvirus in the visual system subsequent to retinitis has been observed clinically. We compared the ability of two well-studied Herpes simplex virus (HSV) strains to be transported in the anterograde direction in the hamster visual system: strain McIntyre, representing HSV-1, and strain 186, representing HSV-2. Intravitreal injection of HSV-2 labeled more retinorecipient neurons than did HSV-1, suggesting important type differences in the ability of HSV to infect retinorecipient neurons after intravitreal injection. The most likely explanation for our results is that HSV-2 is more efficiently adsorbed than HSV-1 in the retinal ganglion cells. Our results also suggest that HSV may be useful as an anterograde transneuronal tracer for neuroanatomical studies of the visual system.

Antiviral activity of a D-glucosamine derivative against herpetic ulcers (HSV type 2) in rabbit cornea

Although most herpetic ocular infections in adults are caused by herpesvirus hominis type 1, several cases of culture proved HSV-2 ocular infection in adults have been described, with more severe and prolonged disease. In a screening for new antiherpetic compounds, we investigated the efficacy in vivo of a new compound, nitroderivative of D-glucosaminhydrochloride (GN-11) in comparison with D-glucosaminhydrochloride (GN), Acyclovir (ACV) and placebo against herpetic keratitis of herpes simplex type 2 in 4 x 4 eyes from 4 x 4 rabbits, respectively. ACV and GN-11 showed similar results. The treatment with GN-11 retarded the appearance of herpetic lesions, which were small and diffuse in comparison with the placebo group. A total recovery was obtained on the 12th day of the treatment. In the ACV treated group, a minimal number of small lesions appeared, but the eyes recovered normality on the 7th day of treatment. The appearance of acute herpetic keratitis was prevented by GN-11. Placebo and GN treated groups showed similar evolution, with lost vision and neurological involvement on the 7th day of infection.

The pathogenesis of herpetic ocular disease in the guinea pig

A detailed study of the pathogenesis of herpetic eye disease in the guinea pig was undertaken to further develop this animal model. Several well-known HSV-1 strains were tested for their ability to produce disease and cause acute and latent infections of the trigeminal ganglion: McKrae, KOS, McIntyre, RE, and Shealey. Two HSV-2 strains failed to cause eye infections. The Shealey strain [HSV-1 (Sh)] produced the most severe eye infections, characterized by epithelial and stromal disease, corneal vascularization and ulcerative blepharitis. Consequently, HSV-1 (Sh) was selected as the prototype strain for this study. The frequency and severity of HSV-1 (Sh) eye disease patterns was determined by a semi-quantitative rating scale, which permitted accurate monitoring of the temporal development of the disease patterns cited above. Virus shedding from infected eyes was also quantified. All of the HSV-1 strains tested established trigeminal ganglionic latency with varying frequency, although HSV-1 (Sh) latency approached 100 percent. The kinetics of acute ganglionic infection by HSV-1 (Sh) was determined, and peak virus titers occurred on the third day after corneal inoculation. This study emphasizes the usefulness of the Guinea pig model for investigations on the pathogenesis, prevention and treatment of herpetic eye infections.