Uninoculated Eye Research Articles

Uniocular Anterior Chamber Inoculation of a Tumor Necrosis Factor Alpha-Expressing Recombinant of Herpes Simplex Virus Type 1 Results in More Rapid Destruction and Increased Viral Replication in the Retina of the Uninoculated Eye

Tumor necrosis factor alpha (TNF-alpha) has been shown to have a protective role in the eyes and brains of herpes simplex virus type 1 (HSV-1)-infected mice. To determine whether overexpression of TNF-alpha affected the course of virus infection following uniocular anterior chamber inoculation, a recombinant of HSV-1 that produces TNF-alpha constitutively (KOSTNF) was constructed. BALB/c mice were injected with the TNF-alpha recombinant, a recombinant containing the pCI plasmid, a recombinant rescue virus, or the parental virus. Flow cytometry and immunohistochemistry were used to identify virus-infected cells and to determine the numbers and types of infiltrating inflammatory cells in the uninjected eyes. Virus titers were determined by plaque assay. There were no differences among the groups in virus titers or the route and timing of virus spread in the injected eyes or in the suprachiasmatic nuclei. However, in the uninjected eyes of KOSTNF-infected mice, TNF-alpha expression was increased and there were more viral antigen-positive cells and immune inflammatory cells. There was earlier microscopic evidence of retinal infection and destruction in these mice, and the titers of virus in the uninjected eyes were significantly increased in KOSTNF-infected mice on day 7 postinfection compared with those of KOSpCI-, KOS6beta rescue-, or KOS6beta-infected mice. The results suggest that instead of moderating infection and reducing virus spread, overexpression of TNF-alpha has deleterious effects due to increased inflammation and virus infection that result in earlier destruction of the retina of the uninoculated eye.

Two Waves of Virus Following Anterior Chamber Inoculation of HSV-1

Following inoculation of herpes simplex virus type 1 (HSV-1) into the anterior chamber of one eye of a Balb/c mouse, a pattern of ocular retinal disease occurs which is characterized by retinal necrosis, disruption of the retinal architecture of the uninoculated contralateral eye, and sparing of the retina of the virus-inoculated eye. Our direct virus culture studies have revealed that, after uniocular anterior chamber inoculation, virus reaches the uninoculated eye in two temporally separate waves. The first wave of virus is detected in the uninoculated eye as early as one day postinoculation (pi), long before virus is found in either of the optic nerves or the brain. The second wave of virus arrives in this eye between 7 and 10 days pi. Sequentially, the path of the second wave of virus appears to move from the injected eye to (1) the ipsilateral optic nerve, (2) the brain, (3) the contralateral optic nerve, and (4) the posterior segment of the uninoculated contralateral eye, suggesting that interocular spread of the second wave of virus after anterior chamber inoculation occurs via neural pathways. Results of histopathologic examinations and virus culture studies suggest that the early wave of virus contributes to the inflammation observed at the angle structures of the contralateral eye 7–8 days pi and that the second wave of virus accounts for the peak virus titer observed on day 10 pi, a peak which coincides with the destruction of the retina of this eye. It is proposed that the first wave is causally related to the development of retinitis, which occurs as the second wave reaches the retina.

Cytokine Profiles and Inflammatory Cells during HSV-1–Induced Acute Retinal Necrosis

To investigate infiltrating cells, cytokines, and kinetics of cytokine expression during acute retinal necrosis (ARN) in the uninoculated eye after inoculation of herpes simplex virus (HSV)-1 into the anterior chamber of one eye of BALB/c mice. At different time points after inoculation of 2 x 10(4) plaque-forming units (PFU) HSV-1 (KOS strain) or an equivalent volume of Vero cell extract in cell culture medium, the uninoculated eyes were enucleated. RT-PCRs for TNFalpha, IFNgamma, and IL-4 and immunohistochemical staining were performed to identify infiltrating cells and cytokines. Cytometric bead array was used to measure the levels of TNFalpha, IFNgamma, and IL-4 protein. CD4(+) T cells, F4/80(+) macrophages, Gr-1(+) polymorphonuclear cells (PMNs), and CD19(+) B cells were detected in the uninoculated eye of virus-infected mice. Furthermore, RPE65(+) retinal pigment epithelial (RPE) cells and activated Muller cells were also detected in the ARN lesion. TNFalpha, IFNgamma, and IL-4 mRNA and protein were upregulated during the evolution of ARN in HSV-1-infected contralateral eyes compared with levels in control subjects. Immunohistochemistry revealed that cytokines were produced by infiltrating cells as well as by resident retinal cells. The results of these studies support the idea that T cells and cytokines are actively involved in HSV-1 retinitis. They also suggest that PMNs, B cells, and/or macrophages, as well as resident retinal cells, such as RPE and activated Muller cells, also play a role in the pathogenesis of HSV-1 retinitis.

Analysis of Cytokine mRNAs in Murine Herpes Simplex Virus Type 1 Retinitis

Purpose: To investigate cytokine mRNA expression during the inflammatory process induced in the contralateral eyes by uniocular inoculation of herpes simplex virus type 1 (HSV-1) via the anterior chamber. Methods: BALB/c mice were inoculated in the anterior chamber with 5 × 10 4 plaque-forming units of HSV-1 (KOS). mRNA was extracted from the inflamed posterior segments of the uninoculated eyes at 0 (control), 9, 11, 14, and 21 days postinoculation (p.i.). Reverse transcription-polymerase chain reaction was performed for semiquantitative analysis of mRNA expression of interleukin (IL)-1β, IL-2, IL-4, IL-10, IL-12p35, IL-12p40, interferon (IFN)γ, tumor necrosis factor (TNF)α, transforming growth factor (TGF)β2 and induced nitric oxide synthase (iNOS). Results: Peak mRNA expression of iNOS was observed at day 14 p.i. The time profiles of mRNA expression for IL-1β, IL-2, IL-4, IL-10, IFN-γ, TNFα were similar to that of iNOS, while TGFβ2, IL-12p35, and IL-12p40 demonstrated a reverse pattern. Conclusions: The kinetics of the analyzed cytokines synchronized with the clinicopathological activity of the experimental murine HSV-1 retinitis. The immunosuppressive cytokines TGFβ2 and IL-10 demonstrated different peaks of mRNA expressions suggesting that the down-regulation phase of the inflammatory process was controlled by several factors working at different phases.

DNA microarray analysis of the uninoculated eye following anterior chamber inoculation of HSV-1

Purpose: To use DNA microarray to analyze the expression patterns of genes in the uninoculated eye following uniocular anterior chamber inoculation of HSV-1. Methods: On Day 9 following inoculation of 2 × 10 4 PFU of HSV-1 (KOS strain) or an equivalent volume of tissue culture medium into one anterior chamber of BALB/c mice, the uninoculated eyes were enucleated, pooled, and total RNA was isolated. cDNA was synthesized from the total RNA. The gene expression patterns were inferred based on the hybridization intensities of the probes on the cDNA array. The hybridization signals were globally normalized and filtered. The data were analyzed using hierarchical and gene tree clustering algorithms. Additional uninoculated eyes collected on Day 9p.i. were stained for F4/80 and CD19. Results: Compared with the uninoculated eye of control mice, 3800 genes were upregulated at least twofold in the contralateral eye of HSV-1-infected mice. Among the 10 most upregulated genes, T cell-specific protein, MHC II antigen A, and MHC II k region locus 2 were upregulated 179-, 164-, and 162-fold, respectively. Ten T-cell receptor-related genes, 61 cytokine and chemokine genes, and 16MHC genes were upregulated. Furthermore, 11 immunoglobulin and B cell genes and 11 macrophage-related genes were also upregulated. F4/80+ and CD19+ cells were observed on Day 9p.i. Conclusions: The DNA microarray results support the idea that T cells and immunomodulatory factors (cytokines, chemokines) are likely to be involved in HSV-1 retinitis. These results also suggest that B cells and/or macrophages play a role in the pathogenesis of HSV-1 retinitis.

Infiltration of T-lymphocytes in the brain after anterior chamber inoculation of a neurovirulent and neuroinvasive strain of HSV-1

Following anterior chamber (AC) inoculation of BALB/c mice with the KOS strain of herpes simplex virus type 1 (HSV-1), or with H129, a neuroinvasive and neurovirulent strain of HSV-1, both strains of virus spread from the injected eye through the brain to cause retinitis. However, KOS-infected mice develop retinitis in the uninoculated eye only, whereas H129-infected mice develop bilateral retinitis. Previous studies have shown that infiltrating T-cells in the suprachiasmatic nuclei (SCN) of the hypothalamus of KOS-infected mice concomitant with or before virus protect KOS-infected mice from ipsilateral retinitis. To determine the timing of T cell infiltration and cytokine production in the brain of H129-infected mice, adjacent, frozen sections of the brain were immunostained for virus, T-cells, IL-2, TNF-α or IFN-γ. T-cells infiltrated the brains of H129-infected mice and cytokines were produced in infected tissues. However, virus spread to the optic nerve and retina of both the inoculated and uninoculated eye before T-cells and cytokines were detected in the SCN of H129-infected mice. These results suggest that infiltrating T-cells in the SCN of H129-infected mice may arrive too late to prevent the spread of virus into the optic nerves and retinas and thus prevent development of bilateral retinitis in infected mice.

Neuronal pathways for the propagation of herpes simplex virus type 1 from one retina to the other in a murine model.

Herpetic retinitis in humans is characterized by a high frequency of bilateral localization. In order to determine the possible mechanisms leading to bilateral retinitis, we studied the pathways by which herpes simplex virus type 1 (HSV-1) is propagated from one retina to the other after intravitreal injection in mice. HSV-1 strain SC16 (90 p.f.u.) was injected into the vitreous body of the left eye of BALB/c mice. Animals were sacrificed 1, 2, 3, 4 and 5 days post-inoculation (p.i.). Histological sections were studied by immunochemical staining. Primary retinitis in the inoculated eye (beginning 1 day p.i.) was followed by contralateral retinitis (in the uninoculated eye) starting at 3 days p.i. Infected neurons of central visual pathway nuclei (lateral geniculate nuclei, suprachiasmatic nuclei and pretectal areas) were detected at 4 days p.i. Iris and ciliary body infection was minimal early on, but became extensive thereafter and was accompanied by the infection of connected sympathetic and parasympathetic pathways. The pattern of virus propagation over time suggests that the onset of contralateral retinitis was mediated by local (non-synaptic) transfer in the optic chiasm from infected to uninfected axons of the optic nerves. Later, retinopetal transneuronal propagation of the virus from visual pathways may have contributed to increase the severity of contralateral retinitis.

Immune effector cell (IEC)-mediated protection from HSV-1 retinitis occurs in the brain

Following uniocular anterior chamber inoculation of the KOS strain of HSV-1 into euthymic BALB/c mice, virus spreads from the injected eye to the brain and from the brain to the optic nerve and retina of the uninjected eye resulting in retinitis. Adoptive transfer of HSV-1-specific immune effector cells (IEC) within 24 h of anterior chamber inoculation of virus prevents retinitis. To determine where protection occurs, mice were injected with HSV-1 via the anterior chamber route, and fluorescently-labeled HSV-1-specific-IEC or ovalbumin-specific lymph node cells were adoptively transferred intravenously. The eyes and brains of these mice were sectioned and examined for virus-infected cells and for fluorescently-labeled adoptively transferred cells. None of the mice in the group receiving an adoptive transfer of virus-specific IEC had evidence of virus infection of the ipsilateral suprachiasmatic nucleus (SCN), whereas the ipsilateral SCN of all of the mice in the control groups were virus-positive by day 5 P.I. Since virus spreads from the ipsilateral SCN to the contralateral optic nerve and retina to cause retinitis in the uninoculated eye, the results of these studies suggest IEC-mediated protection from HSV-1 retinitis occurs proximal to the ipsilateral SCN. Furthermore, since only HSV-1-specific IEC conferred protection and only these cells were observed in the brain, protection and trafficking of cells after adoptive transfer was virus-specific.

T Lymphocyte infiltration in the brain following anterior chamber inoculation of HSV-1

Following inoculation of the KOS strain of herpes simplex virus type 1 (HSV-1) into one anterior chamber of euthymic BALB/c mice, virus spreads from the injected eye to the central nervous system and from the central nervous system to the optic nerve and retina of only the uninoculated eye. In contrast, in athymic BALB/c mice or mice depleted of both CD4 + and CD8 + T cells, virus spreads to the optic nerve and retina of both the injected eye and the uninjected eye. To determine the location in the central nervous system where spread of virus to the optic nerve and retina of the injected eye is prevented, euthymic BALB/c mice were injected with a mixture of KOS and RH116, a mutant of KOS that contains the Escherichia coli β-galactosidase (β-gal) gene. Several animals were sacrified each day; serial frozen sections of the brain were prepared and sequential sections were stained for β-gal or for T cells. At all sites except the suprachiasmatic nuclei, virus and T cells arrived at approximately the same time. However, at day 5 post inoculation (PI), T cells were present in both the ipsilateral and the contralateral suprachiasmatic nuclei, but only the ipsilateral suprachiasmatic nucleus was virus-positive. Since virus spreads from the ipsilateral suprachiasmatic nucleus to the contralateral optic nerve, these results suggest that T cells infiltrating the area of the contralateral suprachiasmatic nucleus prior to the arrival of virus at this site prevent virus spread into the optic nerve of the inoculated eye.

Induction of bilateral retinal necrosis in mice by unilateral intracameral inoculation of a glycoprotein-C deficient clinical isolate of herpes simplex virus type 1.

Herpes simplex virus can cause acute retinal necrosis, a blinding retinal disease in man. A unilateral intracameral inoculation of herpes simplex virus type 1 (HSV-1) in mice induces retinal necrosis primarily in the contralateral eye and provides an experimental model for the disease. Previous studies suggested that a major envelope glycoprotein of HSV-1, glycoprotein C (gC), is required for retinal necrosis. We studied HSV-1 strain TN-1, a gC-deficient clinical isolated from a lesion of herpetic keratitis, for its pathogenicity in mice with an intracameral inoculation of the virus and found that TN-1 could induce severe necrotizing retinitis in both inoculated and uninoculated eyes of BALB/c mice. Inoculation with a lower dose of TN-1 resulted in a unilateral necrotizing retinitis in the uninoculated eyes. Tissue virus titration of infected mice killed at various times after inoculation detected an infectious virus in various organs including the eyeballs, trigeminal ganglia, brain and adrenal glands. Anterior chamber-associated immune deviation (ACAID) was observed in TN-1-inoculated mice as well as in mice inoculated with gC-positive laboratory strain KOS 7 days postinoculation. Our findings suggested that gC of HSV-1 is not necessary for either the induction of retinal necrosis, neural spread of the virus, or ACAID.

An animal model of focal, subacute, viral retinitis.

To study local intravitreal therapies for retinitis due to herpes viruses, an animal model of focal, subacute, relatively nonlethal herpes family retinitis is needed. Herpes simplex virus type 1 (HSV-1) was injected into the subretinal space of 33 Dutch pigmented rabbit eyes. The animals were observed for up to 42 days after the inoculation. All inoculated eyes developed a focal, enlarging area of retinitis in a predictable manner, showing focal enlarging areas of retinal opacification and necrosis with variable retinal hemorrhage. In the inoculated eyes, retinal detachment developed in all animals within 21 days; 33% of the animals developed focal retinitis in the uninoculated eye. Histologic examination showed encephalitis to be present in 11 (73%) of the 15 animals studied after 1 week. This model may be used to evaluate the therapeutic efficacy of new antiviral agents and modalities in the treatment of herpes family viral retinitis. The model is most similar to herpes simplex or zoster retinitis in humans, but also shares some similarities (and differences) with cytomegalovirus (CMV) retinitis in humans.

Experimental infection of the conjunctival sac of lambs with Mycoplasma conjunctivae

Ovine keratoconjunctivitis (OKC) identical to that seen in field cases was produced experimentally with 10(6) colony forming units of an isolate of Mycoplasma conjunctivae which had been passaged three times in vitro. Cytological studies showed that the peak neutrophil count in conjunctival exudate occurred 8 days after inoculation of the conjunctival sac. Rapid onset of clinical signs in the uninoculated eye showed the ease with which the organism could be transferred from affected to unaffected eyes.

Protection from retinal necrosis by passive transfer of monoclonal antibody specific for herpes simplex virus glycoprotein D.

Passive administration of antibody against herpes simplex virus type 1 (HSV-1) has been shown to protect against stromal keratitis and death from encephalitis. Although the exact mechanism by which passively-transferred antibody protects is not known, one of the features of protection by passively-transferred antibody is interference with the ability of the virus to spread within the nervous system. In the experiments reported herein, studies were performed to determine if 8D2, a monoclonal antibody against a type-common epitope of glycoprotein D, could protect mice from retinal necrosis following uniocular anterior chamber inoculation of HSV-1. Mice were protected from retinal necrosis when the antibody was administered 2 hours before virus inoculation or 24 hours after virus inoculation. When antibody was injected 2 hours before virus inoculation, the titer of virus at day 1 p.i. in the injected eyes of antibody-treated and control mice was the same, but by 3 days p.i., the titer of virus in the antibody-treated mice was significantly lower than that recovered from control mice. The titers of virus in the brains and in the uninoculated eyes of antibody-treated mice were also significantly lower than in control mice. The results of these studies suggest that passively-transferred antibody protects against retinal necrosis by limiting spread of virus to the CNS or replication of virus within the CNS.

Mechanisms of protection against herpes simplex virus type 1-induced retinal necrosis by in vitro-activated T lymphocytes

In BALB/c mice, acute retinal necrosis occurs in the uninoculated eye 8 to 10 days following uniocular anterior chamber inoculation of the KOS strain of herpes simplex virus type 1 (HSV-1). Retinitis in the uninjected eye can be prevented if HSV-1-specific immune effector cells that have been restimulated with virus in vitro are administered intravenously within 1 day of anterior chamber inoculation of virus. We explored further the mechanism of protection afforded by these activated immune effector cells. The results of our studies revealed that optimal protection from retinitis required in vitro restimulation, since infusion of 50 x 10(6) HSV-1-primed but nonrestimulated cells could not protect as well as 10 x 10(6) activated cells. Analysis of both restimulated and nonrestimulated cells showed that only in vitro-restimulated cells were cytotoxic to HSV-1-infected syngeneic target cells. From these studies, we concluded that the ability to kill virus-infected target cells contributed to optimal protection achieved by intravenous administration of activated immune effector cells. Furthermore, T-cell subset depletion of activated immune effector cells demonstrated that both L3T4+ and Lyt-2+ T cells in the transfer inoculum contributed to protection. Additional studies revealed that although the transferred immune effector cells reached the injected eye within 24 h, virus replication in the injected eye was not affected. In the uninjected eye, virus titers were low, consistent with protection of this eye from retinitis. Taken together, the virus recovery results suggest that the interaction of virus with intravenously administered HSV-1-specific immune effector cells which limits virus spread and/or replication of virus probably occurred within the central nervous system and prevented the second wave of virus from entering the uninoculated eye.

ACAID requires early replication of HSV-1 in the injected eye.

After uniocular anterior chamber inoculation of the KOS strain of HSV-1 in BALB/c mice, acute retinal necrosis develops in the uninoculated eye. These mice exhibit suppression of virus-specific delayed hypersensitivity which is the hallmark of anterior chamber associated immune deviation (ACAID). In contrast, inoculation of C57BL/6 mice with KOS induces vigorous virus-specific DTH, and there is no retinal necrosis in the uninoculated eye. We performed experiments using RH116, a mutant of KOS and SC16, a neurovirulent strain of HSV-1, in BALB/c and C57BL/6 mice to examine whether virus or host factors determine the outcome of anterior chamber inoculation of HSV-1 (ACAID or DTH, retinal necrosis or retinal preservation). We found that high titers of virus (approximately 10(5)) within the first 24 hours in the inoculated eye were linked to the induction of ACAID and that the induction of ACAID following anterior chamber inoculation of HSV-1 is neither an exclusive feature of a strain of virus nor is the ability to develop ACAID a distinguishing characteristic of an individual strain of mice. Taken together, our findings suggest that the interplay of both virus and host factors results ultimately in acute retinal necrosis following anterior chamber inoculation of HSV-1 in the mouse.

Schisis contributes to necrosis in experimental HSV-1 retinitis

Injection of the KOS strain of herpes simplex virus type 1 into the anterior chamber of one eye of a BALB c mouse produces bilateral retinal inflammation which progresses in the contralateral eye to total retinal necrosis by day 10 post-inoculation. Although both immune and direct viral cytopathic effects have been proposed as causes of the initial infiltration, the precise mechanism(s) of the contralateral retinal necrosis remains uncertain. In this study, histopathological examination of the uninoculated eyes of HSV-1 injected BALB c mice revealed the presence of vitreous traction against the internal limiting membrane of the retina which was associated with separation of the nerve fiber layer from the underlying ganglion cell layer. This separation resulted in avulsion of Mueller cell footplates and retinal vessels, hemorrhage into the schisis cavity and disruption of the underlying retinal architecture. The schisis began focally on day 8 or 9 post-inoculation, and the entire retina of most animals was involved by day 10 or 11. These results suggest that retinal schisis involving separation of the nerve fiber layer from the ganglion cell layer contributes to necrosis of the retina in the uninoculated contralateral eye.

Histopathologic study of herpes virus-induced retinitis in athymic BALB/c mice: Evidence for an immunopathogenic process

In order to determine whether antiviral immunity is pathogenic in mouse eyes, HSV-1 was injected into the anterior chamber of one eye of adult athymic BALB/c mice. The eyes of these T cell deficient mice were examined clinically and histopathologically for ocular disease. The anterior segment of injected eyes developed progressive inflammatory reactions that eventually destroyed the ciliary body and then progressed to the posterior compartment where partial necrosis occurred, but only in the inner layers of the retina. A milder form of the same process developed between 7 and 10 days in the contralateral eye. Uninoculated eyes displayed little evidence of choroiditis, hemorrhage, massive necrosis, or disintegration of the architecture of the retina. Since these are features that are found in contralateral retinas of euthymic BALB/c mice infected in one eye via the anterior chamber route, it is concluded that acute retinitis found in contralateral eyes of immunocompetent mice has an immunopathogenic basis. However since euthymic mice develop anterior chamber associated immune deviation (ACAID) (and therefore do not display virus-specific delayed hypersensitivity), the identity of the relevant immune effector remains unknown. Based on these observations and our previous ocular findings following intracameral inoculation of HSV-2, we suggest that in susceptible mice, herpes simplex viruses can induce several pathogenetically distinct forms of retinitis, some of which are mediated by virus-specific immune effector cells.

Spread of herpes simplex virus within ocular nerves of the mouse: demonstration of viral antigen in whole mounts of eye tissue.

Spread of herpes simplex virus to and within the mouse eye after inoculation of the cornea or the skin of the snout was examined by peroxidase-antiperoxidase (PAP) staining of viral antigen in flat mounts of the eye and by isolation of virus from nervous tissue. Following inoculation of virus at either site, viral antigen was found in ocular nerves. One to three days later antigen was also found in the iris, ciliary body and choroid/sclera suggesting that virus spread to these tissues occurred via their nerve supply. Viral antigen was also found in the retina of the uninoculated eye after corneal inoculation. After inoculation of the snout, virus was isolated from ophthalmic and maxillary parts of the trigeminal ganglion and the superior cervical ganglion and then from the brainstem, eye and mandibular part of the trigeminal ganglion. This sequence also suggested that virus reached the eye via the nerves and that this may occur indirectly via the brainstem. The PAP method allows rapid determination of the distribution of antigen in various tissues. Our observations suggest that widespread involvement of ocular tissue may occur by spread of virus in nerves within the eye.

Quantitative studies on langerhans cells in mouse corneal epithelium following infection with herpes simplex virus

Dendritic Langerhans cells (LCs) were identified in flat-mount preparations of mouse corneal epithelium after staining for ATPase activity. They were found predominantly in the limbus, but after inoculating the cornea with HSV1 strain SC16 LC, numbers increased both in the limbus and the central cornea. Numbers of LCs reached a maximum on day 8 and if severe keratitis was present remained high at least until day 22. A small but significant increase in LCs was also found in the opposite, uninoculated eye in mice with severe damage in the inoculated eye. After HSV inoculation on the snout, 60% of mice had corneal disease in the eye on the inoculated side; in such mice corneal LCs were at a maximum 18 days after inoculation. The increase in LC numbers was similar whether inoculation was into the cornea or in the snout. After corneal inoculation the cells were distributed fairly evenly over the corneal surface, with accumulations limited to epithelial ulcers. However, after inoculation on the snout, numerous clusters were seen over the epithelial surface, often surround by epithelium devoid of LCs.

Virus-specific DTH prevents contralateral retinitis following intracameral inoculation of HSV-2.

Following inoculation of HSV-1 (KOS strain) into the anterior chamber of one eye of a BALB/c mouse, the virus travels to the uninoculated contralateral eye and contributes to the devastating retinal necrosis which occurs in this eye 10-12 days p.i. In parallel experiments, HSV-2 (MS strain) was inoculated uniocularly via the anterior chamber route; animals were sacrificed at intervals and their eyes removed for histopathology and virus culture. Histopathological examination revealed that, in contrast to the retinal destruction observed in HSV-1 inoculated animals, the retina of the contralateral eye of HSV-2 injected animals was unaffected. Culture studies demonstrated that, similar to the spread of HSV-1 after anterior chamber inoculation, HSV-2 reached the contralateral eye in two temporally separate waves and also revealed that the amount of virus recovered from the uninoculated eye of HSV-2 infected animals was significantly less than that recovered from the uninoculated contralateral eye of HSV-1 injected mice. Further examination demonstrated that animals inoculated with HSV-2 via the anterior chamber route did not develop the suppression of virus-specific delayed hypersensitivity (DH) which is characteristic of HSV-1 induced anterior chamber associated immune deviation (ACAID). Taken together, the sparing of the contralateral retina and the ability to generate a virus-specific DH response suggest that DH assists in the preservation of the contralateral retina of animals inoculated with HSV-2 via the anterior chamber route by limiting virus replication and the amount of virus which reaches the uninoculated eye.