Passive transfer of anti-HSV-1 IgG protects against stromal keratitis in mice

Discovery of potential diagnostic and vaccine antigens in herpes simplex virus 1 and 2 by proteome-wide antibody profiling

Routine serodiagnosis of herpes simplex virus (HSV) infections is currently performed using recombinant glycoprotein G (gG) antigens from herpes simplex virus 1 (HSV-1) and HSV-2. This is a single-antigen test and has only one diagnostic application. Relatively little is known about HSV antigenicity at the proteome-wide level, and the full potential of mining the antibody repertoire to identify antigens with other useful diagnostic properties and candidate vaccine antigens is yet to be realized. To this end we produced HSV-1 and -2 proteome microarrays in Escherichia coli and probed them against a panel of sera from patients serotyped using commercial gG-1 and gG-2 (gGs for HSV-1 and -2, respectively) enzyme-linked immunosorbent assays. We identified many reactive antigens in both HSV-1 and -2, some of which were type specific (i.e., recognized by HSV-1- or HSV-2-positive donors only) and others of which were nonspecific or cross-reactive (i.e., recognized by both HSV-1- and HSV-2-positive donors). Both membrane and nonmembrane virion proteins were antigenic, although type-specific antigens were enriched for membrane proteins, despite being expressed in E. coli.

Kinetics of immune cell infiltration in vaccinia virus keratitis

PURPOSE

Vaccinia virus keratitis leading to blindness is a severe complication of smallpox vaccination. The clinical manifestations of vaccinia virus keratitis are similar to those of herpes simplex virus keratitis, a well-studied immunopathologic disease. Vaccinia virus keratitis is likely to involve an immunopathologic component, but little is known about the pathogenesis of the disease. The goal of this study was to determine type and kinetics of immune cell infiltration in the cornea during vaccinia virus keratitis.

METHODS

Rabbit eyes were trephined and inoculated with 1x10(5) pfu of the Dryvax strain of the vaccinia virus. On days 2, 4, 7, 10, 14, and 28 after infection, the animals were scored for clinical disease and eye sections were stained for B cells, CD4+ cells, CD8+ cells, and neutrophils. The eyelid, ciliary body, cornea, iris, iridocorneal angle, and choroid were examined.

RESULTS

Corneal vaccinia virus challenge resulted in the infiltration of B cells, CD4+ cells, CD8+ cells, and neutrophils into the cornea and eyelids. Neutrophils were the predominant cell type on days 2 and 3 after infection, whereas CD4+ cells were the predominant cell type detected in corneas on days 4 through 10. CD8+ cells and B cells peaked on day 10, but at lower levels than CD4+ cells and neutrophils.

CONCLUSIONS

These results suggest that sequential migration of neutrophils, then CD4+ cells, plays an important role in vaccinia virus keratitis.

Molecular mimicry by herpes simplex virus-type 1: autoimmune disease after viral infection

Viral infection is sometimes associated with the initiation or exacerbation of autoimmune disease, although the underlying mechanisms remain unclear. One proposed mechanism is that viral determinants that mimic host antigens trigger self-reactive T cell clones to destroy host tissue. An epitope expressed by a coat protein of herpes simplex virus-type 1 (HSV-1) KOS strain has now been shown to be recognized by autoreactive T cells that target corneal antigens in a murine model of autoimmune herpes stromal keratitis. Mutant HSV-1 viruses that lacked this epitope did not induce autoimmune disease. Thus, expression of molecular mimics can influence the development of autoimmune disease after viral infection.

Immunity causing blindness: five different paths to herpes stromal keratitis

Herpes stromal keratitis (HSK) is a blinding infectious disease that results from an array of immunopathogenic processes, including herpes simplex virus 1 (HSV-1)-specific T helper 1 (Th1) and Th2 cells, cytotoxic T cells and antibodies. As discussed here by Wayne Streilein and colleagues, strategies designed to prevent and treat this syndrome must be aware of the fact that the disease is multifactorial in its cause and pathogenesis.

Tetrandrine potently inhibits herpes simplex virus type-1-induced keratitis in BALB/c mice

This study investigated the effect of tetrandrine (TDR) on experimental herpes simplex keratitis (HSK) in mice. BALB/c mice were divided as follows: Group 1, untreated; Group 2, acyclovir (ACV)-treated from day 0 postinfection; Group 3, ACV-treated from day 7; Group 4, TDR-treated from day 0; and Group 5, TDR-treated from day 7. All mice were infected in the right cornea with herpes simplex virus (HSV) type I. TDR 30 mg/kg and ACV 120 mg/kg were administered intraperitoneally daily. The mice were observed for 14 days postinfection. Clinical inflammatory reactions and ocular histopathology were analyzed. The herpes specific antibody response and the delayed type hypersensitivity (DTH) response were studied. Of the 22 untreated mice, 16 developed HSK (incidence, 72.7%). TDR given from day 7 reduced the HSK incidence to 8.5% (p < 0.01); the incidence of HSK was 45.4% in mice treated with TDR from day 0 (p > 0.05). Systemic ACV given from day 0 inhibited HSK development (p < 0.01); ACV given from day 7 resulted in an HSK incidence of 50% (p > 0.05). The specific anti-HSV antibody response in the serum of mice treated with TDR or ACV either from day 0 or day 7 was significantly less than that of untreated mice (p < 0.01 and p < 0.05, respectively), and TDR treatment suppressed DTH responses to HSV (p < 0.05). Systemic TDR administered after HSV inoculation of the cornea significantly modulates murine HSK development at least partly by modifying the host immune/inflammatory response to the virus.

The importance of MHC-I and MHC-II responses in vaccine efficacy against lethal herpes simplex virus type 1 challenge

To investigate the importance of major histocompatability complex (MHC) class I- and MHC class II-dependent immune responses in herpes simplex virus-1 (HSV-1) vaccine efficacy, groups of beta 2% (MHC I-) and Ab% (MHC II-) mice were inoculated with various vaccines, and then challenged intraperitoneally with HSV-1. Following vaccination with either live avirulent HSV-1, expressed HSV-1 glycoprotein D (gD), or a mixture of seven expressed HSV-1 glycoproteins (7gPs), Ab% (MHC-II-) mice developed no enzyme-linked immunosorbent assay (ELISA) or neutralizing antibody titres. In contrast, significant ELISA and neutralizing antibody titres were induced in beta 2m% (MHC-I-) mice by all three vaccines. The neutralizing antibody titres were similar for all three vaccines, but were only approximately 1/4 to 1/3 of that developed in C57BL/6 (parental) mice vaccinated with the same antigens. All three vaccines protected 100% of the wild-type C57BL/6 mice against lethal challenge with 2 x 10(7) plaque-forming units (PFU) of HSV-1. The live virus vaccine and the 7gPs vaccine also protected 80% of the beta 2m% mice against the same lethal HSV-1 challenge dose. In contrast, in Abo/o mice, none of the vaccines provided significant protection against the same lethal challenge dose of HSV-1. However, at a lower challenge dose of 2 x 10(6) PFU, all three vaccines protected 70-80% of the vaccinated Ab% mice (compared to only 10% survival in mock vaccinated controls). Thus, vaccination provided some protection against lethal HSV-1 challenge in both beta 2m% and Ab% mice; however, the protection was less than that seen in the parental C57BL/6 mice. In addition, Ab% mice were less well protected by vaccination than were beta 2m% mice. Our results suggest that (1) both MHC-I and MHC-II are involved in vaccine efficacy against HSV-1 challenge; (2) both types of responses must be present for maximum vaccine efficacy: and (3) the MHC-II-dependent immune response appeared to be more important than the MHC-I-dependent immune response for vaccine efficacy against HSV-I challenge.

The role of B lymphocytes in experimental herpes simplex viral retinitis

The purpose of this study was to examine B cell participation in experimental herpes simplex virus (HSV) retinitis. Passive immunization with anti-herpes antibody protects BALB/c mice from herpes simplex retinitis (HSR). Using anti-Mu antibody treatment, we modified the B cell population of C.B-17 mice, normally resistant to HSR, in order to test the hypothesis that such treatment would render them susceptible to HSR by impairing their early antibody response to anterior chamber (AC) inoculation with HSV. We analysed the effect of anti-Mu treatment on their susceptibility to HSR and then employed Polymerase Chain Reaction (PCR) and ELISA techniques to study the patterns of immunoglobulin gene and protein expression, and the T-cell receptor alpha/beta (TCR alpha/beta) gene expression after AC inoculation of HSV. Immunohistopathologic analysis revealed that 100% of the B cell deficient mice (B-) developed contralateral retinitis following AC inoculation, confirming the hypothesis that anti-Mu antibody treatment would convert HSR-resistant mice into HSR-susceptible ones. Transfer of B cells from naive congenic donor mice resulted in 67% of recipient B- mice developing contralateral retinitis. Transfer of anti-HSV antibody conferred nearly complete protection, with only 11% of mice developing retinitis (P < 0.005). PCR and ELISA analysis showed that both untreated and B- C.B-17 mice showed similar dynamic patterns of mRNA IgG isotype expression and of anti-HSV IgG isotypic antibody response following AC inoculation. Thus, we were forced to reject the hypothesis that an impaired early antibody response is primarily responsible for the increased HSR susceptibility seen in B- mice. In contrast, PCR analysis of TCR alpha/beta mRNA expression revealed dramatic differences between susceptible and resistant mice, suggesting that TCR V beta selection and usage may be a critical factor influencing HSR-sensitivity in this murine model, and that B cells (and immunoglobulin isotype) may play a role in TCR V beta selection and usage after ocular encounter with HSV.

The role of natural killer cells in the development of herpes simplex virus type 1 induced stromal keratitis in mice

Natural killer (NK) cells and acquired cell-mediated immunity effector cells (delayed type hypersensitivity (DTH) and cytotoxic T lymphocytes (CTL)) have been reported to play a vital role in the defence of the host against tumour and viral infections in locations other than the eye. A vigorous cellular inflammatory response to viral infections of the cornea, however, with the attendant damage to the corneal clarity, has obvious evolutionary disadvantages, and a substantial body of evidence indicates that in animals (e.g. mice) which are highly susceptible to inflammatory destruction of the cornea following corneal encounter with herpes simplex virus, it is the animal's immunological/inflammatory response which is responsible for the corneal damage. We examined the role of natural killer cells in the development of herpes stromal keratitis (HSK) in NK-deficient (C57BL/6J-bgj (beige)) mice and their NK-competent (C57BL/6J (black) relatives. The beige (NK-deficient) mice were just as resistant to HSK as were the black mice. We also studied the effects of NK cell depletion of BALB/c Igh-1 disparate congenic mice. C.AL-20 (Igh-1d) mice are ordinarily highly susceptible to necrotising HSK. In vivo NK-cell depletion in these mice significantly decreased the incidence and severity of HSK in these animals (p < 0.0005). Corneas from untreated C.AL-20 mice contained T cells, macrophages and NK cells. The corneal infiltrate from NK-depleted C.AL-20 mice consisted of T cells and macrophages but no NK cells. These data indicate that NK cells are participants in the development of HSK in the murine model of this disease.

The role of Igh-1 disparate congenic mouse T lymphocytes in the pathogenesis of herpetic stromal keratitis

The corneal destruction associated with herpes simplex keratitis (HSK) is primarily the result of the host's immune response to herpes simplex virus type-1 (HSV-1) infection. We examined the role of T cells and T cell subsets in the pathogenesis of HSK. Naive and immune T cells and HSV-1 immune CD4+ and CD8+ subsets from Igh-1 disparate BALB/c congenic mice were adoptively transferred into athymic BALB/c nude mice, which normally do not develop HSK. The results demonstrated that while the transfer of naive T cells from either HSK-susceptible C.AL-20 (Igh-1d) or HSK-resistant C.B-17 (Igh-1b) mice had little influence on HSK development, transfer of either CD3+ or CD4+ HSV-1 immune T cells from C.AL-20 mice resulted in the development of severe HSK in all of the recipients. Transfer of the same cell populations from C.B-17 mice resulted in the development of only a mild keratitis in 50% of the recipients. Transfer of CD8+ cells from either donor strain did not result in stromal disease in any recipient mouse. These results clearly demonstrate the pivotal role of CD4+ T cells in the development of necrotizing herpes stromal keratitis, and further demonstrate that CD8+ T cells are not essential in HSK development in the BALB/c system.

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.

Herpes simplex keratitis: role of viral infection versus immune response

The cumulative clinical and experimental data regarding the role of viral infection versus the immune response in the pathogenesis of herpes simplex stromal keratitis and central disciform endotheliitis are discussed. Ultrastructural and viral isolation studies have been performed in only a limited number of cases of human stromal keratitis and disciform endotheliitis. Virus has been isolated from the minority of corneas cultured, whereas viral particles have been demonstrated in selected cases of stromal keratitis, most of which had been treated with steroids at some point in time. The possibility of corneal latency in cases of quiescent herpetic stromal keratitis will require further systematic study. Review of the experimental and clinical findings suggests a dialectical role of the immune response in limiting viral infection, while contributing to corneal opacification and scar formation.

External ocular herpesvirus infections in immunodeficiency

Infections of the eye with members of the herpes family of viruses (e.g. HSV, CMV, VZV) are frequent manifestations of acquired and inherited defects in cell mediated immunity. Herpesvirus infections in the immunocompromised may reflect frequent viral reactivation from the latent state, as well as extensive productive infection of ocular structures following reactivation or primary infection. A review of experimental and clinical studies of both acquired and inherited immune dysfunction implicates specific immune mechanisms influencing the establishment of latency, viral reactivation and the control of active viral replication in ocular tissues.

An improved model of recurrent herpetic eye disease in mice

Mice were passively immunized with serum containing antibodies to herpes simplex virus type 1 (HSV-1) before inoculation on the cornea with HSV-1 strain McKrae. After such immunization most mice survived and most had normal eyes. When primary infection had subsided, mice with normal eyes were selected and treated with cyclophosphamide, dexamethasone and UV irradiation of the inoculated eye or UV irradiation alone, to reactivate latent virus. After either treatment mice developed signs of recurrent infection (virus in eyewashings and recurrent corneal and/or lid disease). The incidence of such signs was 17/33 (52%) in mice receiving immunosuppressive drugs and UV irradiation and 19/32 (59%) in mice given UV irradiation alone. In mice treated with either stimulus dendritic or geographic ulceration of the cornea was seen. These closely resembled the herpetic lesions seen in humans. There was good correlation between the pattern and distribution of recurrent corneal disease and the distribution of cells containing virus antigens in corneal epithelial sheets. Again, as in humans, the induction of recurrent infection was found to correlate poorly with a rise in the level of serum neutralizing antibody. In mice treated with UV irradiation alone corneal ulcers healed and the eyes returned to normal. By contrast, in mice given immunosuppressive drugs and UV irradiation, the ulceration became more severe and the eyes became opaque and vascularized. The use of passive immunization has greatly improved our previously reported model of recurrent herpetic eye disease since it has increased the incidence of mice suitable for the induction of recurrent infection and has increased the incidence of such infection.