Induction of Fc and C3b receptors on rabbit corneal cells by herpes simplex virus

The expression of receptors for Fc portion (FcR) of immunoglobulin G (IgG) and for a C3b component of complement (C3bR) by herpes simplex virus (HSV) was studied in primary cultures of rabbit corneal cells. Monolayer cultures of epithelial, stromal and endothelial cells of the rabbit cornea were infected with three strains each of type 1 (HSV-1) and type 2 HSV (HSV-2). Rosette methods were used to detect receptors by means of sheep erythrocytes sensitized with rabbit IgG for FcR and C3b-coated sheep erythrocytes for C3bR. The FcR were expressed regularly on epithelial, stromal and endothelial cells by all three strains of both HSV-1 and HSV-2. The C3bR, however, were expressed only by HSV-1 on epithelial and stromal cells. Little or no C3bR activities could be detected on endothelial cells infected with any strain of HSV-1 or HSV-2. The FcR and C3bR expressed on corneal cells were induced by HSV and were blocked by monoclonal antibody to HSV-1 glycoprotein E(gE) or glycoprotein C(gC) respectively, confirming findings of other investigators that gE acts as FcR and gC as C3bR.

Stress proteins accumulate in cultured retinal glial cells during herpes simplex viral infection

The production of stress- or heat-shock proteins (SP) which are defined by three monoclonal antibodies (TI56, TG5E and TG7A) were examined in cultured retinal glial cells with and without herpes simplex virus (HSV) infection. Indirect immunofluorescence showed that 80-90% of uninfected cells reacted with anti-glial fibrillary acidic protein (GFAP) and that 10-20% of uninfected cells were weakly labelled with anti-SP antibodies. By 6 hr after HSV infection, the proportion of GFAP labelled cells decreased to 60-70% whereas cells strongly expressing SP antigens were demonstrated. At 24 hr, GFAP+ cells were markedly reduced in number and immunolabelling with anti-SP antibodies was evident in approximately 50% of cells, directly demonstrating the accumulation of SP in cultured retinal cells after HSV infection. Double labelling with GFAP/TI56 indicated that 30% of GFAP+ cells were labelled with TI56 and 30-50% of TI56+ cells were also GFAP+, despite the abrupt loss of GFAP+ cells during HSV infection. These results indicate that SP normally expressed at low level are significantly upregulated in retinal glial cells following HSV infection.

Analysis of glycoproteins expressed by isolates of herpes simplex virus causing different forms of keratitis in man

An in vitro analysis of glycoprotein produced by nine human ocular isolates of HSV-1 is reported. The source of the isolates was; three patients with recurrent dendritic keratitis, three with chronic stromal disease and three with primary keratoconjunctivitis. Virus strains were labelled with the radioactive precursors (35S) methionine and (14C) glucosamine. Radiolabelled viral glycoproteins were subsequently analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), followed by autoradiography. Viral glycoproteins were further characterised by immuno-precipitation with polyclonal and monoclonal antibodies to HSV. The stromal isolates excrete larger amounts of 'soluble' precursor glycoprotein D than those in the other two disease categories. It is possible that the immune response to glycoprotein D is in part responsible for the severity of stromal disease.

Reevaluation of human alpha interferons against herpesvirus infection of the rabbit eye

Because of reported differences in potency, recombinant DNA-derived human alpha interferons (IFNs) were reevaluated for use against acute Herpes Simplex Virus type 1 (HSV-1) infection of the rabbit eye. The IFNs used topically were IFN-alpha 2, (IFN-alpha 2) and a consensus of known human IFN-alpha s, designated IFN-alpha Con1. Prophylactic treatment with IFN-alpha Con1 at 1 or 15 X 10(6) U/eye/day beginning 48 hours before HSV-1 inoculation and therapeutic treatment with 5 or 15 X 10(6) U/eye/day beginning 4 hours after inoculation with either IFN-alpha Con1 or IFN-alpha 2 appeared to prevent or significantly reduce the development of corneal epithelial involvement. The effects were dose dependent with no evidence for decreased activity at the higher dose. The duration of HSV-1 shedding into tear film was not significantly reduced.

Effect of neuraminidase on Fc and C3b receptors on rabbit corneal cells infected with herpes simplex virus

The effect of neuraminidase on Fc receptors (FcR) and C3b receptors (C3bR) was studied in epithelial, stromal and endothelial cells of the rabbit cornea infected with type 1 (HSV-1) and type 2 herpes simplex virus (HSV-2) in vitro. FcR were induced on epithelial, stromal and endothelial cells of the rabbit cornea by both HSV-1 and HSV-2, but their activities were not enhanced by neuraminidase. On the other hand, the treatment of HSV-infected corneal cells with neuraminidase resulted in the enhancement of C3bR activities on epithelial, stromal and endothelial cells infected with HSV-1, and the enhancing effect of neuraminidase was more pronounced on corneal endothelial cells. A similar neuraminidase treatment had no significant effect on C3bR activities on the corneal cells infected with HSV-2.

Interferon production in inbred mice during herpetic eye disease

Low levels (less than 5 units/eye) of interferon (IFN) were detected in the eyes of BALB/c and C57BL/6 mice one to five days after instillation of 10(7) pfu/eye of herpes simplex virus type 1 (HSV) onto scarified corneas. This dose of virus produced herpetic keratitis characterized by dendritic epithelial lesions one day post infection in both strains of mice. The disease progressed to severe necrotizing stromal keratitis in the eyes of all BALB/c mice, but only three of 10 eyes of C57BL/6 mice by 21 days after infection. Footpad immunization 30 days prior to ocular infection protected both strains from stromal disease, but did not enhance IFN production in the eye. At lower inoculating doses of virus (less than or equal to 10(5) pfu/eye), C57BL/6 mice showed greater resistance to stromal disease and produced less virus over a shorter period of time than BALB/c mice. No IFN was detected at any time after infection with doses of virus less than 10(7) pfu/eye, nor was IFN detected in plasma of any infected mice. The failure to detect high levels of IFN in homogenates of eyes did not reflect an inability of ocular tissues to produce IFN since IFN-beta was detected as early as two hours after topical treatment with the potent IFN inducer, carboxymethylacridanone (CMA). The two mouse strains produced similar levels of IFN in the eye in response to CMA. These data indicated that the relative resistance of mice to HSV eye infection was not related to the rapid local production of IFN, nor was resistance related to systemic IFN production in plasma or spleen.

Arachidonic acid metabolism to eicosanoids in herpes virus-infected rabbit cornea

The metabolism of the polyunsaturated fatty acid, arachidonic acid (20:4, n-6) in rabbit cornea with varying severities of herpes simplex viral infection was investigated. The results indicate an active synthesis of the lipoxygenase and cyclooxygenase reaction products of arachidonic acid in central cornea and corneal-scleral rim. Stimulation of 12-hydroxyeicosatetraenoic acid (12-HETE) production in herpes-infected cornea was correlated positively with the severity of infection. Other eicosanoids were increased maximally in moderately infected corneas. The stimulation of eicosanoid synthesis was more evident in central cornea as compared to corneal-scleral rim. Herpes infection also caused a decline in the incorporation of radiolabeled arachidonic acid into membrane glycerolipids. These data indicate that the production of eicosanoids from arachidonic acid is stimulated in herpes-infected cornea. The stimulation may reflect the presence of phagocytic cells in the infected cornea, an enhanced capacity of the cornea itself to produce eicosanoids, or a combination of these effects. Decreased acylation of membrane lipids may be the result of infection-induced activation of fatty acid release mechanisms, which would lead to degradation of cell membranes. The presence of lipoxygenase reaction products in the herpes-infected cornea introduces a new factor for consideration in the design of therapeutic regimens for this disease.

Therapy with 9-beta-D-arabinofuranosyladenine (ARA-A) and 2'-deoxycoformycin increases the ARA-A content of ocular tissues

The amount of 9-beta-D-arabinofuranosyladenine (ARA-A) and 9-beta-D-arabinofuranosylhypoxanthine (ARA-Hx) present in ocular tissues of rabbits was determined following therapy with ARA-A alone and when ARA-A was used in combination with 2'-deoxycoformycin (dCF). Topical therapy was initiated three days after infection of the corneas of rabbits with herpes simplex virus type 1. Ocular tissues were harvested after two days of therapy and analyzed by high performance liquid chromatography. Combination topical therapy with ARA-A and dCF significantly increased the tissue content of ARA-A in all tissues examined except retina, as compared to therapy with ARA-A alone. The ARA-A content of the two ocular tissues most often subject to acute herpes infections, the conjunctiva and cornea, was increased from 29.9 +/- 11.7 to 144.0 +/- 53.3 pmoles/mg dry weight and from 15.4 +/- 6.1 to 231.8 +/- 30.8 pmoles/mg dry weight, respectively. Except for the aqueous humor, the total arabinoside content of each tissue was not significantly altered by combination therapy, merely the ratio of ARA-A to ARA-Hx was changed. These studies demonstrate that combination topical therapy with ARA-A and an inhibitor of ARA-A catabolism, dCF, can effectively result in elevated amounts of ARA-A in ocular tissues.

Penetration of 14C-methisoprinol into rabbit eyes with experimentally induced herpetic keratitis

The authors studied the penetration of 14C-labelled methisoprinol into ocular tissues (cornea, aqueous humour and iris) in rabbits, in which herpetic keratitis had been experimentally induced. It has been demonstrated that the methisoprinol crosses the corneal barrier. The maximum concentration of the drug in the tissues examined was measured 30 min after the instillation of the drug into the conjunctival sac, and persisted for 60 min, although at a slightly lower level.

Recombinant human interferon alpha D in HSV-1 recurrence in the rabbit

Recombinant human interferon alpha subtype D (RIFN alpha D) was effective in reducing the shedding of herpes simplex virus type-1 (HSV-1) induced by 6-hydroxydopamine iontophoresis followed by topical epinephrine application in previously infected rabbit corneas. A treatment schedule of RIFN alpha D, two drops QID was superior to one drop BID. RIFN alpha A also appeared to be effective in reducing viral shedding. Rabbits treated with RIFN alpha D during two episodes of adrenergically induced HSV-1 shedding, but not during anticipated episodes of spontaneous shedding, did not show a significant reduction in shedding of virus. Interferon was present in significantly higher concentration in tear samples following treatment with RIFN alpha D as compared with RIFN alpha A.

Analysis of viral DNA in isolates from patients with recurrent herpetic keratitis

Isolates were obtained from 10 patients with recurrent herpes simplex type 1 infection of the eye, lids, or mouth. The viral DNA of successive isolates from each patients was analyzed by restriction endonuclease fingerprinting. Evaluation of the DNA banding patterns of all isolates by means of two different enzymes, performed in a masked fashion, demonstrated that all of the isolates from any one patient had the same genetic makeup. These results indicate that recurrent herpes infections of the eye and face in humans are caused not by unrelated, serial infections but rather by reactivation of the same latent virus that remains in the ganglion over a period of years.

Schirmer test values and lysozyme content of tears in acute dendritic keratitis

In acute dendritic keratitis, the lacrimal flow is increased in the affected eye but not in the normal fellow eye. After recovery the tearflow returns to normal. The lysozyme concentration in the affected and the normal fellow eye do not differ statistically significantly nor do they differ significantly from values of an age- and sex-matched control group. There is no correlation between tearflow and lysozyme concentration. These findings support the view of a constant composition of stimulated tear fluid, irrespective of tear volume produced.

Corneal sensitivity and substance P in experimental herpes simplex keratitis in mice

Experimental herpes simplex keratitis in the mouse produced a rapid fall in both corneal sensitivity and levels of corneal substance P (SP). This finding supports the association of SP with sensory neurones and shows that such levels can be used as an indication of damage to neurones resulting, for example, from infection with HSV. However, the delay in recovery of SP compared to the more rapid and complete recovery of sensitivity suggests that SP in the cornea is not directly involved in mediation of the blink reflex.

Lipofuscin in rabbit skin: Its occurrence after ocular herpes simplex infection

Systemic infection, induced by intraocular inoculation of type 1 herpes simplex virus (HSV 1) in young rabbits, is accompanied by the appearance of autofluorescent pigments precisely in the midportion of their fur follicles. Histochemical and solubility reactions of the pigment led to its characterization as a lipofuscinlike pigment. Follicle fluorescence correlated with the severity of clinical symptoms; it was present in 100% of the follicles of rabbits that died but was found in only 30% to 50% of follicles of surviving animals. Similar fluorescence was also present in 10% to 20% of the follicles of uninfected rabbits. This autofluorescent material may be formed by the peroxidation of lipids from sebaceous gland secretions, but neither HSV 1 nor antigens could be found in the skin as possible initiators of this reaction.

Characterization of a glucocorticoid receptor and the direct effect of dexamethasone on herpes simplex virus infection of rabbit corneal cells in culture

Homogenates prepared from a previously established cell line derived from rabbit cornea contain a macromolecule with many properties of a glucocorticoid receptor, namely high affinity (KD = 6 x 10(-9)M) and saturable capacity (135 femtomoles/mg protein) for dexamethasone, extreme heat lability, and a pattern of competition similar to that found in other glucocorticoid target cells. Intact cells specifically bind dexamethasone with an affinity similar to that found in homogenates, and the amount of steroid bound at saturation is approximately 60,000 molecules of dexamethasone per cell. Specific dexamethasone binding was found to be localized to the cell nucleus. The corneal cells were susceptible to infection with herpes simplex virus (HSV). Dexamethasone increased cell susceptibility to the virus and facilitated the spread of the infection throughout the corneal cell culture. This effect was observed at concentrations of dexamethasone as low as 10(-9) M. Tetrahydrocortisol, an inactive glucocorticoid metabolite that does not compete with dexamethasone binding to the receptor, did not enhance HSV infection at a high concentration (10(-5) M). This study demonstrates a direct effect of dexamethasone on corneal cell-HSV interaction in the absence of exogenous immunologic factors. This effect of dexamethasone may be mediated by the glucocorticoid receptor.

[Effect of the water-soluble antioxidant hydroxypyridine-6 on the intensity of lipid peroxidation in eye tissues in experimental ophthalmic herpes]

Lipid peroxidation (LPO) in eye tissues of rabbits with experimental herpetic keratitis was evaluated from the malonic dialdehyde content and chemiluminescence intensity. It appeared that during the critical phase LPO sharply increased in all the tissues under study and in anterior chamber humor. After administration of the synthetic water-soluble antioxidant, hydroxypyridine-6 the subconjunctival content of malonic dialdehyde and chemiluminescence intensity approached normal values accompanied by positive therapeutic effect.

[Pharmacokinetics and antiviral activity of riodoksol in an ointment and in ophthalmic drug films in ocular herpes]

A study was made on the pharmacokinetics in rabbit eye tissues of a new antiviral drug riodoksol in the form of ointment and biosoluble eye films. The pharmacokinetics of the drug was studied in eye tissues of normal rabbits and in those infected with herpes simplex virus. It was disclosed that four-fold application of 0.25% ointment produced the therapeutic concentration of the drug only in the cornea. Application of eye films made it possible to attain the therapeutic concentrations of riodoksol in the cornea and, within the first 3 hours, in the iris and humor of the anterior chamber. No differences were found in the drug concentrations in the tissues of intact and infected animals. Appraisal of the therapeutic efficacy of riodoksol regimens devised in experimental surface herpetic keratitis of rabbits has shown an adequacy of a single administration of eye films containing 0.5 mg of the substance and four-fold application of 0.25% ointment.

[Corneal lysosomes in experimental ophthalmoherpes]

Activity and intracellular distribution of lysosomal glucosidases (beta-glucosidase and beta-galactosidase) of the cornea as well as membrane permeability were studied in experimental herpetic keratitis. It was demonstrated that the action of herpes simplex entailed labilization of the lysosomal membranes of the cornea together with the decreased strength of lysosomal association with the enzymes thereby favouring the increased enzyme-substrate contact and excess destruction of cellular and exocellular glycosaminoglycans. The data obtained suggest that lysosomes participate in the pathogenesis of herpetic keratitis.

Histopathology and histochemistry of the superficial corneal epithelium in experimental herpes simplex keratitis

Three days after herpes simplex virus inoculation, an increased amount of DNA and RNA was observed in the superficial epithelium cells of rabbit cornea. Histochemical staining demonstrated the development of acid mucopolysaccharides and the destruction of reticulin. In the early stages, on rare occasions, giant polykaryocytes with multiple micronuclei were seen. From 1 week after infection, more and more cells became rounded and shrunken. Cytoplasm of these cells might contain DNA diffusely interspersed with RNA. This DNA is probably viral in nature. The nuclei of these cells varied in shape, size, and staining intensity. Nuclear fragments were often observed in the cytoplasm. Stainings for acid mucopolysaccharides were strongly positive in the rounded cells. These cells fused to form syncytia Variable-sized pseudopodialike processes containing DNA and RNA extend from some of the rounded and liquefied cells toward other cells. In the later stages, development of ghost cells was seen. Histochemical methods demonstrated the deposition of acid mucopolysaccharides on their cell membranes. Necrosis was more often present in the late stages. Nuclear debris and deformed cells were encountered in such areas. On the healing of the keratitis, 3 months after inoculation, the cell cytology and staining reactions reverted to normal.

A model for steroid effects in herpes keratitis

Dextran-Blue 2000 was used as a marker to determine the effect of steroids on large molecule transfer through the cornea. In superficially scarified corneas topically applied steroids greatly enhanced the transfer of this chromophore through the cornea in the in vivo state, but had little effect in vitro. This implies that the steroid effect is an active process. Since herpes simplex virus is approximately the same molecular weight and configuration as the chromophore used, this study explains one aspect of how steroids may be detrimental when used in the presence of this virus.