Ocular disease pattern induced by herpes simplex virus is genetically determined by a specific region of viral DNA.

The pattern of ocular disease produced in the rabbit eye by HSV-1 (F) and HSV-1(MP) strains and recombinants F(MP)A, F(MP)B, F(MP)C, F(MP)D, F(MP)E, and F(MP)F was studied. The characteristics of ocular herpetic disease such as morphology of dendritic ulcers, severity of epithelial disease and incidence and duration of stromal disease produced in the rabbit eye are genetically determined by the virus strain. Our studies show that transfer of a defined part of the genome of the stromal disease-producing virus, HSV-1(MP), to the genome of an epithelial disease-producing virus, HSV-1(F), yielded recombinants with one or more of the disease characteristics of the donor strain. Specifically, recombinant F(MP)D produced lesions characteristic of the donor HSV-1(MP) strain; recombinants F(MP)C and F(MP)E produced stromal disease approaching the severity of the disease produced by the donor HSV-1(MP) strain, and only recombinants F(MP)A and F(MP)B retained the typically elongate lesions of the recipient HSV-1(F), whereas the recombinant strain F(MP)F produced no disease. The viral functions pertaining to the ocular disease pattern map between 0.70 and 0.83 map units in HSV-1 DNA within the BglII F DNA fragment. The pattern of stromal disease is independent of the production of glycoprotein C and fusion of HEp-2-infected cells. The functions relating to these aspects of ocular disease segregate but are closely linked.

Recurrent herpes in the rabbit and man.

Herpesvirus was present in secretory glands and frequently in tears of rabbits with recurrent herpetic keratitis even in the absence of corneal lesions. In normal people, herpesvirus could be cultured from saliva and tears. Chronic virus multiplication in structures such as the lacrimal and salivary glands, rather than latency, may cause recurrent herpetic disease.

Corneal endothelium damage with intraocular lenses: contact adhesion between surgical materials and tissue.

Intraocular lenses destroy corneal endothelial cells by contact adhesion between the acrylic lens and endothelial surfaces during cataract surgery. Glass and rubber surgical glove surfaces produce similar cell damage. This phenomenon may be important in many surgical procedures and appears to be preventable if a hydrophilic polymer interface is interposed between contacting tissue and the surfaces of materials used.

Herpesvirus type 2 in the male genitourinary tract.

A population study of 190 randomly selected male patients with no history of genital herpesvirus infection revealed a high incidence of herpesvirus type 2 in genitourinary specimens. This indicates that men serve as a reservoir of genital herpesvirus.

In vitro transformation of hamster cells by herpes simplex virus type 2 from human prostatic cancer cells.

A cell-associated herpes simplex virus type 2 found in a human prostatic carcinoma induced in vitro transformation of hamster embryo cells. The transformed cells (YW-74) have been shown to be hamster cells by karyotype analysis. Their epithelial morphology and growth pattern, which are different from the parental cell, have remained stable through cell passages. The presence of herpesvirus antigens in the transformed cells was determined by specific immunofluorescence and colony inhibition tests. Immunofluorescence staining with specific anti-herpes simplex virus type 2 serum showed an intense and distinctive nuclear and perinuclear fluorescence in about 95% of the transformed cells. In addition, exposure of these transformed cells to herpes simplex virus type 2-sensitized lymphocytes resulted in inhibition of growth and colony formation, while no effect was seen with nonsensitized lymphocytes. Both observations are consistent with the involvement of herpesvirus type 2 in the transformation event. This virus, which does not produce a lytic infection and is not found either in extracellular spaces or supernatant fluid of the transformed cell cultures, is unique in the fact that it is cell associated, noncytopathogenic, and capable of transforming cells in vitro, and its antigens are clearly demonstrated in the transformed cells.

Treatment of viral diseases of the cornea and external eye.

Ocular virus infections remain an important cause of corneal and external disease. Herpes simplex, the most important, is easily treated when it is confined to the epithelium. New studies indicate that herpetic stromal disease and iritis are effectively treated with a combination of corticosteroid and antiviral without additional risk. Recurrences of ocular herpetic disease can be reduced with acyclovir given orally; the benefit seems to be greatest in patients who have had at least one episode of stromal keratitis. Herpes zoster can be treated with either acyclovir or famciclovir, but to be effective, treatment must be initiated within 72 hours of onset. Early treatment reduces the risk of post-herpetic neuralgia and may reduce the risk of ocular complications. Adenovirus infection (epidemic keratoconjunctivitis) is often spread by the ophthalmologist. New medications such as cidofovir appear to be effective against the adenoviruses in non-human systems and may have some effect in man, although previously, drugs that appeared to have an effect in vitro have proven to be ineffective in the clinical setting.

Prolonged survival of corneal allografts incubated in alloantibody fragments.

BACKGROUND: In this study, we determined the binding characteristics of F(ab')2 alloantibody fragments to corneal antigens and assessed the capacity of these antibody fragments to protect corneal allografts from immune attack. METHODS: Goat anti-rabbit alloantibodies were pepsin-digested and labeled with 125I, and the time course of association and dissociation of the F(ab')2 fragments was determined. Corneal allografts were incubated in unlabeled F(ab')2 fragments and transplanted into allogeneic recipients, and the graft survival times were recorded. RESULTS: Binding of radiolabeled F(ab')2 fragments to rabbit cornea cells reached a maximum at 12 hr. At 32 degrees C (rabbit corneal temperature), the radiolabel eluted rapidly from the cornea, reaching baseline at 72 hr. At 4 degrees C (corneal graft storage temperature), significant amounts remained associated with the cornea at 96 hr. Mean survival time for grafts incubated in F(ab')2 anti-rabbit fragments was significantly greater than that of grafts incubated in nonimmune F(ab')2 fragments. Three of the corneal allografts incubated in goat F(ab')2 anti-rabbit fragments survived for 100 days, whereas the longest surviving control allograft incubated in goat F(ab')2 nonimmune fragments was rejected on day 24. Preincubation of corneas in unlabeled, immune F(ab')2 fragments followed by incubation in radiolabeled, immune F(ab')2 fragments suggested that antigen masking was not a factor in the prolongation of graft survival. CONCLUSION: Based on the binding and release kinetics and the graft survival times, it appears that the protective effect of immune F(ab')2 fragments extends well beyond the binding interval of the antibody fragments to corneal cell membranes.

Herpetic keratitis. Proctor Lecture.

Although much needs to be learned about the serious clinical problem of herpes infection of the cornea, we have come a long way. We now have effective topical antiviral drugs. We have animal models which, with a high degree of reliability, clearly predict the effect to be expected clinically in man, as well as the toxicity. We have systemically active drugs and the potential of getting highly active, potent, completely selective drugs, with the possibility that perhaps the source of viral reinfection can be eradicated. The biology of recurrent herpes and stromal disease is gradually being understood, and this understanding may result in new and better therapy of this devastating clinical disease.

Pathology of the corneal endothelium.

Clinical specular microscopy has indicated that human cell healing occurs by spreading, there is a limited healing reserve, and premature cell loss is the equivalent of a "premature aging" that may lead to later decompensation. This instrument has been useful in studying healing and cell damage from surgery, drugs, and special procedures such as intraocular lens insertion. It pointed out extensive cell loss at the time of intraocular lens insertion, and subsequent studies have indicated that at least part of this cell loss may be due to the methacrylate surface of the lens. Laboratory studies suggest that coating that surface can prevent this component of cell loss. The magnitude of benefits to be found from such coating requires further clinical study.

A mathematical description of causative factors and prevention of elevated intraocular pressure after keratoplasty.

In keratoplasty with grafts the same size as the recipient bed, tight sutures and thick recipient corneal periphery distort the angle and may collapse the filtering meshwork. This can cause very high postoperative pressures, which can be avoided by the use of donor grafts larger than the recipient bed. These relationships can be mathematically predicted.

Lack of levamisole effect on experimental herpes keratitis.

Levamisole, which is an anthelminthic, can restore depressed cell-mediated immunity (CMI) under some circumstances. In a controlled trial of experimental herpetic keratis in rabbits, levamisole was found to have no significant effect on acute herpetic keratitis or its recurrence rate. This is consistent with previous findings that other nonspecific CMI stimulation had no effect on recurrences of experimental herpes keratitis. Because of the known tendency of levamisole to produce agranulocytosis, we believe it should not be used in man unless proven effective in a carefully controlled double-blind study.

Topically applied cyclosporine in azone prolongs corneal allograft survival.

The purpose of this study was to develop and test a topical ocular delivery system for the immunosuppressive drug cyclosporine. To this end, cyclosporine was dissolved in the penetration enhancer, Azone, and applied topically to allografted rabbit eyes. The concentration of cyclosporine in the cornea, the aqueous humor, and blood of the treated rabbits was determined by radioimmunoassay. The effect of the cyclosporine-Azone preparation on the survival of corneal allografts was assessed by clinical evaluation of the grafts and by histopathologic and immunohistologic evaluation of the cellular infiltrate in the grafts. Clinically significant concentrations of cyclosporine were measured in the treated corneas but little or no drug was found in the aqueous humor or blood of the treated animals. Cyclosporine in Azone resulted in suppression in the severity and incidence of graft rejection. The suppression of graft rejection was borne out by the immunohistologic observations. Cyclosporine-treated grafts contained significantly fewer infiltrating T lymphocytes than did the drug/solvent-treated allografts, indicating that the topical application of cyclosporine actively inhibited the entry of T cells into the grafts. This study, for the first time, presents a solvent that is apparently not toxic but is effective in delivering immunologically active concentrations of cyclosporine following topical application to the cornea.

Corneal nerves are necessary for adrenergic reactivation of ocular herpes.

Herpes simplex virus type 1 (HSV-1) can infect the cornea and achieve ganglionic latency. HSV-1 can later be activated by a variety of effectors although the exact mechanism of reactivation is unknown. Rabbits harboring latent HSV-1 strain McKrae can be induced to shed virus by ocular iontophoresis of epinephrine to the cornea. No studies have been done to investigate if corneal nerves are necessary for epinephrine induction of HSV-1 ocular shedding. We did penetrating keratoplasty (PKP) in one eye each of 23 rabbits; the other eye served as an unoperated control. The surgery effectively denervates the area of the transplant for up to 90 days. Eighteen rabbits carrying latent HSV-1 strain McKrae received corneas from uninfected rabbits. Five uninfected rabbits with no latent virus received corneas from rabbits harboring latent HSV-1. On days 10-14 after penetrating keratoplasty, 24 eyes in the HSV-1 latent group and all ten uninfected eyes received iontophoresis of 0.01% epinephrine (0.8 mAmps for 8 min or 0.6 mAmps for 6 min) once daily for 3 days by means of an eye cup whose diameter was less than the diameter of the transplant. Six rabbits in the HSV-1 latent group received intravenous injections of cyclophosphamide (75 mg/kg) and dexamethasone (4 mg/kg). Following iontophoretic or immunosuppressive induction, the eyes were swabbed daily for 9 days. Of the 12 rabbits with latent virus which were treated by iontophoresis, one of the transplanted eyes and eight of the nontransplanted eyes were induced to shed virus. The mean duration of shedding in the nontransplanted eyes was 3.25 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Dextran flux in M-K medium-stored human corneas.

Dextran, with a minimal molecular weight of 40,000, can pass in and out of the corneal endothelium during storage in M-K medium. Results suggest that the degree of penetration of dextran depends on the length of storage and the condition of the endothelium.

The lack of effect of tunicamycin and 2-deoxy-D-glucose on corneal stromal herpes in rabbits.

A rabbit model for herpes simplex virus (HSV) stromal keratitis, produced by intrastromal injection of live virus, was used to evaluate the effects of tunicamycin and 2-deoxy-D-glucose therapy. In vivo and in vitro evidence suggests that HSV strains that produce stromal disease secrete relatively large amounts of highly antigenic glycoproteins. Also, various studies have shown that tunicamycin and 2-deoxy-D-glucose inhibit the production of complete HSV-specific glycoproteins. Thus, these drugs might be capable of mitigating the clinical manifestations of HSV stromal keratitis by reducing the antigenic load. However, when topical therapy with tunicamycin and/or 2-deoxy-D-glucose was begun in rabbit eyes, the day after intrastromal inoculation of live RE strain HSV and several days before the appearance of stromal disease, no difference in the clinical course of herpetic ocular disease was seen between the experimental (treated) and control (untreated) groups.

A primate model of human corneal transplantation.

Human donor corneas were used for penetrating keratoplasty in one eye of each of 12 rhesus monkeys. In six animals, a 9.5-mm cornea was sutured into a 9.0-mm recipient bed by means of interrupted 10-0 nylon sutures. Six other animals received a 6.5-mm cornea in a 6.0-mm bed. Biomicroscopy, pachymetry, and specular microscopy revealed two distinct healing patterns. Of the six eyes receiving the smaller grafts, five showed prompt, stable clearing and thinning of the grafts with endothelial cell densities ranging from 850 to 1600 cells/mm2 Two of the six animals receiving larger grafts developed fibrinous reactions in the immediate postoperative period, and the grafts never cleared. Three showed a satisfactory early course, but after 10-16 days, developed endothelial keratic precipitates, anterior chamber reaction, and progressive graft edema. The sixth graft remained technically satisfactory 1 year later. This study indicates that the application of small human donor grafts in monkey eyes can provide a useful, clinical model for the future exploration of the response of human corneal transplants to materials such as epidermal growth factor and for the study of surgical manipulation of postkeratoplasty astigmatism.

Cold stress-induced recurrences of herpetic keratitis in the squirrel monkey.

PURPOSE: Models of recurrent herpetic keratitis that depend on tissue damage or immunosuppression have been described. The authors report a model that depends only on minimal temperature stress to produce clinical recurrences in a small primate. METHODS: Squirrel monkeys (Saimiri sciureus) infected by the ocular route with the Rodanus strain of herpesvirus type 1 (HSV-1) were exposed to temperatures approximately 5 degrees C lower than the usual ambient temperature for periods as short as 12 hours. RESULTS: The corneas showed more or larger lesions typical of recurrent herpetic keratitis than are usually seen in these animals under normal conditions. Statistical analysis showed that there were significantly higher frequencies of epithelial keratitis at 18 degrees C and 20 degrees C (P < 0.0001). CONCLUSIONS: A minimal temperature change produced significant recurrences in this small animal within a short time. Tissues were not damaged to produce the recurrences. This approach may provide an efficient primate model for rapid testing of drugs to prevent clinical recurrence of ocular herpetic keratitis.

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.

The effect of collagen cross-linkage inhibitors on rabbit corneas after radial keratotomy.

The inhibition of collagen cross-linkage by beta-aminopropionitrile (BAPN) and D-penicillamine was tested in an attempt to enhance the myopic correction achieved by radial keratotomy. Two groups of six rabbits each underwent radial keratotomy in both eyes; one eye of each rabbit was treated with BAPN (33% in white petrolatum) or D-penicillamine (1.5 M in sterile water) three times a day for 6 weeks, while the other eye received only vehicle. In spite of previous reports of positive results with BAPN, neither BAPN nor penicillamine was found to affect keratometry readings or corneal topography after radial keratotomy. Our results suggest that factors other than collagen cross-linkage exert major influences in determining the outcome of this refractive procedure.

Trifluridine decreases ocular HSV-1 recovery, but not herpetic lesions after timolol iontophoresis.

To determine the effect of a topically applied antiviral agent on shedding of herpes simplex virus type 1 (HSV-1) into the tear film and corneal epithelial lesions, ten rabbits latently infected with HSV-1 were subjected to transcorneal iontophoresis of 0.01% timolol once a day for 3 consecutive days to induce viral shedding and lesions. Iontophoretic induction was performed similarly in five uninfected rabbits as controls. Half of the infected rabbits and all of the uninfected controls received topical 1.0% trifluridine five time a day for 9 days, beginning the day after the first iontophoresis. All eyes were examined daily for 10 days by slit-lamp biomicroscopy and tear film samples collected on swabs were analyzed for virus. In the infected rabbits, the eyes treated with trifluridine had significantly fewer swabs positive for HSV-1 than the untreated eyes (P less than 0.001); however, there was no significant difference in the numbers of lesions in the treated and untreated eyes. The uninfected controls had no positive swabs and developed no lesions. These results suggest that topical treatment with trifluridine may reduce recovery of HSV-1 from the tear film, but does not affect the incidence of iontophoretically induced corneal epithelial lesions.