Clinical characteristics of acyclovir-resistant herpetic keratitis and experimental studies of isolates.

BACKGROUND: We treated two patients with dendritic keratitis that did not respond to acyclovir (ACV) ointment therapy. Their systemic immune status was normal: however, one patient had a long history of atopic disease and the other had previously undergone topical corticosteroid treatment. HSV-1 was isolated from the patients and inoculated into animals to investigate its viral pathogenicity and latent infection. METHODS: HSV-1 isolates from the patients were tested for drug sensitivity to acyclovir, ganciclovir, idoxuridine, trifluridine, foscarnet and interferon-beta in vitro. In in vivo studies, bilateral corneas of two New Zealand white rabbits and 10 BALB/c mice in each of four groups were infected by the respective viral isolates. The extent of corneal epithelial and/or stromal lesions produced by the viruses was evaluated. The trigeminal ganglial tissues of the mice were examined for viral latent infection by co-culture with Vero cells. RESULTS: Herpetic keratitis in both patients was characterized by prolonged clinical course, succeeded by various types of corneal lesions and ocular complications. In in vitro studies, the two HSV-1 isolates demonstrated cross-resistance to ACV, ganciclovir and/or idoxuridine. Both strains demonstrated weakly virulent corneal epithelial and/or stromal lesions in rabbits and mice. One isolate displayed delayed advent but prolonged course of epithelial lesions in rabbits. The latent infection incidences of the isolates in mice trigeminal ganglia were 6.25% (1/16) and 0% (0/18) respectively. CONCLUSION: Topical immune depression may induce ACV-resistant HSV-1 infection in the cornea, with a prolonged course in association with ocular complications. The prolonged infectious course of the viral isolates in the animal study partially supported the clinical demonstrations in the patient. The existence of latent infection by one ACV-resistant HSV-1 in its animals may indicate the possibility of its recurrence. Trifluridine may be an alternative choice for treating corneal epithelial lesions caused by ACV-resistant HSV-1.

Herpetic epithelial keratitis caused by acyclovir-resistant strain.

Dendritic keratitis occurred during oral acyclovir (ACV) therapy in a 60-year-old man. Corneal stromal edema and iritis were found at his first visit. Herpetic keratouveitis was suspected, based on clinical findings and previous history. Treatment with steroid eyedrops and ACV ointment was initiated. However, ACV [corrected] ointment was changed to oral ACV, since conjunctival ulcer occurred as an adverse effect of the ointment. Subsequently, he received long-term oral ACV medication and steroid eyedrops for recurrent keratitis. The fifth recurrence was also treated with oral ACV and steroid eyedrops. At this time, although the stromal keratitis had improved, there was an outbreak of dendritic keratitis. The lesion healed spontaneously after only a reduction in the steroid. The 50% effective dose (ED)50 of the isolated virus to ACV was 4.4 +/- 0.15 micrograms/ml (mean +/- SD), a level considered ACV-resistant in vitro. The clinical course of this case emphasizes that it is important to consider the route and duration of ACV administration and the use of steroids in the treatment of stromal keratitis or keratouveitis.

Emergence of cross-resistant herpes simplex virus following topical drug therapy in rabbit keratitis.

The acquisition of drug resistance in vivo was investigated by 7 serial passages (from P0 to P7) of herpes simplex virus (HSV-1) in rabbit cornea treated with either IUdR (idoxuridine), IDC (idoxycytidine), ACV (acyclovir), TFT (trifluridine), or Ara A (adenine arabinoside). Therapeutic failure was acquired gradually: at P3 for IUdR, at P4 for ACV and at P5 for TFT. At P7, viral thymidine kinase (TK) activity was reduced to 5.6% of the parental strain for IUdR, to 7.5% for ACV and to 4.6% for TFT treatment. No signs of clinical unresponsiveness occurred with IDC or Ara A. The in vitro determination of antiviral drug sensitivity performed by the dye-uptake assay on HSV isolates at each passage showed a correlation between the increase in the 50% effective dose (ED50) and the increase of ulcer area grade at each passage under antiviral drug (p less than 0.1). Both IUdR- and TFT-resistant HSV1 developed cross-resistances to TK dependent drugs. However ACV-resistant HSV1 did not show cross-resistance to other antiviral TK dependent drugs. The acquisition of the cross-resistances is discussed, and the practical implications in case of therapeutic failures are suggested.

Ocular acyclovir delivery by collagen discs: a mouse model to screen anti-viral agents.

Discs 1.6 mm in diameter trephined from corneal collagen shields were used to deliver acyclovir (ACV) to the cornea of mice inoculated with herpes simplex virus type 1 (HSV-1). In the first minute after application to the cornea, there was a 23% decrease of ACV in the discs. After the first minute, ACV clearance from the discs appeared to be exponential with a half-life of 21 minutes. Treatment given 3 times a day reduced HSV-1 titer in tear film, corneal tissue, and trigeminal ganglia. This animal model should be useful to conserve novel potential anti-viral drugs undergoing initial screening.

Chronic ocular zoster.

In a prospective open trial 40 patients suffering from acute herpes zoster ophthalmicus were treated with systemic acyclovir. An additional 10 patients were treated by topical acyclovir alone and dexamethasone eye-drops were administered to 5 of them to suppress ocular inflammation. In the topical treatment group the period of new skin lesion formation and progression of ocular inflammatory signs were significantly prolonged. Therapy with systemic acyclovir however resulted in a quick and complete resolution of ocular inflammation in all patients. Chronic ocular inflammation developed in 4 out of 10 patients treated with topical acyclovir. We consider chronic ocular zoster as a distinct clinical entity, possibly expressing a failing local immune response against VZV.

Antiviral drug sensitivity in ocular herpes simplex virus infection.

Thirty-nine herpes simplex virus (HSV) isolates were assayed for their sensitivity to 10 different antiviral agents. Of these 39 HSV isolates 10 were cultured from recipient buttons obtained at penetrating keratoplasty in patients with inactive stromal scarring due to recurrent herpetic keratitis, 25 were cultured from patients with conjunctival and ulcerative ocular infections, and the remaining four were laboratory strains with known drug sensitivity patterns, thus providing controls for the experiment. All but one of the 35 clinical isolates of HSV were type 1 and all were sensitive to the 10 antiviral agents. A single type 2 isolate from a young man with recurrent conjunctivitis proved to be resistant to a number of the antiviral agents. Since many of the clinical isolates had been exposed to multiple and protracted antiviral drug treatment, it is suggested that antiviral drug resistance in type 1 HSV ocular infection is not a significant problem.

[Experimental study of 472 herbs with antiviral action against the herpes simplex virus].

Using tissue culture method, the present work with its first-hand observation was primarily concerned with evaluating the antiviral effect of 472 traditional medicinal herbs (comprising raw material 10 mg/ml), through both initial (qualitative) and repeated (quantitative) screens, on type 1 herpes simplex virus. When dealing with water and alcoholic extracts, the effective herbs during initial screens were reduced after repeated screens by a range of 28.8-80.0%. Employing the basic value attained by the simultaneous route of drug administration, a stepwise declining of effective herbs would be: extratube route greater than simultaneous route greater than therapeutic route greater than preventive route. The more the routes of drug administration, the less the multiple-route simultaneous efficacy of a herb. Through repeated screens, 10 highly effective herbs were Aristolochia debilis, Artemisia anomala, Lindera strychnifolia, Patrinia villosa, Pinus massoniana, Prunella vulgaris, Pyrrosia lingua, Rhus chinensis, Sargussum fusiforme and Taraxacum mongolicum. Clinically, among the 78 cases of herpetic keratitis due to HSV1 treated by Pyrrosia lingua and Prunella vulgaris eye drops, a cure was effected in 38 and an improvement in 37, with 3 being of no benefit.

[Antiherpetic activity of Soviet-made phosphonic acid derivatives and their combinations with interferon inducers in a model of ophthalmic herpes]. / Protivogerpeticheskaia aktivnost' otechestvennykh proizvodnykh fosfonovoi kisloty i ikh sochetanii s induktorami interferona na modeli oftal'mogerpesa.

A comparative analysis of the effectiveness of national phosphonic acid derivatives (FUK and FMK) and acyclic nucleoside, acycloguanosine (Acg), as well as interferon (INF) inducers, lafarin and ridostin, was carried out on the model of herpetic conjunctivitis in rabbits and guinea pigs. Upon therapeutic-prophylactic administration, lafarin reduced the intensity of eye symptoms 2-fold as compared with the controls (infected but untreated guinea-pigs). In rabbits with herpetic conjunctivitis, the therapeutic schedule of the use of FMK (FUK) and Acg shortened the duration of the disease by 7 and 11 days, respectively, as compared with the control. The combined use of chemical drugs and INF inducers, lafarin or ridostin, reduced the intensity of the disease manifestations 3-fold and shortened the duration of the disease by 8-11 days. The survival rate was 80%-100%. Use of the combination of the two chemical drugs gave an additive effect. The synergistic effect was observed with FMK used in combination with lafarin.

Evaluation of (E)-5-(2-bromovinyl)- and 5-vinyl-1-beta-D-arabinofuranosyluracil (BrVaraU, VaraU) in the treatment of experimental herpes simplex virus type 1 keratitis in rabbits: comparison with (E)-5-(2-bromovinyl)-2'-deoxyuridine (BrVUdR).

The 5-substituted 1-beta-D-arabinofuranosyl (araU) analogues, (E)-5-(2-bromovinyl)-araU (BrVaraU) and 5-vinyl-araU (VaraU), which can be considered as structural analogues of (E)-5-(2-bromovinyl)-2'-deoxyuridine (BrVUdR), are potent and selective inhibitors of herpes simplex virus type 1 (HSV-1) replication in vitro. BrVaraU and VaraU have been compared with BrVUdR for their therapeutic effect on acute HSV-1 keratitis in rabbits. Both araU derivatives applied as 0.1% eyedrops suppressed the development of keratitis as monitored by the reduced number of herpes efflorescences. The healing effect of BrVaraU and VaraU was less pronounced than that of 0.1% BrVUdR eyedrops, the difference between BrVUdR and VaraU being statistically significant at the 10th day of treatment. As a further indication of the healing effect the number of cornea with opacities seen after cessation of drug treatment were 3.3, 7.4, 27.6 and 46.9% for the BrVUdR-BrVaraU-, VaraU- and placebo-treated eyes, respectively.

Effect of ketorolac on herpes simplex virus type one ocular infection in rabbits.

Corticosteroids can exacerbate viral ocular infections. Ketorolac tromethamine is an effective nonsteroidal anti-inflammatory agent that may be a useful substitute for corticosteroids following ocular surgery. In this study, rabbits ocularly infected with herpes simplex virus type 1 (HSV-1) were treated topically four times daily with 0.5 percent ketorolac or 0.1 percent dexamethasone for 7 days after infection. Severity of the infection was determined by scoring corneal opacity and HSV-1 corneal ulcerations with the Draize scale as well as iritis and conjunctivitis. Ten days after treatment ended both the corneal opacity scores (1.5 out of 4) and HSV-1 corneal ulcerations (0.3 to 0.7 out of 4) were similar for ketorolac and the vehicle, indicating no exacerbation of the infection, whereas with dexamethasone these scores were increased (3.6/4 and 3.4/4, respectively). Furthermore, both iritis scores (0.5/2) and conjunctivitis scores (1.3 to 1.4/10) were also similar for ketorolac and the vehicle, while dexamethasone increased both iritis (1.8/2) and conjunctivitis (4.3/10) compared to vehicle. Thus, ketorolac appears to be an anti-inflammatory agent that does not worsen viral ocular infection.

The antiviral effects of rose bengal and fluorescein.

We evaluated the antiviral effects of rose bengal and fluorescein sodium. The direct antiviral activity was determined by an in vitro direct neutralization assay. The 50% inhibitory dose was 16 micrograms/mL for rose bengal and 460 micrograms/mL for fluorescein. The in vivo antiviral effects of these drugs were determined in the mouse herpetic keratitis model. Following topical application, rose bengal reduced surface virus titers (swabs) 1 million-fold, and residual ocular virus (eye homogenates) 32-fold, compared with controls. No infectious virus was recovered by swabbing after topical application of rose bengal. Fluorescein had no significant effect on virus replication. Thus, rose bengal, unlike fluorescein, has significant antiviral activity, and the diagnostic use of rose bengal prior to viral culture may preclude a positive result. Also, the use of rose bengal to grade keratitis in the study of new antiviral agents should be discouraged.

Experimental thymidine kinase-deficient HSV-1 keratitis: therapeutic attempts.

Trifluridine (TFT) and a structurally related analogue, 5-fluoro-2'-deoxyuridine (FDU), were investigated for their efficacy in the topical treatment of experimental keratitis caused by thymidine kinase-positive (TK+) and thymidine kinase-deficient (TK-) herpes simplex virus type 1 (HSV-1) strains. Bromovinyldeoxyuridine (BVDU) was used as a reference compound. Both 0.2% BVDU and 0.2% TFT eyedrops produced a highly significant healing of TK+HSV-1 keratitis as compared to the placebo and 0.2% FDU eyedrops (P much less than 0.005), whereas the latter compound did not differ from placebo eyedrops. In the treatment of TK HSV-1 keratitis, none of the drugs exhibited a beneficial healing effect, although the virus strain used was inhibited in vitro by TFT and FDU at a very low concentration (0.02-0.04 microgram/mL).

Acyclovir (Zovirax) ophthalmic ointment: a review of clinical tolerance.

Twenty nine published clinical trials with acyclovir (ACV) ophthalmic ointment in the treatment of herpes simplex virus (HSV) corneal disease have been reviewed in which ACV has been demonstrated to be effective in the treatment of simple dendritic ulcers, geographic ulcers, deep corneal HSV infections and ocular disease associated with herpes zoster (VZV) infection affecting the ophthalmic division of the trigeminal nerve. 998 patients were studied. The most commonly occurring adverse reactions were superficial punctate keratopathy (in 9.8% of patients) and burning or stinging on application of the ointment (4%). ACV ophthalmic ointment was first licensed for the treatment of HSV infections of the eye in September 1981. Spontaneous reports of adverse reactions to ACV ophthalmic ointment to both the UK Committee on Safety of Medicines and the Wellcome Group Adverse Reactions Reporting Centre total 43 cases. These include conjunctivitis, inflammation and pain in the treated eye. In this time it is estimated that there have been approximately one million exposures to the ointment. Thus in general use, tolerance to ACV treatment has been extremely good, and clinical trial data demonstrate that it compares favourably with alternative therapies for HSV corneal disease.

Side effects in the treatment of herpetic keratitis.

Various side effects due to antiherpetic drugs observed in the last ten years in our department were studied. A total of 132 patients were treated with 5-iodo-2'-deoxyuridine (IDU), 69 with trifluorothymidine (F3T), 58 with acyclovir (ACV) and 33 with adenine arabinoside (ara-A). Patch tests were routinely done when patients exhibited contact dermatitis. Of the patients treated with IDU, 3 (2.3%) showed contact dermatitis, 2 (1.5%) follicular conjunctivitis and 1 (0.8%) punctate keratopathy. Of the patients treated with F3T, 7 (10.1%) exhibited contact dermatitis and 1 (1.4%) follicular conjunctivitis. In the group treated with ACV, 2 (3.4%) patients showed punctate keratopathy. The patients who received ara-A did not show any side effects. We found that F3T caused contact dermatitis more frequently in Japanese people than Europeans. These side effects were resolved by switching to another anti-herpetic drug without the occurrence of cross-allergy. Therefore, switching to another drug is strongly recommended when patients exhibit side effects in the treatment of herpetic keratitis. Other complications were allergy to atropine and to drug preservative.

Efficacy of glycoprotein inhibitors alone and in combination with trifluridine in the treatment of murine herpetic keratitis.

The present study examined the anti-herpetic effect of the glycoprotein inhibitors, hydroxynorvaline and 2-deoxyglucose, alone and in combination with trifluridine on murine ocular herpes. Following ocular inoculation with a large dose of HSV-1 RE strain (10(6) pfu), ICR mice were treated during the acute infection with different therapeutic regimens, and their efficacy was evaluated by ocular virus titers, clinical grading of blepharo-conjunctivitis and histological evaluation of stromal keratitis and iridocyclitis. The results following a large dose HSV-1 inoculum demonstrated that trifluridine was the best single therapeutic agent. Hydroxynorvaline and 2-deoxyglucose had no effect at all. Combination therapy of the glycoprotein inhibitors with trifluridine was no better than trifluridine alone. The mouse HSV-1 keratitis model proved to be an effective, economical alternative to the rabbit model for the evaluation of new antiviral agents.

[Development and practical use of new experimental models of the various forms of herpetic infection]. / Razrabotka i prakticheskoe ispol'zovanie novykh éksperimental'nykh modelei raznykh form gerpeticheskoi infektsii.

New experimental models of neurological herpes in cotton rats and genital herpes in male guinea pigs have been developed which are more adequate to the corresponding human diseases, and models of ophthalmic herpes in rabbits and guinea pigs have been improved. These models may be used for screening and evaluation of the effectiveness of drugs for herpes. A high activity against herpes of bromovinyldeoxyuridine and acyclovir has been verified, a marked therapeutic effect of Soviet monophosphates ara-A, ara-C, and original silur preparation in some forms of herpes infection has been demonstrated.