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Biomedical subjects

E Romanowski

Publications and source records attributed to E Romanowski.

At least 19 recordsLinked to original sources
PubMed1998

Efficient reactivation of latent herpes simplex virus type 1 infection by excimer laser keratectomy in the experimental rabbit ocular model.

PURPOSE: To investigate the role of excimer laser keratectomy as a trigger for the reactivation of latent HSV type 1 (HSV-1) in the New Zealand rabbit ocular model. There are conflicting reports in the current literature about reactivation of HSV-1 after excimer laser photoablation. METHODS: New Zealand rabbits were inoculated topically with HSV-1 McKrae or W strain in each eye, and culture-positive dendritic keratitis was documented on day 7. After the establishment of latency (21+ days), animals were divided into three groups: group I animals underwent excimer laser photoablation in each eye; group II animals received intrastromal injections of sterile water to act as positive controls (a standard method); and group III animals received no treatment and represented spontaneous shedders. All eyes were swabbed daily from days 1 through 10 and plated on A549 cells. Recovery of HSV-1 on days 1 through 10 postinduction was analyzed to compare the efficiency of the different methods of viral reactivation. RESULTS: Reactivation of latent HSV-1 after excimer treatment was observed in nine (45%) of 20 eyes and was equivalent to the rate of reactivation seen in the positive control animals (eight [44.4%] of 18 eyes) (P=.99). Both of these rates were significantly greater than those of the untreated animals (one [5.6%] of 18 eyes) (P=.018). CONCLUSION: Excimer laser keratectomy appears to be an efficient trigger for the reactivation of latent HSV-1 in the New Zealand rabbit ocular model.

Animals↗
PubMed1993

Prolonged recovery of desiccated adenoviral serotypes 5, 8, and 19 from plastic and metal surfaces in vitro.

BACKGROUND: Prevention of the spread of epidemic keratoconjunctivitis (EKC) at eye care facilities (doctors' offices, clinics, hospitals) has been a major public health goal for ophthalmology for more than 50 years. The authors explored a potentially contributing attribute of the adenovirus serotypes that cause EKC. Specifically, they investigated the capacity of different clinical and laboratory ocular serotypes (AD8, 19, and 5) to survive for extended periods of time in a desiccated state. METHODS: Twenty microliters containing 2000 plaque-forming units of different ATCC laboratory adenoviral ocular serotypes (AD8, 19, and 5) and clinical isolates (AD8 Cray, AD19 Kowalski, and AD5 McEwen) were inoculated onto 7-mm plastic disks and 6-mm aluminum foil disks and were allowed to completely desiccate. At weekly intervals up to 7 weeks, eight desiccated virus-inoculated plastic or metal disks per serotype were added to tissue culture medium, and the amount of recoverable virus was determined by plaque assay on A549 cells. RESULTS: Ocular adenoviral serotypes AD8, 19, and 5 could be recovered up to 49 days from plastic, and 35 to 49 days from metal. Sufficient virus concentrations (> 100 plaque-forming units/disk) to be clinically infectious were recovered up to 28 days. Differences in recovery among serotypes (AD19 > AD5, AD8) were demonstrated, but laboratory and clinical isolates of the same serotype were usually comparable. CONCLUSIONS: Ocular isolates of adenovirus that cause EKC are much harder than previously suspected, and the capacity to survive in a desiccated state may possibly play some role in office-based mini-epidemics of EKC.

Adenoviruses, Human↗
PubMed1992

Pretreatment with topical 0.1% (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine inhibits adenovirus type 5 replication in the New Zealand rabbit ocular model.

Currently there is no clinically effective antiviral agent for the prevention or treatment of ocular adenoviral infections. Using a paired-eye, masked design, we tested the antiviral efficacy of topical 0.1% (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine in the New Zealand rabbit ocular model after topical and intrastromal inoculation with 100 microliters (4 x 10(5) plaque-forming units per eye) of adenovirus type 5 McEwen, a clinical isolate. Prevention studies involved pretreatment (six times a day) 1 day before inoculation and continuing for 4 additional days. Compared with the control eyes, the pretreated eyes showed a significant reduction in the peak viral eye titers on days 3, 4, 5, and 7 after treatment (p < 0.03-0.005), and a reduction in the duration of viral sheeding (p < 0.02). Rebound increase in adenoviral titers was detected in five of 20 eyes (25%) after cessation of treatment, suggesting a therapeutic effect and a need for further studies to optimize the treatment regimen.

Adenoviridae↗
PubMed1992

An ocular model of adenovirus type 5 infection in the NZ rabbit.

Ocular adenoviral infections occur worldwide, and currently, there is no ocular animal model for evaluating new antivirals or studying pathogenesis. With a paired-eye design, an ocular model was developed in 32 New Zealand rabbits following topical and intrastromal inoculation with a clinical isolate of adenovirus type 5 (Ad5 McEwen). Clinical signs of infection--conjunctivitis, corneal edema, subepithelial infiltrates, and iritis--and seroconversion were evaluated. Replicating virus on the ocular surface was determined by serial ocular titers. Reproducible acute ocular infection was demonstrated in 32 of 32 infected eyes (100%), with mean viral replication lasting for 8.3 days. Peak ocular viral titers (10(3) plaque forming units/ml) were achieved on day three after inoculation and represented a 2 log increase (100 times) over day one. Ocular viral replication was associated with acute conjunctivitis (24/34 eyes, 75%), and delayed-onset presumed immune-mediated clinical disease was associated with: blepharoconjunctivitis (21/32 eyes, 66%), iritis (29/32 eyes, 91%), corneal edema (32/32 eyes, 100%), and subepithelial corneal infiltrates (30/32 eyes, 94%). Seroconversion was demonstrated in 26 of 31 rabbits (84%). The study concludes that a potentially useful animal model of adenoviral ocular infection can be attained.

Adenoviridae Infections↗
PubMed1991

Inhibitory effect of (S)-HPMPC, (S)-HPMPA, and 2'-nor-cyclic GMP on clinical ocular adenoviral isolates is serotype-dependent in vitro.

Currently, there is no effective treatment for ocular adenoviral infections that occur in epidemics worldwide, produce significant patient morbidity, and cause substantial economic losses. We tested several new antivirals in vitro, and found that (S)-HPMPC, (S)-HPMPA, and 2'-nor-cyclic GMP demonstrated significant serotype-dependent inhibitory activity by plaque reduction assay (ID50 = 0.017-17.0 micrograms/ml) against common clinical ocular isolates and standard adenoviral serotypes (Ad 1, Ad 5, Ad 8, and Ad 19). (S)-HPMPC was the least toxic (CD50 in A549 cells = 306 micrograms/ml), and (S)-HPMPC and (S)-HPMPA had high selectivity indices.

Adenine↗
PubMed1991

Replication of ocular isolates of human adenovirus is serotype-dependent in rabbit corneal organ culture.

The goal of the present in vitro study was to determine the ability of unadapted human adenoviral ocular isolates to replicate in the rabbit cornea. Rabbit corneas grown in organ culture (24 well plate) were inoculated topically with 50 microliters (5 x 10(5) pfu) of different ocular adenoviral serotypes (ATCC and clinical isolates). Control wells (no cornea present) were inoculated in a similar fashion. Viral replication was determined by serial aliquots titrated on A549 cells. We demonstrated sustained viral replication over time of all isolates (100%) of Ad1, 2, 5, 6, 8, 9, 11 and 37 tested. No isolates (0%) of Ad3, 7A, 19, and 4 demonstrated replication in our model. Peak titers varied among successful serotypes from 10(2) pfu/ml (Ad11) to 10(5) PFU/ml (Ad5), and among different isolates of a given serotype. We conclude that the ability of unadapted human Ad serotypes to replicate in rabbit corneas was serotype-dependent, and that subgroup C (Ad1, 2, 5, and 6) appeared to be the most successful subgroup.

Adenoviruses, Human↗
PubMed1990

Host species and strain differences affect the ability of an HSV-1 ICP0 deletion mutant to establish latency and spontaneously reactivate in vivo.

HSV-1 latency and reactivation were studied in vivo by spontaneous and iontophoresis-induced ocular viral shedding in New Zealand rabbits, Balb/c and A/J mice latently infected with wild-type KOS, and dl x 3.1, a progeny ICP0 deletion mutant. The presence of trigeminal ganglionic latency was demonstrated by the in vitro methods of cocultivation and in situ hybridization. Although the efficiency of ganglionic latency was significantly less (P less than .0001) for dl x 3.1 than for KOS in both mice and rabbits, only dl x 3.1 shed spontaneously in the NZ rabbit. Iontophoresis of adrenergic agents failed to induce reactivation and ocular viral shedding of KOS or dl x 3.1 in mice or rabbits. The establishment of latency and reactivation of KOS and dl x 3.1 was dependent on the host animal. We conclude that host factors as exemplified by host species and host strain differences significantly affected the ability of KOS and dl x 3.1 to establish latency, to reactivate, and to shed spontaneously. ICP0 expression was not required for the establishment or maintenance of latency, nor was it required for the reactivation of latent HSV-1. Furthermore, the biological activity of KOS and dl x 3.1 during latency in vivo did not correlate with latency studies based on in vitro methods.

Animals↗
PubMed1990

The effect of alpha blockade on iontophoresis-induced ocular shedding of latent HSV-1 W in different host animals.

Previous studies demonstrated that non-specific beta blockade promoted ocular shedding of latent HSV-1 in the mouse and rabbit iontophoresis models. The present study examined the effect of topical alpha blockers, thymoxamine and corynanthine, on reactivation and induced ocular shedding of latent HSV-1 W in different host animals. Latent trigeminal ganglionic infection was established in Balb/c mice and New Zealand rabbits following corneal inoculation with HSV-1 W strain, and later confirmed by co-cultivation. Treatment with coded eye drops (thymoxamine, corynanthine or BSS was begun one day prior to iontophoresis induction and continued BID OU for 5 days. Reactivation and recovery of latent HSV-1 was determined by daily ocular swabs, and characteristic HSV-1 cytopathic effect in Vero cells. In Balb/c mice, topical administration of thymoxamine 0.5% or corynanthine 5% significantly reduced the number of virus-positive eyes, virus-positive mice, and total virus-positive swabs per experiment, whereas the inhibitory effect was minimal in NZ rabbits. We conclude that alpha blockade may alter the reactivation signal that is mediated via the adrenergic system, and that different host factors (as expressed in different species) may play an important role in this process.

Administration, Topical↗
PubMed1990

Vanadate promotes reactivation and iontophoresis-induced ocular shedding of latent HSV-1 W in different host animals.

Vanadate is a potent inhibitor of calcium stimulated ATPase, Na, K-ATPase, and may have adrenergic activity. Using the iontophoresis method, we compared vanadate to a BSS control and the standard iontophoresis model (6-hydroxydopamine/epinephrine) by measuring induced ocular shedding of latent HSV-1 in different host animals. Latent trigeminal ganglionic infections were established in Balb/c mice and New Zealand rabbits following corneal inoculation with HSV-1 [W] strain, and later confirmed by cocultivation. Latently-infected animals (greater than 1 month post-infection) were divided into three treatment groups. Each group was iontophoresed with BSS, vanadate 1% or 6-HD 1%, and then treated topically for 10 days with BSS, vanadate or epinephrine respectively. Reactivation and recovery of latent HSV-1 was detected by daily ocular swabbing, plating, and observing progressive viral growth in Vero cells. The vanadate group had more virus-positive eyes than the BSS control group in mice, (8/32 vs. 1/32 P less than .01), and also in rabbits (14/20 vs 6/22 P less than .01). Virus-positive animals and total positive swabs were also higher for vanadate than BSS in both mice and rabbits. Furthermore, while vanadate was associated with fewer virus-positive eyes than 6-HD & EPI (8/32 vs. 17/32 P less than .02) in mice, there were no significant differences in rabbits. We conclude that vanadate promotes ocular shedding of latent HSV-1, and may act through an adrenergic mechanism.

Animals↗
PubMed1990

A herpes simplex type 1 ICPO deletion mutant demonstrates diminished pathogenicity during acute ocular infection in different host animals.

We compared a previously characterized herpes simplex type 1 alpha 0 deletion mutant, dlx3.1, which produced no functional ICP0, with its wild-type parental strain, KOS, during acute ocular infection of different host animals. Acute pathogenicity of the viral strains in NZ rabbits, Balb/c and A/J mice was evaluated by keratitis scores, ocular and trigeminal ganglionic viral titers, and host survival. We found that dlx3.1 was significantly less pathogenic than KOS. Host differences proved very important in the evaluation of acute pathogenicity. A species-dependent enhancement of ocular pathogenicity was demonstrated for dlx3.1 following a larger viral inoculum and host immunosuppression. We conclude that alpha 0 gene function appears to play an important role during acute ocular pathogenicity of HSV-1 in animal models. Furthermore, in vivo pathogenicity studies contribute important information in the evaluation of essential viral gene function.

Acute Disease↗
PubMed1990

A fast, simple reactivation method for the study of HSV-1 latency in the rabbit ocular model.

We developed a simple, fast, economical, and versatile reactivation method for the study of herpes simplex virus type 1 (HSV-1) latency in the rabbit ocular model. Intrastromal injection of sterile, deionized water induced reactivation and ocular shedding of latent HSV-1 in 21 of 27 eyes (78%) in 93% of New Zealand rabbits. Other control groups (eg, anterior chamber injection of sterile, deionized water; topical administration of sterile, deionized water; intrastromal injection of air; and intrastromal needle track), were less efficient in reactivating latent HSV-1. Although the mechanism of reactivation in this model is unknown, the reactivation signal may be related to the relative amount of corneal trauma.

Administration, Topical↗
PubMed1988

RNA complementary to herpes simplex virus type 1 ICP0 gene demonstrated in neurons of human trigeminal ganglia.

Recent studies with mice have demonstrated abundant RNA transcripts which are complementary (antisense) to the herpes alpha gene ICP0 in latently infected ganglia. We investigated the situation in unselected human trigeminal ganglia. Strand-specific 2.7-kilobase herpes simplex virus type 1 (HSV-1) ICP0 RNA probes were prepared, and their sense was determined in productively infected cells. Although in situ hybridization demonstrated ICP0 antisense RNA transcripts in the nuclei of neurons in 46% of the ganglia, ICP0 messenger RNA was not found in any of the ganglia. We conclude that HSV-1 antisense ICP0 RNA is present in humans during ganglionic latency.

Adult↗
PubMed1987

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.

Animals↗
PubMed1987

HSV-1 thymidine kinase negative vaccine: pathogenicity, protection, and perils.

Primary inoculation of mice and rabbits with an avirulent HSV-1 thymidine kinase negative (TK-) mutant reduced keratitis, mortality, and superinfection of the trigeminal ganglion (TG) as measured by cocultivation and iontophoresis-induced ocular shedding following ocular challenge with HSV-1 McKrae and W strains. However species differences were demonstrated; with complete protection in rabbits, and incomplete protection in mice. In mice, BUDR/autoradiography and restriction enzyme analysis identified both HSV-1 McKrae and W strains as having superinfected the TG, established latency and reactivated. Also, the avirulent TK negative inoculating strain was altered to a virulent TK positive strain through possible in vivo selection, mutation &/or host-modification, and possible in vivo recombination with the virulent challenge strains. We conclude that lower species differences require that potential HSV-1 vaccines be tested in non-human primates prior to clinical trials, and that a DNA-free subunit herpes vaccine represents a safer alternative to a live virus vaccine.

Animals↗
PubMed1987

2'-nor-cGMP, a new cyclic derivative of 2'NDG, inhibits HSV-1 replication in vitro and in the mouse keratitis model.

The present study examined the antiherpetic effect of 2'-nor-cGMP, a new cyclic phosphate derivative of 2'NDG, in vitro and in the mouse keratitis model. The 50% inhibitory dose (ID50) was determined with HSV-1 RE strain in Vero cell monolayers for 2'-nor-cGMP (6.9 mcg./ml), 2'NDG (.06 mcg/ml), and trifluridine (F3T) (.72 mcg/ml). Balb C mice underwent bilateral ocular inoculation with HSV-1 RE strain, and then were treated with different therapeutic regimens. The antiviral efficacy of each drug was evaluated by ocular virus titers, clinical grading of epithelial keratitis, and histological evaluation of stromal keratitis. 2'-nor-cGMP was the most effective drug (P = .0001) in reducing ocular viral titers. Both 2'-nor-cGMP and 2'NDG were significantly more effective (P = .0001) than F3T in reducing epithelial keratitis, and as effective as F3T in reducing stromal keratitis.

Acyclovir↗
PubMed1987

HSV-1 latency: thymidine kinase requirement and the round-trip theory.

The present study used the rabbit iontophoresis model to examine the thymidine kinase (TK) requirement for HSV-1 latency, and test the round trip theory of latency with emergent phenotypic mutations of the HSV-1 TK negative (TK-) inoculating strain. The results demonstrated repeated induced ocular shedding of latent HSV-1 in 14-100% of rabbits. The TK phenotype of recovered tear film following spontaneous shedding and repeated iontophoresis induction was thymidine kinase negative in 90% of eyes. Sequential shedding of TK- virus from the same eye over time was demonstrated in 21% of eyes in 33% of rabbits. We conclude that TK is not an absolute requirement for the establishment or reactivation of latent HSV-1 in the rabbit model. The round trip theory of latency was not supported as TK+ isolates and syncytial variants of the TK- inoculating strain which were recovered at the ocular surface after the initial iontophoresis could not be demonstrated following subsequent trials of iontophoresis.

Animals↗
PubMed1987

Timolol promotes reactivation of latent HSV-1 in the mouse iontophoresis model.

The present study examined the effect of topical timolol, a nonspecific beta 1 and beta 2 blocker on reactivation and ocular shedding of latent HSV-1 in an improved mouse iontophoresis model. Latent trigeminal ganglionic infection was established in Balb/C mice following inoculation by corneal scarification with HSV-1 W strain, a clinical isolate, and confirmed by co-cultivation. On day 30, postinfection (pi), the mice were divided into two groups, and treatment begun with coded eye drops (timolol 0.5% or placebo) BID OU for 5 days. On day 31 pi, iontophoresis with 1% 6-hydroxydopamine was performed, and daily treatment with topical epinephrine and 1% prednisolone was administered. Reactivation and recovery of latent HSV-1 was determined by daily ocular swabs, and characteristic HSV-1 cytopathic effect in Vero cells. Results demonstrated that the timolol-treated group had a significantly greater number of positive eyes, multiple shedding episodes, and total shedding days compared to the control group. We conclude that beta blockade promotes recurrent ocular shedding induced by epinephrine in the mouse iontophoresis latency model.

Animals↗