Ocular Adenoviral Infection:

Help May Soon Be On the Way

Is topical ganciclovir effective for the treatment of adenovirus conjunctivitis?

Jay S. Pepose, MD, PHD

Adenoviral conjunctivitis and keratoconjunctivitis are highly contagious conditions and a frequent source of community- and office-based epidemics worldwide. In the 1930s and 1940s, epidemics in naval shipyards in Hawaii and on the west coast exceeded 10,000 documented cases. The virus was so prevalent that in the 1930s it frequently was referred to as “shipyard eye.” It was renamed “epidemic keratoconjunctivitis” during World War II, where it frequently impacted industries associated with the war effort.

And adenoviruses are still a significant problem. They are the most common cause of ocular viral infection in many parts of the world^{1, 2} and the virus most frequently isolated from the conjunctiva.³ The impact of ocular adenoviral infection in adults and children is associated with significant morbidity, healthcare costs and socioeconomic loss due to absence from work or school. Help could be on the way, however. A topical antiviral drug currently in clinical trial, ganciclovir, could provide ophthalmologists with the first effective therapy for of adenoviruses.

Adenovirus Basics

Adenovirus is a non-enveloped, doublestranded DNA virus currently comprised of 53 serotypes. Infection with one serotype may not necessarily provide immunity to another. Epidemiological and molecular virology studies indicate that the adenovirus groups are continually recombining, changing and evolving over time.

Unlike many viruses that are enveloped and thereby more easily inactivated by disruption of the viral envelope (e.g., HSV, HIV), adenoviruses are quite resilient to disinfection and are long lasting in dessicated form for weeks on common fomites, such as towels, doorknobs, soap, instruments, eye drops and eyeglasses. The virus can also be spread by direct contact with ocular secretions, infectious virus on fingers, or via concurrent gastrointestinal infection.

The ocular infection generally begins unilaterally and often spreads to both eyes within two to seven days. It may cause epidemics and endemics, being most commonly spread in temperate climates in the summer (often associated with swimming pool use) or mid-winter (associated with respiratory infections). Epidemics are common in schools and the military, and have been spread in the offices of eyecare professionals via tonometers and other sources. Ocular viral shedding has been reported for up to 16 days.

Hand-to-eye and airborne droplet infection are also common means of transmission. Frequent hand washing and disinfection of fomites, tonometers and instruments and isolation from work or school may help to control transmission. Contact lens use should be discontinued and contact lenses, solutions and cases should be replaced after the infection has resolved. Recently, the US military has restarted oral vaccination against adenoviral serotypes 4 and 7 in an effort to limit respiratory spread in barracks and training facilities. However, currently no approved topical anti-adenoviral therapy exists.

Pertinent Clinical Syndromes and Features

Approximately one third of the 53 adenoviral serotypes have been isolated from cases of conjunctivitis. There are four major presentations of ocular adenovirus infection:

■ Follicular conjunctivitis (predominantly serotypes 1-11, 19).
■ Epidemic keratoconjunctivitis (EKC; predominantly serotypes 8, 19, 37, 53).
■ Acute hemorrhagic conjunctivitis (mostly serotypes 11, 19, 37).
■ Pharyngealconjunctival fever (mostly serotypes 3, 4, 7a, 11).

Patients may develop lid swelling, conjunctival injection, painful conjunctival membranes and palpable preauricular adenopathy. Associated findings include epiphora, photophobia, foreign-body sensation and small petechial hemorrhages in the palpebral and bulbar conjunctiva, along with follicular hypertrophy, hyperemia and edema (Figure 1). The corneal response to adenoviral infection following the onset of follicular conjunctivitis begins as a diffuse punctate keratitis, which then coalesce as focal epithelial keratitis, frequently associated with irritation, photophobia and epiphora. Subsequent immune reaction to intracorneal deposits of viral antigens result in subepithelial corneal infiltrates (Figure 2), which can cause light sensitivity, reduced vision and lead to irregular astigmatism. The differential diagnosis includes ocular herpes simplex, chlamydia and enterovirus infection.

Figure 1. Adenoviral conjunctivitis commonly presents with irritation, photophobia, lid swelling, follicular conjunctivitis and epiphora.

Figure 2. Focal keratitis is frequently followed 2-3 weeks later by corneal infiltrates, as shown in this slit beam. These findings can be associated with photophobia, decreased best corrected vision and irregular astigmatism.

Other etiologies besides adenovirus must be considered in the differential diagnosis of follicular conjunctivitis. It is important to appreciate that about 20% of acute follicular conjunctivitis is due to herpes simplex virus (HSV). HSV conjunctivitis is less likely to have accompanying lymphadenopathy, conjunctival scarring or pseudomembranes than adenoviral conjunctivitis. Corneal lesions with HSV generally occur earlier in onset than with adenovirus. Unlike adenoviral ocular disease, there is no seasonal component. HSV may have accompanying orofacial or lid vesicles, especially in atopics. Even if HSV keratoconjunctivitis is misdiagnosed as adenovirus, HSV is generally responsive to topical ganciclovir. This may represent a potential advantage if these studies demonstrate clinical anti-adenoviral efficacy.

Rationale for a Clinical Study

Sufficient supporting laboratory and clinical data exist to warrant a clinical trial of topical ganciclovir for the treatment of adenoviral keratoconjunctivitis. For example, several studies has shown that ganciclovir (GCV) is active in vitro against adenovirus.^4,5 Animal studies in the cotton rat also have shown some efficacy.⁶ In addition, Tabbara⁷ performed a controlled, randomized, double-masked clinical study of patients with adenovirus keratoconjunctivitis and found that ganciclovir significantly reduced both the duration of disease and the incidence of subepithelial infiltrates. In this masked study of 18 patients, 0.15% ganciclovir gel was compared to preservative-free artificial tears as a placebo. He found the mean time of adenovirus recovery was significantly shorter for ganciclovir-treated patients at 7.7 days in contrast to 18.5 days for those who received artificial tears (P < 0.05). In addition, subepithelial opacities developed in 7 (77%) patients treated with artificial tears, compared to 2 (22%) patients in the GCV-treated group.

Objectives of the Zirgan Clinical Trial

The purpose of the study is to evaluate the safety and efficacy of 0.15% ganciclovir gel (Zirgan, Bausch + Lomb) in patients with adenoviral keratoconjunctivitis in comparison with 0.3% hypromellose gel (Genteal gel, Novartis) as placebo. The primary outcome of the study is to determine whether topical 0.15% ganciclovir gel alone will reduce the duration of viral shedding from the ocular surface, as determined by quantitative viral isolation in A549 cell tissue culture, compared to placebo 0.3% hypromellose gel.

The secondary outcomes of the study are whether topical 0.15% ganciclovir will reduce the incidence and severity of second eye involvement, lower the incidence and severity of subepithelial infiltrates, reduce the secondary spread to family members, friends, classmates or co-workers (especially since the virus is very stable at room temperature and can last for days on fomites, such as towels, doorknobs, etc.), reduce the degree of bulbar conjunctival injection, reduce ocular discomfort, and be considered an effective treatment by the patient.

Because we want to test the antiviral effects of ganciclovir against adenovirus replication and shedding, the study is designed to capture patients early in the course of disease before the viral load is naturally declining. The inclusion criteria for the study is the presence of follicular conjunctivitis of 72-hour duration or less who test positive on the Rapid Pathogen Screening Adeno Detector Plus Immunoassay (RPS) for adenoviral antigens, which is described later. In an effort to exclude other forms of conjunctivitis, patients with a mucopurulent discharge, history of herpes simplex viral conjunctivitis, or allergic conjunctivitis are not eligible. Ten US and two international sites are participating.

New Tool for Adenoviral Conjunctivitis

Clinical studies of conjunctivitis with laboratory confirmation indicate that it's often difficult to differentiate bacterial from viral forms of acute conjunctivitis by relying on signs or symptoms or both.⁸ In past studies, corneal and external disease specialists' clinical diagnosis of adenoviral conjunctivitis had laboratory confirmation in only 20-25% of cases. For that reason, this study utilizes a rapid immunoassay applied to conjunctival scrapings (Figure 3) that can be performed in the examining lane and quickly and easily processed by a technician.

Figure 3. Conjunctival scrapings can be processed for adenoviral antigens in approximately 10 minutes using the RPS Adeno Detector Plus immunoassay for in-office detection.

The RPS Adeno Detector Plus is a point-of-care immunoassay that has 93% sensitivity and 96% specificity. It takes approximately 10 minutes to perform. The monoclonal antibodies used in the assay detect all 53 adenoviral serotypes. The device has a self-contained element used for conjunctival scraping and a colorimetric binary readout similar to urine pregnancy tests. This assay is FDA 510(k) cleared, CLIA-waived and commercially available. It has a unique Medicare procedural CPT code, 87809qw, which more than covers the cost of the test kit.

Dual Cause of EKC Pathogenesis

The pathogenesis of adenoviral keratoconjunctivitis comprises an early phase of viral replication, followed by host immune reaction (e.g., subepithelial corneal infiltrates, symblepharon), which can have significant sight-threatening and structural consequences. In some animal studies,^{9, 10} the use of topical steroid alone resulted in prolonged adenoviral shedding, suggesting cautious, judicious use of topical steroids without antiviral coverage. While immunity plays an important role in limiting the duration of adenoviral conjunctivitis and often leads to lesser involvement in the second eye affected, exuberant immune responses can result in formation of membranes or pseudomembranes, permanent scarring and corneal subepithelial infiltrates causing a loss of one or more lines of best-corrected vision.

If these findings are observed in the study, the ophthalmologist has the discretion of adding topical 0.5% loteprednol etabonate suspension (Lotemax; Bausch + Lomb) q.i.d. to the study medication, with tapering as per clinical course at the doctor's discretion, to serve as a rescue medication and reduced the inflammatory response. Some patients may require very gradual tapering of the topical corticosteroid to avoid a rebound of signs and symptoms.

Other antiviral studies that are ongoing include a new formulation of 0.4% povidone-iodine/0.1% dexamethasone, which has proven efficacious in a rabbit model of adenoviral keratoconjunctivitis.¹¹ It will be interesting to determine whether the antiseptic action of this compound will inactivate only extracellular adenovirus or also intracellular forms of adenovirus, both of which may be important and necessary in controlling the life cycle of viral replication.

Ganciclovir Treatment Goals

If proven effective, the goals of topical ganciclovir treatment include limiting the development of corneal infiltrates (which can result in irregular astigmatism, glare, photophobia and hyperopic shifts), the duration of adenoviral shedding, and spread to the second eye. Additional goals are to prevent the spread of disease by early and accurate diagnosis and treatment, to reduce the cost of lost days at work and school, to afford specific antiviral treatment and avoid the over-prescription of unnecessary, ineffective antibiotics. Finally, accurate diagnosis and appropriate antiviral rather than antibacterial therapy should reduce the costs of treatment and diminish the development of antibiotic associated allergies and toxicities. OM

References

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2. Waka Saitoh-Inagawa W, Aoiki K, Uchio E, Itoh N, Ohno S. Ten years' surveillance of viral conjunctivitis in Sapporo, Japan. Graefe's Arch Clin Exper Ophthalmol. 1999; 237:35-8.
3. Marangon FB, Miller D, Alfonso E. Laboratory results in ocular viral diseases: Implications in clinical-laboratory correlation. Arq Bras Oftalmol. 2007;70: 189-194.
4. Naesens L, Lenaerts L,Andrei G,et al. Antiadenovirus activities of several classes of nucleoside and nucleotide analogues. Antimicrobial Agents Chemotherapy. 2005, 49: 1010-1016.
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6. Trousdale MD, Goldschmidt PL, Nóbrega R. Activity of ganciclovir against human adenovirus type-5 infection in cell culture and cotton rat eyes. Cornea. 1994;13:435-439.
7. Tabbara K, Jarade E. Ganciclovir effects in adenoviral keratoconjunctivitis. 2001; ARVO abstract 3111 (suppl); S579.
8. Rietveld RP, van Weert HC, ter Riet G, Bindels PJ. Diagnostic impact of signs and symptoms in acute infectious conjunctivitis: systematic literature search. BMJ.2003; 327:789.
9. Romanowski EG, Yates KA, Gordon YJ. Topical corticosteroids of limited potency promote adenovirus replication in the Ad5/NZW rabbit ocular model. Cornea. 2002; 21:289-291.
10. Romanowski EG, Yates KA, Gordon YJ. Short-term treatment with a potent topical corticosteroid on an acute ocular adenoviral infection in the New Zealand white rabbit. Cornea. 2001;20:657-60.
11. Clement C, Capriotti JA, Kumar M, et al. Clinical and antiviral efficacy of an ophthalmic formulation of dexamethasone povidone-iodine in a rabbit model of adenoviral keratoconjunctivitis. Invest Ophthalmol Vis Sci. 2011:52:339-44.

Dr. Pepose is Director of Pepose Vision Institute and professor of clinical ophthalmology at Washington University School of Medicine, St. Louis. He is a consultant to Bausch + Lomb.