Quantitative investigation of viral load in acute to subacute human adenovirus type 54 conjunctivitis

To understand the clinical course of human adenoviral (HAdV) conjunctivitis for establishing a better treatment regimen, thirty-eight eyes of 19 patients with HAdV-54 conjunctivitis for less than one week from onset were evaluated for clinical signs and symptoms and DNA copy numbers. It is observed that a viral load of 10⁴-10⁵ is required to develop symptoms of HAdV conjunctivitis, as symptoms were present in all the eyes whose viral load was ≥10⁴ at least once during the course. Next, it is observed that asymptomatic infections in contralateral eyes are common as the virus was detected in most eyes that did not develop conjunctivitis. Furthermore, there was no rapid decrease of the viral load in healed eyes, on the contrary, the viral load in healed eyes on day 15 was significantly higher than in unhealed eyes. This was likely due to corticosteroid instillation that rapidly alleviated symptoms but prolonged the duration of viral shedding. Recently, combination treatment with iodine and corticosteroids has been recommended for HAdV conjunctivitis. Assessing changes in viral load as well as clinical symptoms would be helpful to better understand the clinical course of this disease.

Cell Cycle-Dependent Kinase Cdk9 Is a Postexposure Drug Target against Human Adenoviruses

Human adenoviruses (HAdVs) infect respiratory, gastrointestinal, and urinary tracts and give rise to eye infections and epidemic keratoconjunctivitis (EKC). They persist in lymphoid tissue and cause morbidity and mortality in immunocompromised people. Treatments with significant postexposure efficacy are not available. Here, we report that inhibition of the cell cycle-dependent kinase 9 (Cdk9) by RNA interference, or the compound flavopiridol, blocked infections with HAdV-C2/5, EKC-causing HAdV-D8/37, and progeny formation in human corneal epithelial and cancer cells. Flavopiridol abrogated the production of the immediate early viral transactivating protein E1A without affecting nuclear import of viral DNA. In morphometric plaque assays, the compound exhibited antiviral efficacy in both pre- and postexposure regimens with therapeutic indexes exceeding 10. The study identifies Cdk9 as a postexposure drug target against adenovirus infections in vitro and suggests that the clinically tested anticancer drug flavopiridol is a candidate for treating adenoviral EKC or adenovirus emergence upon immune suppression.

Human adenovirus: Viral pathogen with increasing importance

The aim of this review is to describe the biology of human adenovirus (HAdV), the clinical and epidemiological characteristics of adenoviral epidemic keratoconjunctivitis and to present a practical update on its diagnosis, treatment, and prophylaxis. There are two well-defined adenoviral keratoconjunctivitis clinical syndromes: epidemic keratoconjunctivitis (EKC) and pharyngoconjunctival fever (PCF), which are caused by different HAdV serotypes. The exact incidence of adenoviral conjunctivitis is still poorly known. However, cases are more frequent during warmer months. The virus is endemic in the general population, and frequently causes severe disease in immunocompromised patients, especially the pediatric patients. Contagion is possible through direct contact or fomites, and the virus is extremely resistant to different physical and chemical agents. The clinical signs or symptoms of conjunctival infection are similar to any other conjunctivitis, with a higher incidence of pseudomembranes. In the cornea, adenoviral infection may lead to keratitis nummularis. Diagnosis is mainly clinical, but its etiology can be confirmed using cell cultures, antigen detection, polymerase chain reaction or immunochromatography. Multiple treatments have been tried for this disease, but none of them seem to be completely effective. Prevention is the most reliable and recommended strategy to control this contagious infection.