[New medical treatment for viral conjunctivitis].

Around one million people in Japan are suffering from adenoviral conjunctivitis every year and it is recognized as one of the major pathogens of nosocomial infection. Several complications, such as corneal erosion and conjunctival pseudomembrane, are observed in some of the cases and corneal sube- pithelial opacity may bring visual impairment. Moreover, no specific anti-adenoviral agent has been discovered and an effective treatment has not been established for adenoviral infection. We have researched new medical treatment for viral conjunctivitis based on recent findings in adenoviral conjunctivitis. Firstly, anti-adenoviral activity was evaluated in vitro in agents which could possibly act as anti-adenoviral drugs. Twelve candidates, such as zalcitabin, interferon beta, etc., were selected among antiviral drugs, adenoviral receptor inhibitors, natural products and anti-inflammatory drugs. Remarkable anti-adenoviral effect was observed in zalcitabin, sanilbudine, interferon beta and anti-osteopontin peptide. Two anti-human immunodeficiency virus (HIV) drugs with anti-adenoviral activity, zalcitabin and sanilbudine, are nucleoside reverse transcriptase inhibitors, but, in contrast, non-nucleoside reverse transcriptase inhibitors and protease inhibitors were ineffective against adenovirus. Interferon beta and anti-osteopontin peptide displayed anti-adenoviral effects by absorption inhibition. Secondly, side effects caused by possible anti-adenoviral eye drops, including cidofovir whose development as eye drops against eyeball and ocular adnexa had been suspended, were analyzed in a white rabbit model. In animals given cidofovir locally, significant narrowing of lacrimal canaliculus, redness of eyelid and conjunctival injection was observed, but obstruction of the lacrimal duct was not found. Although zalcitabin and sanilbudine eye drops induced eyelid redness, no change was observed in the lacrimal route and conjunctiva. In animals treated by cidofovir, inflammation histologically suggesting mainly allergic change was observed. These results indicate that these four drugs are possible candidate for safe eye drops against adenoviral conjunctivitis. These four agents are divided into two categories, inhibitors of adenoviral replication, zalcitabin and sanilbudine; and suppressors of adenoviral infection, interferon beta and anti-osteopontin peptide. It is expected that eye drops for specific treatment of adenoviral conjunctivitis are going to be available in the near future following investigation of therapeutic effect in adenoviral infected animals and clinical trials in humans.