Vaccines may have future in ocular HZV and HPV

Chicago-Vaccines may have a role in corneal and external ocular disease, specifically herpes zoster virus (HZV) and human papilloma virus (HPV) infections, because of the successes of the vaccines in preventing systemic diseases, according to Minas T. Coroneo, MD, who discussed the vaccines during cornea day at the annual meeting of the American Society of Cataract and Refractive Surgery.

"HZV and HPV are highly prevalent in the United States and are associated with high morbidity and cost," said Dr. Coroneo, chairman, Department of Ophthalmology, University of New South Wales, Sydney, Australia. "Ophthalmologists have almost been bystanders in the development of vaccines for these viruses."

The Shingles Prevention Study found that a vaccine reduces the incidence of post-herpetic neuralgia, the impact of which is very high in elderly patients. There is a 10% to 25% chance of getting HZV infection during an individual's lifetime, and the associated complications, such as loss of sight, are substantial. Incidence of infection increases with age.

Ophthalmologists, Dr. Coroneo said, should be interested in preventing post-herpetic neuralgia because cranial dermatomes are the second most commonly affected site following thoracic infections and because of the potential for loss of sight. In addition, the length of time of the attacks is greater in older patients.

The rationale for a strategy to prevent shingles is important because available treatments do not prevent post-herpetic neuralgia that when left untreated is associated with further complications. Vaccines have been available and in clinical trials have successfully reduced the incidence of HZV infection and post-herpetic neuralgia for up to 5 years after vaccination.

"The vaccine works because of the induction of specific memory T cells that normally decrease in number with aging," Dr. Coroneo said.

In May 2006, the FDA licensed a live zoster vaccine (Zostavax, Merck) (26 mg) to prevent HZV infection in patients older than 60 years. The drug, which costs about $150 per dose in the United States and twice that in Australia, is associated with side effects of headache and injection site reactions.

HPV infection

Another infectious disease that has received a great deal of attention is HPV, because it is the most common sexually transmitted infection. In 2006, the FDA approved HPV quadrivalent (Gardasil, Merck) to prevent cervical cancer, the second-leading type of cancer in women, and precancerous genital lesions and warts resulting from HPV types 6, 11, 16, and 18-the last two being the worst. An HPV vaccine (Cervarix, GlaxoSmithKline) was approved in 2007 to prevent HPV infection, especially types 16 and 18. Both vaccines are extremely effective, according to Dr. Coroneo.

Eighty percent of sexually active individuals will be exposed to HPV during their lifetime, Dr. Coroneo said. The virus invades epithelial stem and basal cells and evades the immune system by proliferating in the superficial layers of the cervix, skin, and conjunctiva. Twenty million individuals in the United States are estimated to be infected with HPV at a high cost to their communities.

The aim of the vaccine is to reduce cervical, vulvar, and vaginal cancers, but it is unknown what effect a vaccine against HPV would have in the eye. However, the vaccine might be effective in some head and neck cancers.

Patients with corneal grafts are potentially at very low risk of rejection after vaccination.

"The presence of HPV in the eye is controversial," Dr. Coroneo said. The virus has already been documented in the eye. The results of four studies suggested that there may be respirable virus particles in excimer laser plumes as the result of genital warts, which are highly prevalent.

A vaccine for herpes simplex virus is not expected to be available soon, but vaccines may become available against Pseudomonas aeruginosa and Acanthamoeba.