Vaccine for West Nile virus enters human clinical trials

By John Murphy, MDLinx
Published January 5, 2016

Key Takeaways

A new investigational vaccine designed to protect against West Nile virus infection, sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), has begun testing in a human clinical trial.

“Since first appearing in the United States in 1999, West Nile virus has emerged as an important health threat in this country. NIAID is committed to research efforts to advance a preventive vaccine that could protect people against West Nile Virus infection,” said NIAID Director Anthony S. Fauci, MD.

The experimental vaccine was discovered and developed by scientists at the Oregon National Primate Research Center at Oregon Health & Science University (OHSU) in Portland. The scientists were funded with a $7.2 million grant awarded in 2009 from NIAID, part of the National Institutes of Health. The new vaccine is being tested in a Phase 1 clinical trial at Duke University in Durham, N.C., one of NIAID’s Vaccine and Treatment Evaluation Units (VTEUs).

The OHSU research team, led by senior scientist Mark Slifka, PhD, created the investigational vaccine, HydroVax-001, with a novel, hydrogen peroxide-based process that renders the virus inactive while still maintaining key immune-system triggering surface structures. Because the virus used to make the vaccine is inactivated, the experimental vaccine likely could be used in a diverse population, including immunologically vulnerable groups, such as the elderly, NIAID said.

In preclinical studies, the test vaccine was effective at protecting mice against a lethal dose of West Nile virus. In mice, the vaccine elicited neutralizing antibody responses and CD8+ T cells, which bind to and kill infected cells.

The clinical trial will test the safety of the vaccine as well as its ability to produce an immune response. The trial will enroll 50 healthy men and women, ages 18 to 50 years. The volunteers will be randomly assigned to receive a low dose of the vaccine (1 mcg), a higher dose (4 mcg), or a placebo. Forty volunteers will receive the investigational vaccine; 10 study volunteers will receive the placebo. Each participant will receive an intramuscular injection twice: on day 1 and on day 29. Study participants will be followed for 14 months. Enrollment is expected to be completed by December 2015.

Additional information about the clinical trial is available at ClinicalTrials.gov using the identifier NCT02337868. For more information about NIAID’s West Nile Virus research, visit NIAID’s website.

About West Nile Virus

Most commonly spread through the bite of infected mosquitoes, West Nile virus (WNV) infection is typically a seasonal epidemic in the United States that begins in late spring or early summer and continues into the fall. Last year, 2,205 cases of WNV disease and 97 related deaths were reported in the U.S. Although an effective veterinary vaccine against WNV is available, no human vaccine has been approved for commercial use.

The majority of people infected with WNV show no symptoms. Roughly 1 in 5 people who are infected will display relatively mild symptoms, such as fever, headache, body aches, nausea, and vomiting. Only about 1 in 150 people infected with WNV will develop a serious neurologic illness, such as encephalitis or meningitis. Most people with WNV disease recover completely, but the elderly and other immunocompromised individuals are at higher risk for long-term side effects or death resulting from infection.

From 1999 to 2014, a total of 41,762 cases of WNV disease have been confirmed in the U.S., including 1,765 deaths.

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