# Presentation: 837780

## Equine West Nile Virus Vaccine

- Mary Beth Evans, M.S., D.V.M.
- Senior Staff Veterinarian
- Licensing and Policy Development
- Center for Veterinary Biologics
- USDA, APHIS, Veterinary Services
- Ames, Iowa

## West Nile Virus Vaccine, Killed Virus

- Indications: For use in healthy horses as an aid in the prevention of disease of WNV.
- Administration:  1 mL intramuscularly, second dose 3 to 6 wks. after the first dose.
- USDA issued Conditional license August, 2001 - Ft. Dodge Animal Health, Inc.

## Requirements for Conditional License, Title 9, Code of Federal Regulations, Part 102.6

- to meet an emergency condition
- limited market, local situation or other special    circumstance
- an expedited procedure
- 		- assures purity and safety
- 		- reasonable expectation of efficacy

## Conditional License Requirements

- Preparation is limited to a predetermined time period, usually 1 year, which is specified at the time of issuance
- Prior to termination, licensee may request reissuance
- Reissuance is considered if licensee has demonstrated acceptable progress toward completion of host animal efficacy and potency test studies.
- After consideration, Administrator will either reissue license or allow it to terminate.

## Conditional License Requirements

- Distribution in each State is limited to authorized recipients designated by proper State officials under such additional conditions as these authorities may require.
- All labels will contain a statement that the product license is conditional and that efficacy and potency studies are in progress.
- Trade names for the product may not be used.

## FDAH WNV Vaccine, Killed Virus

- NVSL equine isolate
- Satisfactory completion of purity and laboratory/field safety testing
- “Reasonable” expectation of efficacy based on host animal serology results
- USDA confirms purity results, inactivation testing, and laboratory safety results.
- USDA accepts field safety data as sufficient to issue conditional license.

## Field Safety Trials

- Vaccine administered according to label directions (2 doses IM, 3 - 6 wks. Apart) under field conditions.
- Two serials of product were used in eight states, 10 trial sites  --> approx. 650 horses vaccinated.
- Due to emergency situation (FL), preliminary field safety data for 197 horses was submitted to USDA to justify issuance of conditional license and approved.
- Post licensure the completed FST results were approved by USDA.

## FST Horses - Serology Results

- Plaque reduction neutralization testing was performed (PRNT) on at least 20% of all participating horses.
- PRNT of a sample reported as highest dilution that achieves at least 90% plaque reduction.
- Vaccination with 2 doses elicited an antibody response of neutralizing antibody titer of greater than or equal to 5 (range 5 - 1280) at approx. 2-3 wks. post second vaccination.
- Vaccinated horses do not develop an IgM response after either the 1st or 2nd dose; only IgG response has been detected.

## Firm Studies in Progress

- Challenge model has been developed
- Completed first efficacy trial --> preliminary results look favorable.
- Working on adding WNV to large combination vaccine.

## Adverse Reports

- CVB has had no reports of any adverse events regarding the WNV Vaccine, Killed Virus product.