Rescue Of Rainbow Trout (Oncorhynchus Mykiss) Gametes Compromised By Infectious Pancreatic Necrosis Virus (IPNV)     Philip E. McAllister   USGS/LSC, National Fish Health Research Laboratory, 11700 Leetown Road, Kearneysville, WV  25430     Pair mating is a management tool used to reduce the risk of gamete-associated generational transfer of infectious pancreatic necrosis virus (IPNV).  Fertilized eggs are segregated until the virus-carrier status of each parent is determined, and if either parent is found to carry IPNV, the egg lot is terminated.  This practice has resulted in the destruction of large numbers of potential progeny, diminishes genetic diversity, and can cause bio-political tension if threatened or endangered species or programmatic concerns are involved. We envisioned that gametes could be rescued based on the premise that gamete-associated transmission of IPNV is a variant form of horizontal transmission.  Using rainbow trout (Oncorhynchus mykiss) as a test species, we devised a simple processing procedure to reduce the initial virus burden of gametes, which are further treated with IPNV-specific antibody to neutralize residual virus.  In laboratory and operational trials, IPNV titers in gamete preparations were reduced from =106 PFU/ml to undetectable supporting the contention that IPNV may be associated with, but is not integral to, gamete composition.  Egg viability and sperm motility were preserved.  Hatch levels were comparable between treated and untreated lots of eggs.  IPNV infection has not been detected in progeny.