Wild caught rock pigeons (Columba livia) with antibodies to West Nile virus were monitored for 15 months to determine antibody persistence and compare results of three serologic techniques. Antibodies persisted for the entire study as detected by epitope-blocking enzyme-linked immunosorbent assay and plaque reduction neutralization test. Maternal antibodies in squabs derived from seropositive birds persisted for an average of 27 days.West Nile virus (WNV) (Flaviviridae family, Flavivirus genus) is maintained in a bird-mosquito transmission cycle, and wild bird surveillance has proven effective in tracking the spread of this virus in North America. Since extensive avian mortality has been associated with WNV infection in North America, much of this surveillance has concentrated on deadbird testing (16). As demonstrated with other arboviruses, such as St. Louis encephalitis virus (SLEV), eastern equine encephalitis virus, and western equine encephalitis virus, serologic testing of birds represents another tool for further investigating WNV epidemiology (7,8,14).The duration of the antibody response, test performance, and persistence of maternal antibodies can complicate interpretation of serologic results. Information on the persistence of antibodies to WNV in avian species is currently limited. Experimentally, persistence of neutralizing antibodies to the North American strain of WNV in rock pigeons (Columba livia) was demonstrated over a 9-week period postinoculation and in chickens over a 28-day period postinoculation (9, 11). Pigeons inoculated with an African strain of WNV maintained antibodies for 16 months (12). Recaptured naturally infected wild birds in South Africa with initial WNV antibody titers of Ͼ40 lost demonstrable antibody by hemagglutination inhibition (HAI) in as few as 3 weeks (13).The objectives of this study were the following: (i) to determine the long-term persistence of antibodies to WNV in naturally infected rock pigeons, (ii) to compare the long-term utility of commonly used WNV serologic techniques (plaque reduction neutralization test [PRNT], HAI, and epitope-blocking enzyme-linked immunosorbent assay [ELISA]), and (iii) to determine the persistence of maternal antibodies to WNV in squabs derived from these naturally infected birds.Thirty rock pigeons, 20 seropositive for WNV and 10 negative controls, were captured in April 2003 in Atlanta, Georgia. All birds were banded and housed in a mosquito-free facility for 60 weeks. Venipuncture was performed on each bird upon entry and at 3-week intervals by wing vein. Serum samples were stored at Ϫ70°C.Using WNV (Georgia isolate DES-107-01) and SLEV (strain TBH-28), PRNTs were performed following standard protocols (1, 10). Titers were expressed as the reciprocal of serum dilutions reducing the number of plaques Ͼ90% (PRNT 90 ). Samples with PRNT 90 titers to WNV which were fourfold greater than titers to SLEV were considered seropositive for WNV. HAI assays were performed at the Florida Department of Health using a published protocol (5). Th...

Feral rock pigeons were screened for neutralizing antibodies to West Nile virus (WNV) during late winter/spring and summer of 2002 and 2003. Additionally, virus isolation from serum was attempted from 269 birds collected during peak transmission periods. The observed viremia levels and seroprevalence indicate that this species could be involved in amplifying WNV in urban settings.