Arch Virol (2005) 150: 1249–1256
Experimental infection of pigs with West Nile virus
M. L. Teehee
, M. L. Bunning
, S. Stevens
, and R. A. Bowen
Departments of Microbiology, Immunology and Pathology,
Colorado State University, Fort Collins, Colorado, U.S.A.
Department of Biomedical Sciences, Colorado State University, Fort Collins,
United States Air Force, Ofﬁce of Surgeon General, Bolling Air Force Base,
Washington, DC, U.S.A.
Centers for Disease Control and Prevention, Fort Collins, Colorado, U.S.A.
Received August 20, 2004; accepted November 30, 2004
Published online March 17, 2005
Summary. Young adult and weanling pigs were challenged with the NewYork 99
strain of West Nile virus through the bite of infected mosquitoes. Each of six adult
pigs seroconverted, but virus was isolated from serum of only one pig following
challenge. Three of ﬁve weanling pigs developed viremia, with peak titers of 10
PFU/mL. Clinical signs attributable to West Nile virus infection were
not observed in any of these animals. An additional four pigs were challenged by
feeding West Nile virus-infected mice, and none of the four developed a detectable
viremia or seroconverted. These results suggest that pigs are unlikely to play a
signiﬁcant role as amplifying hosts of West Nile virus.
West Nile virus (WNV), an arthropod-borne virus, is a member of the antigenic
complex of ﬂaviviruses that include Japanese encephalitis, Kunjin, Murray Valley
encephalitis and St. Louis encephalitis viruses . WNV was ﬁrst described in
Uganda in 1937 , and since then, has been isolated from humans, birds and
mosquitoes throughout Africa, and in regions of Middle East, Europe and Asia
[8, 12, 24]. WNV was ﬁrst recognized in the Western hemisphere in 1999 in New
York as the virus responsible for outbreaks of viral encephalitis among several
species of birds, and of fatal encephalomyelitis in humans and horses [4, 14].
Subsequently, WNV has spread widely through North America, where it is now
considered endemic [6, 17].
WNV is a well known pathogen of humans, horses and many species of birds
[2, 3, 12, 13, 16, 22, 25], but little work has been conducted to characterize