Tissue tropism and neuroinvasion of West Nile virus do not differ for two mouse strains with different survival rates

West Nile virus (WNV) is a mosquito-borne flavivirus that infects the central nervous system of humans and other animals. In this study, we found that C3H/HeN (M) mice exhibited a higher morbidity and mortality than C57BL/6 (B6) mice. We compared tissue tropism, viral replication and kinetics for C3H and B6 mice during acute viral infection. WNV was detected in multiple tissues, including novel sites such as the skin, duodenum and pancreas, but the tropism was identical for the two strains. Additionally, viral load and kinetics of spread did not differ substantially between strains. Neuroinvasion occurred in both strains by day 3 post-inoculation with early detection in the olfactory bulbs and spinal cord, suggesting that WNV neuroinvades at specific sites. Furthermore, neuroinvasion and viral load in the CNS did not predict disease outcome. Our data suggest that the disparities in morbidity and mortality between C3H and 136 mice are not due to differences in tropism, viral load or kinetics during acute WNV infection. (c) 2007 Elsevier Inc. All rights reserved.