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PROTECTION AGAINST WEST NILE VIRUS INDUCED BY A PREVIOUS INJECTION WITH DENGUE VIRUS

1971; Oxford University Press; Volume: 94; Issue: 6 Linguagem: Inglês

10.1093/oxfordjournals.aje.a121358

1476-6256

Winston H. Price, INDERJIT S. THIND,

Viral Infections and Outbreaks Research

Price, W. H. and I. S. Thind (Johns Hopkins Univ. School of Hygiene and Public Health, Baltimore, Md. 21205). Protection against West Nile virus induced by a previous injection with dengue virus. Amer J Epidem 94: 596–607, 1971.—The cross protection induced by a previous injection with dengue virus against West Nile virus was investigated in hamsters. It was found that hamsters were protected against West Nile virus if previously immunized with any of the four types of dengue virus. The challenge dose, the host, and the interval between immunization and challenge virus, influenced the degree of cross protection. The cross protection did not seem related to in vivo produced serum interferon or serum protective factor. The relationship of the protective effect to the in vivo production of serum neutralizing antibody was not definitively established. During the first several days after challenge with West Nile virus the brains of control hamsters showed a much higher virus titer than the challenge West Nile virus found in the brains of hamsters previously immunized with dengue 2 virus. By the 7th day post-challenge, however, the West Nile virus titer in the brains of the immunized hamsters was very similar to that found in the control hamster brains. The control hamsters showed more neuropathology (inflammatory response) in the brains due to West Nile virus than the dengue 2 immunized hamsters challenged with West Nile virus. There appeared to be two stages in the cross protection mechanism; one elicited by dengue virus, and the other induced by West Nile virus which was sensitive to cyclophosphamide. The data, as a whole, support the theory that the cross protection was due to a parameter of the immune response.