The In Vivo Differentiation of Strains of Yellow Fever Virus in Mice

Abstract

Strains of yellow fever virus isolated since 1927 in Africa and the Americas, and strains derived from them, were differentiated by the responses of mice of different ages to i.p. or intracerebral (i.c.) infection. Infection, antibody conversion, protection and death were presented on age-dose response phase diagrams that serve as in vivo fingerprints for the differentiation of virus strains and their modifications through passage and selection. Correlations between marker characteristics are discussed in terms of the efficiency of infection, regulatory (pre-challenge) and protective (post-challenge) immunity, and the expression of virulence. The requirement in virus strain specification for the resolution of events on pathogenic and immunogenic pathways is discussed.