PASSIVE TRANSFER OF ACQUIRED RESISTANCE IN MICE TO GROUP B ARBOVIRUSES BY SERUM PROTECTIVE FACTOR(S) (SPF) INDEPENDENT OF SERUM NEUTRALIZING ANTIBODY OR INTERFERON

Thind, I. S. and W. H. Price (Schl. of Hygiene, The Johns Hopkins Univ., Baltimore, Md. 21205). Passive transfer of acquired resistance in mice to group B arbo-viruses by serum protective factor(s) (SPF) independent of serum neutralizing antibody or interferon. Amer. J. Epid., 1968, 88: 287-300.-Cross-protection between group B arboviruses cannot be directly related to the detectable serum neutralizing antibody or serum interferon levels at the time of challenge or subsequent to it. Cross-protection of similar magnitude is also found when cyclophos-phamide, a potent immunosuppressant drug, is used both at the time of immunization and challenge. Such cross-protection has been related to another humoral factor called Serum Protective Factor (SPF). Some properties and the possible mechanism of action of SPF are outlined in this paper. SPF can be passively transferred and appears to play a dominant role in cross-protection. On primary infection, cyclophosphamide markedly increases the lethal titer of the parent strain of Langat virus, and also increases the titer of the vaccine strain, but to a lesser extent. © 1968, by The Johns Hopkins University.