Preparation of Antigens 561; Preparation of Sera 567; Preparation of Erythrocytes 568; Chemical Reagents 569; Technique of HA and HI Tests 570; HA Titrations 571; HI Tests 572; References 573

During the past few years, the methods for conducting hemagglutination (HA) and hemagglutination-inhibition (HI) tests with arthropod-borne (arbor) viruses have undergone a number of modifications, directed toward simplification and improvement as well as extension of the tests to include a larger number of arbor viruses. Accordingly, it seems desirable at this time to bring together, in one publication rather than in a series of papers, a description of the procedures currently in use in The Rockefeller Foundation Virus Laboratories. Some of the procedures were initially developed elsewhere; of those developed in this laboratory, most aspects have not been previously reported.

It was stated by Hallauer (1946) that he had obtained a hemagglutinating antigen from viscerotropic but not from neurotropic strains of yellow fever.