SUMMARY: The antigens of eight strains of influenza virus were compared by a simple and economical complement-fixation technique in which drops on Perspex sheets replaced larger volumes of reagents in racks of tubes. By this means more extensive tests were made with a limited supply of material than by standard tube techniques.The specific antisera were prepared in mice, thus avoiding the elaborate isolation precautions necessary for ferrets, and sera from large groups were pooled to minimize individual variations between animals. The antigens were standardized in terms of the amount of complement fixed in the presence of excess homologous antiserum. The comparison of the strains is presented in the form of index numbers, ranging from 0 to 1.0; 1.0 represents complete identity of two strains, while the smaller numbers are taken to represent the degree of antigenic relationship between strains. Of the six strains examined which were isolated in different years, all were serologically distinct though the two I3 strains were closely similar and two of the A strains were fairly closely related. On the other hand, the three strains of influenza A virus isolated in 1947, two in London and one in the U.S.A., were identical.

Isolates of poxviruses were made from thirteen of eighteen specimens of scabs taken from pox lesions on buffaloes in five different districts of Maharashtra State, India, between December, 1985 and February, 1987. The biological characters of twelve of the isolates resembled those of the Hissar strain of buffalopox virus; the thirteenth isolate appeared to be vaccinia. The Hin dIII restriction profiles of DNA from all 13 isolates and from the Hissar strain were typical of those given by vaccinia strains. DNA from all twelve Maharashtra buffalopox (BPV) isolates gave identical profiles with each of three additional endonucleases; these viruses appear to be repeated isolations of a single strain of BPV. The DNA profile of this strain was not the same as that of the Hissar strain of BPV and both could readily be distinguished from each of the three strains of vaccinia virus which had been used in India. The thirteenth Maharashtra isolate was indistinguishable from vaccinia in its biological properties, but the restriction profile of its DNA differed from those of three vaccinia strains and the BPV isolates. These observations, made 6-8 years after cessation of smallpox vaccination indicate that BPV is an emerging enzootic virus and is a subspecies of vaccinia virus.

Cowpox soluble antigen is shown by gel-diffusion studies to contain at least nine precipitable substances whose presence is induced by virus infection. One of these substances, pattern component d, is not produced in white cowpox infections, and its production in vaccinia infection can be inferred only from the presence of small amounts of anti-d in anti-vaccinia sera.Comparison of cowpox with vaccinia has led to the recognition of a further line pattern component f which is readily demonstrated as a soluble precipitable substance in simple buffer extracts of vaccinia-infected tissue, but is demonstrated in extracts of cowpox-infected tissue only with difficulty; anti-f antibody is readily detected in antisera prepared against cowpox, white cowpox, and vaccinia.

Monkeypox mutants arising spontaneously or after serial, high multiplicity passage were characterized phenotypically and by restriction endonuclease mapping. Some resemble "whitepox" and variola viruses in several of the markers tested but all are distinguishable phenotypically from these. None resembles "whitepox" viruses in genome structure although near-terminal deletions or symmetrical, terminal rearrangements, relative to parental monkeypox, occurred. "Whitepox" viruses isolated from animals closely resemble variola in both phenotype and genome structure.

No abstract