Vira

Seeing, however, that neither virus Ordinary, Tzaneen, nor Bulawayo protected completely against horse-sickness in the various parts of the Transvaal I now decided to make a combination of the two vira and to add to it the third virus, Bulawayo.

Source: wiktionary

Then the idea occurred to unite all these various vira and to obtain in this way a polyvalent virus which would protect against any of the vira of which it was composed, and by this means I hoped to reduce the mortality in practice.

Source: wiktionary

In order to settle the point whether an animal that had been immunised on this station would contract horse-sickness when subjected to either of the two vira, the following experiments were made:—[…]Our experiments not only demonstrate the fact that the immunity obtained from one virus does not completely protect against either of the other two, but that animals immune against two of the three vira may break down when subjected to the third virus.[…]The fact that polyvalent virus did not protect against all of the constituents, as it should have done, shows that in passing the polyvalent virus through a horse one or more of the vira must have been excluded from the mixture with which the horse was injected.[…]Accordingly, we again decided to increase the polyvalency of the virus by introducing into it, in addition to the strains with which we have inoculated hitherto, such other strains as have broken the immunity, and, in adding to the strain of polyvalent virus the new vira of relapses, we hope to finally arrive at a virus which will give immunity against any strain of the country.[…]The question may perhaps suggest itself whether an immunity of an animal can be increased by the repeated injection of different strains of vira at intervals, and the following table may prove interesting:—[…]

Source: wiktionary

The very obvious predominance of epidermal lesions in the gross pathological anatomy of variola and vaccinia, whether spontaneous or experimentally induced, has for many years been interpreted as indicating a peculiar affinity of these vira for skin and not merely for skin-tissue as a whole, but for that portion of it which is derived from epiblast.[…]Immunity to the vira in question was generally held to reside in the skin itself, and it is surprising that the demonstration by Sternberg (1892) of the fact that the serum of vaccinated animals acquired the property of neutralizing the specific virus in vitro so that a mixture of the two failed to take in a fresh animal, did so little to alter general opinion in the direction of postulating a general type of immunity, and that, too, although the presence of these viricidins or neutralizing bodies received ample confirmation from the work of Béclère, Chambon and Menard (1899) and many others.

Source: wiktionary