Protective Action of Specific Serum Against Experimental Vaccinia in Rabbits

Abstract

It is well established that in certain virus diseases such as poliomyelitis immune serum exercises little or no effect on the progress of the infection, even when administered in large doses several days before the usual onset of symptoms. 1 It is also of limited prophylactic value when administered before intranasal instillation with virus. 2 The therapeutic limitations of immune serum in virus diseases generally may be explained by the fact that cytotropic viruses once established within tissue cells are inaccessible to immune bodies in the plasma. Since viruses are primarily intracellular, rather than intercellular parasites, it would appear that the effectiveness of humoral antibodies is likely to be limited largely to infections in which the virus in transported to distant susceptible tissues by the blood stream, or tissue fluids. In diseases such as poliomyelitis, in which the virus is nerve-transmitted throughout and may gain admission to susceptible tissue without necessarily passing a barrier of immune plasma 3 the prospects of establishing significant protection against infection by the natural or intranasal route appear little better than those of gaining a therapeutic effect once infection is established. This is borne out by the observations already mentioned. 1 , 2 In this paper we deal with a virus (vaccinia∗) which although “neurotropic'does not, like poliomyelitis virus, depend on intact nerve paths for its transmission to susceptible cells, but may be disseminated by the blood stream and lead to generalized infection. More specifically, these studies are concerned with the protective action of immune serum in rabbits inoculated with vaccinia virus by the intranasal route.

Halva and Honl 4 40 years ago reported that serum from immune calves when injected subcutaneously into normal calves conveys some degree of protection against subsequent cutaneous inoculation with vaccinia virus.