Lactic dehydrogenase virus.

Abstract

Inapparent virus infections of experimental animals and tissue culture systems present to the investigator a problem which it is impossible to overcome completely. Although all recognised viruses can be excluded from an experimental system, previously unsuspected viruses causing no obvious effects (‘silent’ viruses) will continue to be discovered. A truly silent virus would replicate, causing no change in its host cell, damage to infected tissue or immune response and would presumably be of no consequence. It is the relatively silent viruses which cause virtually no pathological changes but can alter the response of a test system, which are important. The lactic dehydrogenase virus (LDV) is an interesting example of such a virus. It causes no clinical disease in mice but can significantly alter their response to other infective agents and to the development of tumours. If the ideal virus is one which replicates rapidly and continuously without killing its host and is easily transmitted, LDV must be almost perfect. It replicates very rapidly in mice of all strains so far tested, produces a stable infection with a continuously high level of infective virus in the blood for the remainder of the animal’s life, yet causes no harm to its host. It lacks, however, one important property; the ability to pass readily from one animal to another under natural conditions. Infected females often fail to infect their young and transmission between adults is not very frequent. However, no doubt because of the permanence of the infected state, the virus survives in wild mice and is easily transmitted inadvertently by experimental procedures.KeywordsInfected MouseNewcastle Disease VirusGamma GlobulinUninfected MousePlasma EnzymeThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.