Serological and biochemical analysis of foot-and-mouth disease virus (serotype C3) isolated in Argentina between 1981 and 1986.
The evolution in the field is described for foot-and-mouth disease viruses belonging to serotype C3 in Argentina between 1981 and 1986. During 1981 and 1982 only three isolations of this serotype took place, which showed minor serological and biochemical variations from the prototype strain C3 Resende-Brasil/55. At the beginning of 1983 an outbreak was detected in a restricted geographical region caused by strains which had important serological and biochemical differences from the prototype strain. However, revaccination of the animals with the available commercial vaccine was sufficient to control the disease. During 1984 and up to 1986, a new outbreak of the same serotype took place in an extended geographical region of Argentina. During this outbreak, two field strains were isolated, studied and later included in the vaccine. One of them, strain C84, was a serological variant of the prototype strain and its inclusion in the vaccine had only a limited effect in controlling the disease. Inclusion of the other representative strain, C85, together with virus C84 finally reduced the number of outbreaks to the usual number reported.