Genetic analysis of foot-and-mouth disease virus type O isolates responsible for field outbreaks in India between 1993 and 1999

Partial nucleotide sequence at the 3' end of 1D (VP1-encoding) gene of 90 f oot-and-mouth disease virus type O isolates recovered from field outbreaks in India between 1993-9 were determined. The sequences were compared with e ach other and reference viruses. The published sequences of 15 type O isola tes recovered from different parts of Asia and one isolate (O1BFS) from Eur ope and one from Egypt (O1/Sharquia/Egypt/72) were also included in the ana lysis for comparison. On the basis of phylogenetic analysis the viruses cou ld be grouped into four distinct genotypes (genotypes I-IV). All 90 isolate s from India were genotype-I, as were the reference isolates from Banglades h, China, Egypt, Iran, Saudi Arabia, Syria and Turkey. Genotype-I isolates were further subdivided into 16 sub-genotypes. The Indian isolates were fou nd to be extremely heterogeneous in nature and clustered into 12 different genetic groups. In genotype-I, the nucleotide sequence difference seen betw een the isolates was 0-11.6%, while among the Indian isolates it is 0-8.8%. Viruses of similar genetic groups are circulating in India, Bangladesh and countries of the Middle East. Genotype-II and -III are represented by isol ates from Lebanon(O1/South Lebanon) and Europe (O1-BFS), respectively. Geno type-IV is formed by isolates from China, Hong Kong and Taiwan. The present study reveals the occurrence of viruses belonging to multiple genetic grou ps over a short period of time and persistence of single genetic group in t he same geographical area over several years. This is consistent with the e ndemic nature of the disease in the country.