Antigenic and genetic characterisation of foot-and-mouth disease type O viruses from the Far East

Introduction Foot-and-mouth disease (FMD) is a highly contagious viral vesicular disease of cloven-hoofed animals. It has occurred in most parts of the world and is endemic in sub-Saharan Africa, southern Asia, the Middle East and parts of South America. North and Central America, the Caribbean, Australia and New Zealand are free from the disease. Western Europe and North Africa although normally free from disease have sporadic outbreaks. FMD is endemic in many parts of the Far East, including Myanmar, Thailand, Laos, Cambodia and Vietnam. Malaysia was free until recently when in 1990 outbreaks of Asia 1 occurred near to the border with Thailand. During the period 1992-1998 outbreaks have been caused by types O, A and Asia 1. In March 1997 Taiwan province of China reported three outbreaks of FMD to the Office International des Epizooties. Subsequently, the OIE/FAO World Reference Laboratory for FMD (WRLFMD) at Pirbright, confirmed that FMDV serotype O had been isolated from samples that had been submitted. Molecular analysis of the samples identified them as belonging to a group of viruses which were distinct to Hong Kong and the Phillippines and which were almost certainly related to strains presumed to be present in China. Despite zoo-sanitary measures and the slaughter of diseased and in-contact animals the disease rapidly spread to most parts of the island. This was the first reported case of FMDV in Taiwan province of China since the 1930's. Relatively little is known about the antigenic characteristics of viruses of serotype O from the Far East. This paper examines the relationship between recent isolates of type O FMDV from the Far East using the results of deduced amino acid sequences from nucleotide sequence data, liquid phase blocking enzyme linked immunosorbent assays (LPB-ELISA) and antigenic profiling ELISA data using panels of MAbs elicited against distinct genetic FMD viruses of serotype O (O1/Kaufbeuren/FRG/66 and O1/Manisa/Turkey/69).