The use of lumpy skin disease virus genome termini for detection and phylogenetic analysis

Abstract

During 2006 and 2007 there were two outbreaks of lumpy skin disease (LSD) in Israel. An LSD virus (LSDV)-specific PCR assay was developed that can detected specifically LSDV even though the number of tested LSDV isolates were limited. Full-length sheep pox and LSDV genome sequences were aligned to find non-homologous regions, which were then used for preparing specific primers, whose specificity was tested against several LSDV DNA isolates and the system could detect all the different isolates. Specificity was tested with sheep pox, ORF and other DNA viruses such as bovine herpes 4: the primers did not support amplification of the expected-size fragments, therefore the system appears to be a valuable tool for detecting specifically LSDV. The newly developed system was activated at the first report of a possible disease outbreak. It confirmed the clinical picture, and was introduced subsequently into routine diagnosis. Phylogenetic analyses of a 466-bp fragment next to the genome ends showed that this system can distinguish between: sheep pox, goat pox and LSD, and the results revealed that the Israeli isolates from 2006 and 2007 are in the same clad and essentially identical to Ismaeliya 1989, Nigeria 1996, Senegal 1997, Cameroon 1996, the Kenya NI-2490 isolate, and the South African LD virulent isolate. In contrast the original 1958 LW Neethling vaccine appeared to be in a separate clad, suggesting that the South African attenuated LW vaccine developed from a different ancestral origin that the rest of the viruses tested suggesting that the South African attenuated LW vaccine developed from a different ancestral origin that the rest of the tested viruses or during the process of attenuating the virus by succession of egg inoculations.