Potential link of single nucleotide polymorphisms to virulence of vaccine-associated field strains of lumpy skin disease virus in South Africa.

South Africa is endemic for lumpy skin disease and is therefore reliant on various live attenuated vaccines for the control and prevention of the disease. In recent years, widespread outbreaks of vaccine-like strains of lumpy skin disease virus (LSDV) were reported internationally, leading to an increase in the generation of full genome sequences from field isolates. In this study, the complete genomes of six LSDVs submitted during active outbreaks in the 1990s in South Africa were generated. Based on phylogenetic analysis, the six viruses clustered with vaccine strains in LSDV Subgroup 1.1 and are subsequently referred to as vaccine-associated. The genetic differences between the phenotypically distinct vaccine and vaccine-associated strains were 67 single nucleotide polymorphisms (SNPs). This study characterized the location and possible importance of each of these SNPs in their role during virulence and host specificity.

Lumpy skin disease of cattle: an emerging problem in the Sultanate of Oman.

Lumpy skin disease (LSD) is a highly infectious disease of cattle caused by a virus belonging to the Capripoxvirus genus of the family Poxviridae. The purpose of this study is to place on record the first confirmation of LSD in the Sultanate. The disease was diagnosed and confirmed using polymerase chain reaction, histopathology, transmission electron microscopy and serum neutralization testing. The epizootic occurred in 2009 involving a large number of animals and covering a wide area including Nezwa, Alqabel, Sohar, Saham and Burimi. Morbidity and mortality rates of 29.7 and 26.3 %, and 13.6 and 15.4 % were observed at Nezwa and Sohar, respectively. The clinical signs were much more severe in Holstein-Friesian cattle compared to indigenous breeds and were characterized by multiple skin nodules covering the neck, back, perineum, tail, limbs and genital organs. Affected animals also exhibited lameness, emaciation and cessation of milk production. Oedema of limbs and brisket, and superficial lymph node enlargement were highly prominent. It is not known from where the virus originated, or how it spread to the Sultanate. The disease has become endemic in the country and is liable to extend to other Gulf Cooperation Council Countries and cause a pandemic. It is of major concern to the Omani dairy industry. Due to the widespread presence of screw worm, serious economic losses can follow outbreaks.

Improved method for the generation and selection of homogeneous lumpy skin disease virus (SA-Neethling) recombinants.

Lumpy skin disease virus (LSDV) is being developed as a vector for recombinant vaccines against diseases of veterinary importance. A strategy for generating viral thymidine kinase (TK) gene-disrupted recombinants which are stable and homogeneous using the South African Neethling vaccine strain of LSDV as vector has been developed. To assist with the selection process, the Escherichia coli beta-galactosidase (lacZ) visual marker gene was incorporated into the constructs. However, the use of lacZ has certain limitations. An improved strategy was then devised substituting lacZ with the enhanced green fluorescent protein (EGFP) under control of the vaccinia virus (VV) P11K late promoter. The EGFP marker was found to enhance the selection process, and with the inclusion of additional sonication and filtration steps the number of passages required to select recombinants to homogeneity has been reduced. In support of the improved method for generation and selection of recombinants described, three different LSDV recombinants expressing the glycoprotein genes of bovine ephemeral fever virus, Rift Valley fever virus and rabies virus were prepared and characterised.