Intensive West Nile Virus Circulation in Serbia in 2018-Results of Integrated Surveillance Program.

The results of the Serbian national integrated West Nile virus (WNV) surveillance program conducted in 2018 and funded by the Serbian Veterinary Directorate are presented. The WNV surveillance program encompassed the entire territory of Serbia and was conducted by the veterinary service in collaboration with entomologists and ornithologists. The objective of the program was early detection of WNV circulation in the environment and timely reporting to the public health service and local authorities to increase clinical and mosquito control preparedness. The program was based on the detection of WNV presence in wild birds (natural hosts) and mosquitoes (virus vectors) and on serological testing of sentinel horses (WNV-specific IgM antibodies). The season 2018 was confirmed to be the season of the most intensive WNV circulation with the highest number and severity of human cases in Serbia ever reported. The most intense WNV circulation was observed in the northern and central parts of Serbia including Vojvodina Province, the Belgrade City area, and surrounding districts, where most positive samples were detected among sentinel animals, mosquitoes and wild birds. The majority of human cases were preceded by the detection of WNV circulation during the surveillance. The WNV surveillance program in 2018 showed satisfactory results in the capacity to indicate the spatial distribution of the risk for humans and sensitivity to early detection of WNV circulation in the environment.

Importance of the lumpy skin disease virus (LSDV) LSDV126 gene in differential diagnosis and epidemiology and its possible involvement in attenuation.

Examination of lumpy skin disease virus (LSDV) isolates from different geographic regions and times revealed that assays developed in our laboratory for differentiating between virulent Israeli viruses and Neethling vaccine virus (NVV) are generally useful in most, if not all, endemic areas in which NVV-based vaccines are used. Recently it was revealed that the LSDV126 gene of field isolates contains a duplicated region of 27 bp (9 aa), while the vaccine viruses have only one copy. Phylogenetic analysis of a 532-bp segment carrying the LSDV126 gene and whole virus genome sequences revealed that LSDV isolates formed two groups: virulent and vaccine viruses. In this analysis, all of the capripox viruses that lack the ability to efficiently infect cattle were found to carry only one copy of the 27-bp fragment, suggesting that the LSDV126 gene plays an important role in the ability of capripox viruses to infect cattle. In silico analysis of potential antigenic sites in LSDV126 revealed that LSDV126 variants with only one copy of the repeat lack a potentially important antigenic epitope, supporting its possible significance in cattle infection. This study provides new information about the nature of the LSDV126 gene and its possible role in the life cycle of LSDV.

Methodology and results of integrated WNV surveillance programmes in Serbia.

Studies conducted during the past few years have confirmed active West Nile virus (WNV) circulation in Serbia. Based on these studies and the epidemiological situation, the Veterinary Directorate of the Ministry of Agriculture and Environmental Protection launched national WNV surveillance programmes in 2014 and 2015. The programmes encompassed the territory of Serbia and were conducted by the veterinary service in collaboration with entomologists and ornithologists. The objective of the programmes was early detection of WNV and timely reporting to the public health service and local authorities to increase both clinical and mosquito control preparedness. The WNV surveillance programmes were based on direct and indirect surveillance of the presence of WNV by the serological testing of initially seronegative sentinel horses and chickens as well as through viral detection in pooled mosquito and wild bird samples. The most intense WNV circulation was observed in all seven districts of Vojvodina Province (northern Serbia) and Belgrade City, where most of the positive samples were detected among sentinel animals, mosquitoes and wild birds. The West Nile virus surveillance programmes in 2014 and 2015 showed satisfactory results in their capacity to indicate the spatial distribution of the risk for humans and their sensitivity to early detect viral circulation at the enzootic level. Most of the human cases were preceded by the detection of WNV circulation as part of the surveillance programmes. According to the existing data, it can be reasonably assumed that WNV infection, now an endemic infection in Serbia, will continue to present a significant problem for the veterinary service and public health.