Estimating the Basic Reproductive Number for African Swine Fever Using the Ukrainian Historical Epidemic of 1977.

In 1977, Ukraine experienced a local epidemic of African swine fever (ASF) in the Odessa region. A total of 20 settlements were affected during the course of the epidemic, including both large farms and backyard households. Thanks to timely interventions, the virus circulation was successfully eradicated within 6 months, leading to no additional outbreaks. Detailed report of the outbreak's investigation has been publically available from 2014. The report contains some quantitative data that allow studying the ASF-spread dynamics in the course of the epidemic. In our study, we used this historical epidemic to estimate the basic reproductive number of the ASF virus both within and between farms. The basic reproductive number (R0 ) represents the average number of secondary infections caused by one infectious unit during its infectious period in a susceptible population. Calculations were made under assumption of an exponential initial growth by fitting the approximating curve to the initial segments of the epidemic curves. The R0 both within farm and between farms was estimated at 7.46 (95% confidence interval: 5.68-9.21) and 1.65 (1.42-1.88), respectively. Corresponding daily transmission rates were estimated at 1.07 (0.81-1.32) and 0.09 (0.07-0.10). These estimations based on historical data are consistent with those using data generated by the recent epidemic currently affecting eastern Europe. Such results contribute to the published knowledge on the ASF transmission dynamics under natural conditions and could be used to model and predict the spread of ASF in affected and non-affected regions and to evaluate the effectiveness of different control measures.

Spatio-temporal modeling of the African swine fever epidemic in the Russian Federation, 2007-2012.

In 2007 African swine fever (ASF) entered Georgia and in the same year the disease entered the Russian Federation. From 2007 to 2012 ASF spread throughout the southern region of the Russian Federation. At the same time several cases of ASF were detected in the central and northern regions of the Russian Federation, forming a northern cluster of outbreaks in 2011. This northern cluster is of concern because of its proximity to mainland Europe. The aim of this study was to use details of recorded ASF outbreaks and human and swine population details to estimate the spatial distribution of ASF risk in the southern region of the European part of the Russian Federation. Our model of ASF risk was comprised of two components. The first was an estimate of ASF suitability scores calculated using maximum entropy methods. The second was an estimate of ASF risk as a function of Euclidean distance from index cases. An exponential distribution fitted to a frequency histogram of the Euclidean distance between consecutive ASF cases had a mean value of 156 km, a distance greater than the surveillance zone radius of 100-150 km stated in the ASF control regulations for the Russian Federation. We show that the spatial and temporal risk of ASF expansion is related to the suitability of the area of potential expansion, which is in turn a function of socio-economic and geographic variables. We propose that the methodology presented in this paper provides a useful tool to optimize surveillance for ASF in affected areas.

Cartographical analysis of African swine fever outbreaks in the territory of the Russian Federation and computer modeling of the basic reproduction ratio.

African swine fever (ASF), have been introduced into the Russian Federation from Transcaucasia countries, has spread widely across the territory of the southern region of Russia since 2008. In this work we present an analysis of the spatial and temporal spread of the disease, determine risk factors by means of GIS tools and model the dynamics of the epidemic process both within infected premises (farms) and at the between-farm level to estimate the basic reproduction ratio R(0). The analysis allowed us to make a conclusion about the anthropogenic nature of the risk factors for disease spread. The major significant risk factors identified were: density of the road network, density of domestic swine population and density of water bodies in the study area. The basic reproduction ratio was estimated to range from 2 to 3 at the between-farm level and from 8 to 11 within the infected farms. These initial studies of the ASF epidemic provide information on which to based control and prevention programs.

[Synthesis and immunogenic properties of peptides--fragments of the immunodominant regions of the VP1 protein of the Asia-1 type of foot- and-mouth disease virus]. / Sintez i immunogennye svoistva peptidov--fragmentov immunodominantnykh raionov belka VP1 virusa iashchura tipa Aziia-1.

Potential immunodominant epitopes were predicted on the basis of a theoretical analysis of the antigenic structure of the VP1 protein of the type Asia-1 foot-and-mouth disease virus. Peptides corresponding to the 140-153, 136-153, 132-153, 143-157, 137-157, and 193-208 fragments of the VP1 protein sequence were synthesized by the solid phase method, and the immunogenic properties of the peptides were studied on guinea pigs. The shortest peptide exhibiting the protective effect was found to correspond to the, 140-153 fragment of the VP1 sequence. The Plm-(Gly)3-(140-153)-(Gly)2-Lys(Plm)-Leu and [Ac-(140-153)-(Gly)3]8-(Lys)7-Gly synthetic constructions in combination with adjuvants provided up to 80% protection of immunized animals against infection with the foot-and-mouth disease virus.

[Primary structure of the 3'-terminal region of the RNA-polymerase gene in foot-and-mouth virus A22]. / Pervichnaia struktura 3'-kontsevoi oblasti gena RNK-polimerazy virusa iashchura A22.

This study was undertaken for the purpose of determining the primary structure of the 3' end gene of RNA polymerase of foot-and-mouth disease virus A22 550. Reported are isolation and purification of the virus, isolation of RNA, synthesis of cDNA, experience obtained from cloning as well as analysis of hybridisation and isolation of plasmid DNA. Nucleotide sequences, characterised by specific clones, were tested for potential needle structures. Also described are homology comparisons among FMD virus types A12, A10, O1, and C1.