Timiryazevskaya, Moscow, 127550 Russia A b s t r a c t acute disease in cattle herds which is associated with anemia, fever, rapid loss of milk production and weight, abortion, and, in some cases, death of the infected cattle. is a rickettsial pathogen responsible for bovine anaplosmosis, the is transmitted by ticks and biting insects. <...> Diagnosis of bovine anaplasmosis is made by microscopic examination of blood smears stained with Giemsa stain, but this method is not useful to detect presymptomatic animals. <...> Several serological tests have used extensively for epidemiological studies, but they do not discriminate between different as a target DNA for PCR. <...> Msp4 is a dominant immune protein of outer membrane of all knowen to date. <...> The primers for phylogenetic analysis in in the blood of cattle. <...> The analysis of sequence of different isolates and closely related species, including species. <...> A real-time polymerase chain reaction (PCR) combines high specificity with accurate measurement of DNA copy number and allows quantification of the targeted pathogen DNA. <...> The goal of this study was to develop a real-time PCR assay for differential detection of , revealed species-specific areas, which were used for design of primers and TaqMan probe (MSP4-F 5′-CATGAGTCACGAAGTGGCT-3′ and MSP4-R 5′-GGCACACT-CACATCAATC-3′, MSP4-probe 5′-(Cy5)-AAGGGGGAGTAATGGGAGGTAGCT-3′) for amplification and detection of 177 bp fragment of homology to gene by a real time PCR. <...> In the amplified nucleotide sequences a 99 to 100 % fragments was found in different isolates of sensitivity of our PCR test, we used pGEM fragment of assay was able to detect as few as 102 of and gene, diluted to obtain samples with 100-107 gene in the analyzed DNA sample. <...> Analytical specificity of the developed primers and the MSP4-probe was proved in tests with DNA of sheep naturally infected by , , and also DNA isolated from cows with infection pre-detected by sequencing. <...> In these samples no increased fluorescence characteristic of probes from animals infected by was observed with no PCR products identified. <...> Thus, the method specificity allowed and to differentiate The developed method of on the basis on amplification and detection of the tion of anaplasmosis and epidemiological studies. <...> Keywords: , , family identification gene fragment using a real time PCR differed from known analogues with high sensitivity, rapidity and opportunity of quantitative <...>