Structural analysis of a p44/msp2 expression site of Anaplasma phagocytophilum in naturally infected ticks in Japan

Abstract

Anaplasma phagocytophilum, an agent of human granulocytic anaplasmosis, infects neutrophils and causes an emerging tickborne febrile disease. The genome of this bacterium contains a large number of p44/msp2-related genes encoding 44 kDa major outer-membrane proteins, and it is known that a specific p44/msp2 gene is predominantly transcribed from a single expression locus. This study successfully characterized the genomic expression site for p44/msp2 (3.8 kb) in uncultured A. phagocytophilum from Ixodes persulcatus ticks inhabiting a northern part of Japan. Comparative analysis of the sequences revealed that the structures of the expression sites in Japanese A. phagocytophilum were similar to those of US strains from human patients and European strains from a dog and sheep, but omp-1N (upstream from p44/msp2) and a truncated recA (downstream from p44/msp2) in the p44/msp2 expression site seemed to share similarities with those of US and European strains. The central hypervariable region sequences of Japanese p44/msp2 were found to be quite diverse (24.4-100 % amino acid similarities) and distinct from their closest relatives from US human patients or animal host origins (56.3-97.6 % amino acid similarities) with some exceptions. Thus, this study provides significant information about the molecular characteristics of A. phagocytophilum in East Asia, as well as the global diversity of p44/msp2.

A Molecular and Serological Survey of <i>Rickettsiales</i> Bacteria in Wild Sika Deer (<i>Cervus nippon nippon</i>) in Shizuoka Prefecture, Japan: High Prevalence of <i>Anaplasma</i> Species

“…We designed some primers targeting to 16S rDNA to distinguish these 2 types of A. phagocytophilum (Table 1). In the primary experiment, the specificity of primer pairs used in this study was confirmed by PCR with several positive samples, such as DNA from Ixodes persulcatus ticks infected with A. phagocytophilum (human type) or from sika deer infected with A. phagocytophilum (deer type) that had been previously identified (14,17) (data not shown). Then, the PCR survey was conducted in spleen samples from 187 sika deer from Shizuoka, Japan.…”

Mechanisms of Obligatory Intracellular Infection with Anaplasma phagocytophilum

“…Although Ixodes ticks often feed on white-tailed deer, the deer are infected with the Ap-Variant 1 strain of A. phagocytophilum, rather than with the human strain, in the United States (146). Diverse A. phagocytophilum strains are also found in animals and ticks in Europe, Japan, and Russia (109,111,151,160,170,203,238,239), where HGA has been rarely reported. These findings imply that the zoonosis potential of A. phagocytophilum depends not only on the transmissibility, habitats, and population density of ticks and infected mammals (90) but also on the genetic variations of A. phagocytophilum.…”

“…A. phagocytophilum strains show a minor degree of variation in the nucleotide sequence in 16S rRNA and groESL. The p44, p44ESup1 (omp-1N), msp2 (different from p44), and ankA genes contain major strain variation (23,44,61,67,111,134,135,150,153,203,224,239). These and potentially other genes may allow more detailed comparisons among strains.…”

Dual Presence of <i>Anaplasma phagocytophilum</i> and Its Closely Related <i>Anaplasma</i> sp. in Ixodid Ticks in Hokkaido, Japan, and Their Specific Molecular Detection

“…Molecular detection and characterization (based on P44/MSP2 gene) of A. phagocytophilum strains from ixodid ticks in Japan revealed closer identities with the strains found in other countries [25,37]. However, lower sequence identities were observed on 16S rRNA characterization [38].…”