Genetic characterization of Anaplasma phagocytophilum strains from goats (Capra aegagrus hircus) and water buffalo (Bubalus arnee) by 16S rRNA gene, ankA gene and multilocus sequence typing

Anaplasma phagocytophilum is a Gram-negative obligate intracellular bacterium that replicates in neutrophil granulocytes. It is transmitted by ticks and causes tick-borne fever in domestic ruminants such as sheep, cattle and goats. However, in contrast to sheep and cattle little is known about the clinical course of infection in goats. We report here on three cases of symptomatic infection with A. phagocytophilum in two goats (Capra aegagrus hircus) and one water buffalo (Bubalus arnee). The animals showed symptoms and laboratory findings similar to sheep and cattle. To our knowledge, this is the first report on the symptomatic infection of water buffalos with A. phagocytophilum. The infecting strains were genetically characterized by 16S rRNA gene, ankA gene and multilocus sequence typing (MLST). Four other strains from asymptomatically infected goats were also included. The ankA sequences from five goats were part of the formerly described ankA gene clusters I and IV that are known to contain A. phagocytophilum strains from sheep and cattle. However, the sequences from one goat and from the water buffalo belonged to ankA gene cluster II that was formerly described to be restricted to roe deer. A similar observation was made for MLST as three goats clustered with sequences from sheep and cattle, whereas three other goats and the water buffalo were found to be part of the roe deer cluster. However, since most of the strains from sheep and cattle were distinct from the roe deer strains, roe deer might not represent major reservoir hosts for tick-borne fever in domestic ruminants. When differing parts of the 16S rRNA gene were used for typing the results were conflicting. This shows that the use of a standardized typing method such as MLST is highly desirable to generate easily comparable results.