ABSTRACTParasites of theBabesiadivergensAsia lineage, which are closely related toB. divergensin Europe andBabesiasp. strain MO1 in the United States, were recently reported in sika deer (Cervus nippon) in eastern Japan. To identify the tick vector(s) for this parasite, we conducted a field survey in Hokkaido, Japan, where the infection rate in sika deer is the highest in the country. A specific PCR system which detects and discriminates between lineages withinB. divergensand between those lineages andBabesia venatorumshowed thatIxodes persulcatus(11/822), but not sympatricIxodes ovatus(0/595) orHaemaphysalissp. (0/163) ticks, carriedB. divergensAsia lineage. Genomic DNA was archived from salivary glands of partially engorgedI. persulcatusfemales and three isolates ofB. divergensAsia lineage were newly described. The 18S rRNA gene sequence of the isolates formed the Asia lineage cluster with those previously described in sika deer isolates. One salivary gland also contained parasites ofBabesia microtiU.S. lineage, which were subsequently isolated in a hamsterin vivo.B. venatorum(strain Etb5) was also detected in oneI. persulcatustick. The 18S rRNA sequence of Etb5 was 99.7% identical to that ofB. venatorum(AY046575) and was phylogenetically positioned in a taxon composed ofB. venatorumisolates from Europe, China, and Russia. The geographical distribution ofI. persulcatusis consistent with that ofB. divergensin sika deer in Japan. These results suggest thatI. persulcatusis a principal vector forB. divergensin Japan and Eurasia, whereI. persulcatusis predominantly distributed.IMPORTANCETheBabesiadivergensAsia lineage of parasites closely related toB. divergensin Europe andBabesiasp. MO1 in the United States was recently reported inCervus nipponin eastern Japan. In this study, specific PCR for the Asia lineage identified 11 positives in 822 host-seekingIxodes persulcatusticks, a principal vector for many tick-borne disease agents. Gene sequences of three isolates obtained from DNA in salivary glands of female ticks were identical to each other and to those inC. nippon. We also demonstrate the coinfection ofB. divergensAsia lineage withBabesia microtiU.S. lineage in a tick salivary gland and, furthermore, isolated the latter in a hamster. These results suggest thatI. persulcatusis the principal vector forB. divergensas well as forB. microti, and both parasites may be occasionally cotransmitted byI. persulcatus. This report will be important for public health, since infection may occur through transfusion.
Photosynthetic induction responses to variable light under field conditions in three species grown in the gap and understory of a Fagus crenata forest