Description of three new bat-associated species of hard ticks (Acari, Ixodidae) from Japan.

In Eurasia, the geographically most widespread ixodid tick species of the bat families Rhinolophidae Gray, Vespertilionidae Gray, and Miniopteridae Dobson were considered to belong to four species, Ixodesvespertilionis Koch, I.collaris Hornok, I.ariadnae Hornok, and I.simplex Neumann. Previous data attest that bat-associated tick species from Eastern Asia show remarkable genetic difference from the above four tick species, but in the absence of detailed morphological comparison these were regarded as conspecific. In this study we compensate for this lack of data on three bat-associated tick species, reporting their morphological comparison, as well as molecular and phylogenetic relationships. According to the results we describe the females of three tick species new to science, i.e., I.nipponrhinolophi Hornok & Takano, sp. nov., I.fuliginosus Hornok & Takano, sp. nov., and I.fujitai Hornok & Takano, sp. nov. In case of all three new tick species the cytochrome c oxidase subunit (coxI) gene showed remarkably high sequence differences from the species that they previously were thought to belong to, well exceeding the average limit delineating ixodid tick species. This, as well as observed morphological differences fully justify their taxonomical status as new species.

Epidemiological study of Kabuto Mountain virus, a novel uukuvirus, in Japan.

Kabuto Mountain virus (KAMV), the new member of the genus Uukuvirus, was isolated from the tick Haemaphysalis flava in 2018 in Japan. To date, there is no information on KAMV infection in human and animals. Therefore, serological surveillance of the infection among humans and wild mammals was conducted by virus-neutralization (VN) test and indirect immunofluorescence assay (IFA). Sera of 24 humans, 59 monkeys, 171 wild boars, 233 Sika deer, 7 bears, and 27 nutria in Yamaguchi Prefecture were analyzed by VN test. The positive ratio of humans, monkeys, wild boars, and Sika deer were 20.8%, 3.4%, 33.9% and 4.7%, respectively. No positive samples were detected in bears and nutria. The correlation coefficients between VN test and IFA in human, monkey, wild boar, and Sika deer sera were 0.5745, 0.7198, 0.9967 and 0.9525, respectively. In addition, KAMV was detected in one pool of Haemaphysalis formosensis ticks in Wakayama Prefecture. These results indicated that KAMV or KAMV-like virus is circulating among many wildlife and ticks, and that this virus incidentally infects humans.

Detection of a novel tick-borne flavivirus and its serological surveillance.

Tick-borne encephalitis virus (TBEV), a flavivirus that causes severe neurological symptoms in humans, has been found in Hokkaido, Japan. In the present study, we detected sequences from a novel tick-borne flavivirus, designated Yamaguchi virus (YGV), in liver and serum samples obtained from a wild boar in the Yamaguchi prefecture, Japan. Phylogenetic analysis revealed that YGV belongs to the TBEV complex and is closely related to Langat virus (LGTV). YGV was also detected by specific RT-PCR from 20 in 378 pools of ticks (2923 ticks) collected in Yamaguchi and Wakayama prefectures and from seven in 46 wild boar captured in Wakayama. The major ticks infected with YGV belong to the genus Haemaphysalis. Unfortunately, YGV could not be isolated from any samples from the RT-PCR positive wild boar or ticks. Therefore, ELISA for detection of antibodies against YGV was established using LGTV, and surveillance was performed among wild boar in 10 different prefectures on Honshu Island, the main island of Japan. The results showed that the seroprevalence of tick-borne flavivirus infection in the Wakayama and Hyogo prefectures of western Japan was significantly higher than that in the other prefectures, while antibodies against tick-borne flavivirus were not detected in any wild boar in the Tochigi prefecture in the eastern part of Japan. In addition, wild raccoons or masked palm civets in the Hyogo prefecture did not possess detectable antibodies against tick-borne flaviviruses. In conclusion, YGV appears to be maintained primarily among wild boar and ticks in the western part of Japan. YGV is the second flavivirus (after Japanese encephalitis virus) shown to be circulating on Honshu Island in Japan.

A role for CK2alpha/beta in Xenopus early embryonic development.

CK2 is expressed widely in early embryonic development in several animal models, however its developmental role is unclear. One of the substrates of CK2 that is important in embryonic development is beta-catenin, the transcriptional co-activator of the canonical Wnt signaling pathway. This pathway has been implicated in diverse aspects of embryonic development, including one of the earliest events in embryonic development, the establishment of the dorso-ventral embryonic axis. In Xenopus laevis, dorso-ventral axis formation is dependent upon stabilization of beta-catenin in the future dorsal side of the embryo. Since CK2 phosphorylation of beta-catenin stabilizes it, we hypothesized that CK2 might be critical to upregulation of beta-catenin in Xenopus embryos and to the process of axis establishment. Our results demonstrate that CK2 is required for dorsal axis formation and is for normal upregulation of Wnt signaling genes and targets. Thus, CK2 is a regulator of endogenous axis formation in vertebrates.

Protein kinase CK2 is required for dorsal axis formation in Xenopus embryos.

Dorsal axis formation in Xenopus embryos is dependent upon asymmetrical localization of beta-catenin, a transducer of the canonical Wnt signaling pathway. Recent biochemical experiments have implicated protein kinase CK2 as a regulator of members of the Wnt pathway including beta-catenin. Here, we have examined the role of CK2 in dorsal axis formation. CK2 was present in the developing embryo at an appropriate time and place to participate in dorsal axis formation. Overexpression of mRNA encoding CK2 in ventral blastomeres was sufficient to induce a complete ectopic axis, mimicking Wnt signaling. A kinase-inactive mutant of CK2alpha was able to block ectopic axis formation induced by XWnt8 and beta-catenin and was capable of suppressing endogenous axis formation when overexpressed dorsally. Taken together, these studies demonstrate that CK2 is a bona fide member of the Wnt pathway and has a critical role in the establishment of the dorsal embryonic axis.

CK2 phosphorylation of the armadillo repeat region of beta-catenin potentiates Wnt signaling.

Protein kinase CK2 is a ubiquitous serine/threonine kinase involved in many biological processes. It is overexpressed in many malignancies including rodent and human breast cancer, and is up-regulated in Wnt-transfected mammary epithelial cells, where it can be found in a complex with dishevelled and beta-catenin. beta-Catenin is a substrate for CK2 and inhibition of CK2 reduces levels of beta-catenin and dishevelled. Here we report that inhibition of CK2 using pharmacologic agents or expression of kinase inactive subunits reduces beta-catenin-dependent transcription and protein levels in a proteasome-dependent fashion. The major region of phosphorylation of beta-catenin by CK2 is the central armadillo repeat domain, where carrier proteins like axin and the adenomatous polyposis coli gene product APC interact with beta-catenin. The major CK2 phosphorylation site in this domain is Thr393, a solvent-accessible residue in a key hinge region of the molecule. Mutation of this single amino acid reduces beta-catenin phosphorylation, cotranscriptional activity, and stability. Thus, CK2 is a positive regulator of Wnt signaling through phosphorylation of beta-catenin at Thr393, leading to proteasome resistance and increased protein and co-transcriptional activity.