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The receptivity of the Blasius boundary layer over a semi-infinite flat plate with an elliptic leading edge and of aspect ratio five was investigated using a direct numerical solution of two-dimensional Navier-Stokes equations. The result of the computation where the slip condition is applied to the fluctuating component of velocity at the wall surface is compared with that of an ordinary computation using a nonslip condition. Another numerical experiment is performed where no vorticity fluctuation is supplied from a freestream while prerecorded values of vorticities at the wall in response to the passage of convecting fluctuations are used as the wall vorticity boundary condition. It is shown that vorticity fluctuations in the boundary layer can be classified according to their wavelengths. Waves with longer wavelengths originate from the freestream, whereas waves with shorter wavelengths close to T-S waves originate from the surface of the plate. In another numerical experiment, the slip boundary condition against the fluctuation component of vorticity is applied to the limited area of the wall surface. The aim of the study is to determine the part of the elliptic leading edge or flat plate that induces vorticity fluctuations, thereby resulting in the creation of T-S waves. The numerical results show that the contribution of vorticity fluctuations originating from the juncture is the most crucial, whereas the vorticities supplied in the elliptic leading-edge surface negatively affect the amplitude of vorticity fluctuations inside the boundary layer. And, the stagnation section did not show positive contribution. [ABSTRACT FROM AUTHOR]

Getah virus (GETV), belonging to the genus Alphavirus within the family Togaviridae, is a mosquito-borne virus that causes fever, rash, and edema in horses and fatalities and pregnancy disorders in pigs. It has caused occasional outbreaks in horse populations in Japan, China, and India, and endemic areas are gradually expanding, particularly in Asia and Oceania. In this study, we isolated a new GETV strain from Culex tritaeniorhynchus mosquitoes collected from Nagasaki Prefecture, Japan in 2022. Phylogenetic analysis revealed that this new strain, 22IH8, is more closely related to previous Chinese strains than to the strains prevalent in Japan in the 2010s. Furthermore, some amino acid substitutions in the viral proteins of strain 22IH8 were found to be common with those in previous Chinese strains. These results suggest that 22IH8 strain may have recently invaded the Japanese archipelago from mainland Asia. The antiserum against the current vaccine strain, MI-110, showed high neutralization activity against the 22IH8 strain indicating the efficiency of the current vaccine for horses in Japan.

Cervus nippon (sika deer) are widely distributed throughout eastern Asia. Deer possess a variety of antibodies against several zoonotic pathogens, indicating that they act as reservoir of zoonoses. In this study, we reported the characterization of cultured cells derived from sika deer and evaluated their susceptibility to arthropod-borne viruses to clarify their usefulness in virological studies. Cells derived from testicular tissue in Dulbecco's modified eagle medium with 16% fetal bovine serum started growing as primary cultured cells. The diploid cells consisted of 68 chromosomes, consistent with those of Japanese sika deer previously reported. The phylogenetic analysis showed the cells formed a robust clade with Japanese population of C. nippon, indicating that the cultured cells established in this study were originated from the Japanese sika deer. The cells immortalized by the simian virus 40 T-antigen were predominantly spindle-shaped cells exhibiting adhesive properties, and cultivated at 37°C and 5% CO 2 , which are common culture conditions for many mammalian cell lines. Western blotting analysis indicated that the cultured cells were multiple types of cells that coexist, including at least epithelial, fibroblast, and also Leydig cells. We confirmed that the cells have susceptibility to several arboviruses distributed in Japan: Getah virus, Japanese encephalitis virus, Oz virus, and severe fever with thrombocytopenia syndrome virus, but not to Tarumiz tick virus. From these results, the cells contribute to clarify the role of sika deer as a reservoir of zoonoses in nature and deer-associated experimental research at the cellular and molecular levels., (© 2024. The Society for In Vitro Biology.)

Coltiviruses, belonging to the genus Coltivirus within the family Spinareoviridae, are predominantly tick-borne viruses. Some of these species have been implicated in human diseases; however, their diversity, geographical distribution, and evolutionary dynamics remain inadequately. Therefore, this study was undertaken to explore the phylogenetic evolution of coltiviruses and related viruses. Our results revealed the detection of novel coltivirus-related sequences in adult female Haemaphysalis megaspinosa ticks collected from Kanagawa Prefecture, Japan. Molecular phylogenetic analysis revealed a close association between the sequences and the genome sequences of known coltivirus-related viruses, namely Qinghe tick reovirus and Fennes virus. The putative coltivirus-related virus was tentatively designated the Nakatsu tick virus. This study provides insights into the phylogenetic evolution of coltiviruses and related viruses.

In 2010, Jingmen tick virus (JMTV) was discovered in ticks in China and has been shown to be distributed in several regions worldwide. Recently, cases of JMTV infection in humans have been reported in China and Kosovo, and have attracted much attention as an emerging tick-borne disease. In this study, we detected the JMTV genome in Amblyomma testudinarium ticks collected in Kanagawa Prefecture, Japan, during tick-borne virus surveillance conducted in the Kanto Region. Phylogenetic analysis revealed that the new JMTV strain was closely related to previous strains detected in Japan. This suggests that JMTV may have been maintained during an independent natural transmission cycle in Japan. In addition, unlike other countries and regions, all JMTV strains in Japan were detected only in A. testudinarium ticks, suggesting that this tick species is the primary JMTV vector in Japan. This is the first report of JMTV in the Kanto Region. Further studies are required to elucidate the potential risk of infection with this tick-borne virus in Japan. In particular, the prevalence of JMTV in wild animals should be examined to clarify its geographical distribution, host range, and transmission cycle.

Arthropod-derived cell lines serve as crucial tools for studying arthropod-borne viruses (arboviruses). However, it has recently come to light that certain cell lines harbor persistent infections of arthropod-specific viruses, which do not cause any apparent cytopathic effects. Moreover, some of these persistent viral infections either inhibit or promote the growth of arboviruses. Therefore, it is of utmost importance to identify the presence of such persistent viruses and understand their impact on arboviral infections. In this study, we conducted a comprehensive virome analysis of several arthropod-derived cell lines, including mosquito-derived NIID-CTR, Ar-3, MSQ43, NIAS-AeAl-2, CCL-126 cells, and tick-derived IDE8 cells, along with flesh fly-derived NIH-Sape-4 cells. The aim was to determine if these cells were infected with persistent viruses. The results revealed the presence of 15 persistent viruses in NIID-CTR, Ar-3, MSQ43, NIAS-AeAl-2, and IDE8 cells. Among these, 11 were already known arthropod-specific viruses, while the remaining 4 were novel viruses belonging to Orthophasmavirus, Rhabdoviridae, Totiviridae, and Bunyavirales. In contrast, CCL-126 and NIH-Sape-4 cells appeared to be free of viral infections. This study provides valuable insights into the diversity and latency of arthropod-specific viruses within arthropod-derived cell lines. Further investigations are required to explore persistent viral infections in other arthropod-derived cell cultures and their effects on arbovirus replication. Understanding these factors will enhance the accuracy and reliability of experimental data obtained using these cell lines., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)