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Junya Yamagishi

Publications and source records attributed to Junya Yamagishi.

4 recordsLinked to original sources
PubMed2025

ves1α genes expression is the major determinant of Babesia bovis-infected erythrocytes cytoadhesion to endothelial cells.

Babesia bovis causes the most pathogenic form of babesiosis in cattle, resulting in high mortality in naive adults. This parasite invades red blood cells (RBCs) within the bovine hosts where they multiply and produce clinical disease. Babesia bovis exports numerous proteins into invaded RBCs changing its properties. Thus, the infected RBCs (iRBCs) are capable to cytoadhere in the microvasculature of internal organs and brain, leading to respiratory distress, neurologic signs, and mortality. Variant Erythrocyte Surface Antigen 1 (VESA1) is one of those exported proteins by B. bovis which represents a major virulence factor due to its central role in immune evasion by antigenic variation and intravascular parasite sequestration. VESA1 is a heterodimer protein encoded by ves1α and ves1β multigene family and localized on the ridges, the focal point for cytoadhesion. To gain further insights into the molecular mechanisms of cytoadhesion of B. bovis, we panned the parasites with bovine brain microvasculature endothelial cells, which resulted in obtaining several clones with different cytoadherence abilities. The transcriptome analysis of 2 high and 2 low cytoadherent clones revealed that ves1α sequences were diversified, likely resulting from genomic recombination. On the other hand, ves1β sequences were almost identical among these 4 clones. Insertion and expression of ves1α of a clone with high binding into ef-1α locus of a low binding clone increased cytoadherence confirming the role of ves1α suggested by our transcriptome data. Whole genome sequencing of cytoadherent clones revealed active locus of ves1 on chromosome 2. These results suggest that VESA1a proteins encoded by ves1α genes determine the cytoadherence strength of B. bovis and they are in the active site for recombination.

Animals↗
PubMed2006

Expression of Autographa californica multiple nucleopolyhedrovirus genes in mammalian cells and upregulation of the host beta-actin gene.

The gene expression of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) was examined in two types of mammalian cells, human HeLa14 and hamster BHK cells. DNA microarray analysis followed by reverse transcription-PCR identified at least 12 viral genes transcribed in both HeLa14 cells and BHK cells inoculated with AcMNPV. 5' rapid amplification of cDNA ends was carried out to examine the transcriptional fidelity of these genes in HeLa14 cells. The transcription of ie-1, ie-0 and gp64 was initiated at a baculovirus early gene motif, CAGT, accompanied by a TATA motif. In addition, the same splicing observed for ie-0 mRNA in Sf9 cells occurred in HeLa14 cells. While the transcription initiation sites for pe38 and p6.9 were not located in the CAGT motif, most of them were in a typical eukaryotic RNA polymerase II promoter structure (a conventional TATA motif and/or an initiator). Interestingly, the expression of beta-actin was upregulated in the mammalian cells inoculated with AcMNPV. Subsequent experiments using UV-inactivated virus confirmed the upregulation, suggesting that de novo synthesis of viral products is not required for the event. These results indicated that the AcMNPV genome acts as a template for transcription in mammalian cells through the usual infection pathway, though there is no evidence for the functional expression of viral genes at present.

Actins↗
PubMed2005

The use of a recombinant baculovirus expressing a chitinase from the hard tick Haemaphysalis longicornis and its potential application as a bioacaricide for tick control.

Baculoviruses are specific insect pathogens used as selective biological insecticides on lepidopteran insects. We have tested a recombinant baculovirus expressing a chitinase gene for its efficacy as a tick bioacaricide. The recombinant Autographa californica multiple nuclear polyhedrosis virus expressing a chitinase enzyme (AcMNPV-CHT1) from the hard tick, Haemaphysalis longicornis, was constructed and found to have a novel bioacaricidal effect against ticks. The recombinant baculovirus was used to express the chitinase enzyme in Spodoptera frugiperda (Sf9) insect cells. Topical application of the supernatant harvested from the insect cell culture was found to cause mortality in nymphal ticks of H. longicornis. High temperature (>30 degrees C) and infrared radiation affected the chitinase enzyme activity and recombinant baculovirus infectivity by reducing the speed of tick killing by 60%. A mixture of recombinant virus and chitinase was found to kill ticks faster (p < 0.01) than pure chitinase and recombinant virus alone. Thus, the recombinant virus showed a synergistic effect with the foreign chitinase gene. In order to reduce the excessive use and cost of acaricides, it was found that a mixture of recombinant virus and flumethrin could halve the dose of the chemical acaricide used. These findings are important for the safe use of the recombinant virus expressing chitinase as a bioacaricide against ticks.

Animals↗