Molecular epidemiology of enterovirus 71 infection in the Western Pacific Region

BACKGROUND: Recently, there have been large outbreaks of hand, foot and mouth disease (HFMD) mainly caused by enterovirus 71 (EV71) associated with severe neurological diseases in the Western Pacific Region (WPR). To monitor the realtime trend of EV71 transmission throughout the WPR, the authors conducted a molecular epidemiological analysis of EV71 infection. METHODS: Viruses were isolated from clinical samples from patients with HFMD or those with neurological complications. The EV71 isolates were identified by microneutralization assay. The VP4 and/or VP1 regions of recent EV71 isolates were sequenced and subjected to phylogenetic analysis using reference EV71 strains. RESULTS: The phylogenetic analysis of EV71 isolates from the WPR revealed two major genogroups, B and C, based on the nucleotide sequence alignment of the VP1 or VP4 region. These two major genogroups were further divided into subgenogroups, B1, B2, B3, and B4 and C1, C2, C3 and C4, respectively. CONCLUSIONS: The molecular epidemiological analyses of recent and previous EV71 isolates in the WPR indicated that two major genogroups of EV71 are co-circulating in Australia, Malaysia, Singapore, Taiwan and Japan. Recent EV71 isolates in Mainland China constitute a new distinct genetic cluster, subgenogroup C4. Two major lineages of EV71 are the major causative agents of the present HFMD epidemics in the WPR and both are considered to be neurovirulent.     

Clinical genetics,practice, and research of deafblindness: From uncollected experiences to the national registry in Japan

Deafblindness is a condition of combined vision and hearing loss that is extremely rare in children and young adults, as well as being a highly heterogeneous condition, with over 70 specific etiologies. Due to these features, sporadic clinical experiences have not been collated, which has hampered medical progress. Genetics plays a major role in the pathogenesis of deafblindness in children and young adults, with more than 50 hereditary syndromes and disorders associated with the condition, including CHARGE, Usher, Down, Stickler, and Dandy-Walker syndromes, which are the most common. Clinical diagnosis of deafblindness is often difficult, and a significant proportion of patients are undiagnosed. No curative therapy is currently available for the majority of patients with hereditary deafblindness; however, experimental studies using animal models have shown promising results by targeting specific genes that cause vision or hearing loss. In Japan, the Rare Disease Data Registry of Japan (RADDAR-J) has been established as a national registry of rare and intractable diseases. Diseases of deafblindness have been elected as a disease category in RADDAR-J. Currently, clinical and genomic data are being collected and analyzed using this system, with the aim of generating an overview of deafblindness to improve medical practice.     

Cytotoxic T‐lymphocyte‐associated protein 4 expressed by melanoma cells does not affect melanoma‐specific cytotoxic T lymphocytes in the effector phase

Cytotoxic T‐lymphocyte‐associated protein 4 (CTLA‐4) is one of the important molecules that regulate the anti‐melanoma T‐cell response. Currently, there are some reports showing that CTLA‐4 is expressed not only by T cells but also by various kinds of tumor cells, including melanoma cells. However, there is no report that shows the role of CTLA‐4 expressed by melanoma cells in melanoma‐specific cytotoxic T‐lymphocyte (CTL) response. In this report, we confirmed substantial CTLA‐4 expression and the localization of CTLA‐4 in melanoma cell lines and tissues. Also, we examined its impact on melanoma‐specific CTL in vitro, and found that CTLA‐4 expressed by melanoma cells does not affect melanoma‐specific CTL in the effector phase. Our findings suggest the importance of elucidating the role of CTLA‐4 expressed by melanoma cells, particularly in anti‐CTLA‐4 antibody therapy.     

Noisy signal amplification in ultrasensitive signal transduction

Because intracellular processes are inherently noisy, stochastic reactions process noisy signals in cellular signal transduction. One essential feature of biological signal transduction systems is the amplification of small changes in input signals. However, small random changes in the input signals could also be amplified, and the transduction reaction can also generate noise. Here, we show theoretically how the abrupt response of ultrasensitive signal-transduction reactions results in the generation of large inherent noise and the high amplification of input noise. The inherently generated noise propagates with amplification through intracellular molecular network. We discuss how the contribution of such transmitted noise can be shown experimentally. Our results imply that the switch-like behavior of signal transduction could be limited by noise; however, high amplification reaction could be advantageous to generate large noise, which would be essential to maintain behavioral variability.     

Ligand-independent activation of vascular endothelial growth factor receptor 2 by fluid shear stress regulates activation of endothelial nitric oxide synthase

Fluid shear stress generated by blood flowing over the endothelium is a major determinant of arterial tone, vascular remodeling, and atherogenesis. Nitric oxide (NO) produced by endothelial NO synthase (eNOS) plays an essential role in regulation of vascular function and structure by blood flow, but the molecular mechanisms that transduce mechanical force to eNOS activation are not well understood. In this study, we found that laminar flow (shear stress=12 dyne/cm2) rapidly activates vascular endothelial growth factor receptor 2 (VEGFR2) in a ligand-independent manner and leads to eNOS activation in cultured endothelial cells. Flow-stimulated VEGFR2 recruits phosphoinositide 3-kinase and mediates activation of Akt and eNOS. Inhibiting VEGFR2 kinase with selective inhibitors blocks flow-induced activation of Akt and eNOS and production of NO. Decreasing VEGFR2 expression with antisense VEGFR2 oligonucleotides significantly attenuates activation of Akt and eNOS. Furthermore, Src kinases are involved in flow-stimulated VEGFR2 because inhibiting Src kinases by PP2, a selective inhibitor for Src kinases, abolishes flow-induced VEGFR2 tyrosine phosphorylation and downstream signaling. Finally, we show that inhibiting VEGFR2 kinase significantly reduces flow-mediated NO-dependent arteriolar dilation in vivo. These data identify VEGFR2 as a key mechanotransducer that activates eNOS in response to blood flow.