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Influenza C virus is a pathogen that causes acute respiratory illness in children and results in the hospitalization of infants. The antigenicity of the hemagglutinin esterase (HE) glycoprotein is highly stable, and it is not yet known whether antigenic changes contribute to the worldwide transmission and the occurrence of outbreaks of influenza C virus. Here, we performed antigenic analysis of 84 influenza C viruses isolated in Yamagata, Japan, during a 4-year period from 2015 to 2018 and analyzed sequence data for strains of the virus from Japan and many other parts of the world. Antigenic and phylogenetic analyses revealed that 83 strains belonged to the C/Sao Paulo lineage, and two sublineage strains, the Aichi99 sublineage and Victoria2012 sublineage, cocirculated between 2016 and 2018. Aichi99 sublineage strains exhibiting decreased reactivity with the monoclonal antibody YA3 became predominant after 2016, and these strains possessed the K190N mutation. Residue 190 is located in the 190-loop on the top side of the HE protein within a region that is known to show variation that does not impair the biological activity of the protein. The Aichi99 sublineage strains possessing the K190N mutation were detected after 2012 in Europe, Australia, the USA, and Asia as well as Japan. These observations suggest that antigenic variants with K190N mutations have circulated extensively around the world and caused outbreaks in Japan between 2016 and 2018. Our study indicated that the 190-loop is an important antigenic region, and the results suggested that changes in the 190-loop have contributed to the extensive transmission of the virus.

The antigenicity of the hemagglutinin esterase (HE) glycoprotein of influenza C virus is known to be stable, however, information about residues related to antigenic changes has not yet been fully acquired. Using selection with anti-HE monoclonal antibodies, we previously obtained some escape mutants and identified four antigenic sites, namely, A-1, A-2, A-3, and Y-1. To confirm whether the residues identified as the neutralizing epitope possibly relate to the antigenic drift, we analyzed the growth kinetics of these mutants. The results showed that some viruses with mutations in antigenic site A-1 were able to replicate to titers comparable to that of the wild-type, while others showed reduced titers. The mutants possessing substitutions in the A-2 or A-3 site replicated as efficiently as the wild-type virus. Although the mutant containing a deletion at positions 192 to 195 in the Y-1 site showed lower titers than the wild-type virus, it was confirmed that this region in the 190-loop on the top side of the HE protein is not essential for viral propagation. Then, we revealed that antigenic changes due to substitutions in the A-1, A-3, and/or Y-1 site had occurred in nature in Japan for the past 30 years. These results suggest that some residues (i.e., 125, 176, 192) in the A-1 site, residue 198 in the A-3 site, and residue 190 in the Y-1 site are likely to mediate antigenic drift while maintaining replicative ability.

The purpose of this study is to develop a soft-material power-assist glove for hand grasping in daily life by older or disabled persons. Such a glove must be compact, lightweight, and flexible. The glove we developed consists of rubber and cloth, and is user-friendly. This paper describes the types of rubber muscle and the soft power-assist glove, together with control based on human intent and the effectiveness of our proposal.

The effect of EDTA was observed on the hydrolysis of IMP by an alkaline phosphatase of carp muscle. Results obtained may be summarized as follows: 1. EDTA depressed not only instantaneously the initial reaction velocity, but also time-dependantly the reaction velocity of IMP hydrolysis by the phosphatase. (Fig. 1) 2. The instantaneous effect of EDTA was apparently removed by the addition of excess Mg++. (Table 1 and Fig. 2) 3. During the preincubation of the phosphatase with EDTA, the activity, which was deter-mined after the removal of the EDTA effect by the addition of excess Mg++, was gradually de-creased. (Fig. 3) That is, the phosphatase was gradually inactivated irreversibly by EDTA. 4. The phosphatase was denatured by heat at a lower temperature in the presence of EDTA than in the absence. (Fig. 4) 5. From these results, EDTA was supposed to inhibit the phosphatase reaction by such mechanisms, that EDTA may combine instantaneously and reversibly with a metal ion which is essential to the phosphatase reaction, and the metal free phosphatase thus occurred may gradu-ally and temperature-dependantly be denatured.

コイ筋肉中のIMP分解に関与する酵素について筋肉細胞内分布を調べ, その酵素を精製し, さらに2, 3の性質を調べた結果は, 次のとおりである。1) 本酵素活性の大半は, 筋肉細胞内のミクロソームと考えられる特定顆粒中に分布する。2) 本酵素を超遠心分離, ブタノール処理, DEAEカラムクロマトグラフによって精製した。その結果416倍 (区分I) 264倍 (区分II) に精製された2種の酵素がえられた。3) 精製酵素すなわち区分IおよびIIは, いずれもpH7.5付近に至適pHを有する5′-Nucleotidaseである。4) IMPを基質とした場合のpKmは, 区分Iでは4.31区分IIでは4.57であり, 区分IにのみMg++存在下でpH-活性曲線のpH 9付近に変曲点がみられた。これらの点をのぞくと両酵素の性質はかなりよく類似しているものと考えられる。