Two weeks after the Great Tohoku earthquake followed by the devastating tsunami, we have sent open-ended questionnaires to a randomly selected sample of Twitter users and also analysed the tweets sent from the disaster-hit areas. We found that people in directly affected areas tend to tweet about their unsafe and uncertain situation while people in remote areas post messages to let their followers know that they are safe. Our analysis of the open-ended answers has revealed that unreliable retweets (RTs) on Twitter was the biggest problem the users have faced during the disaster. Some of the solutions offered by the respondents included introducing official hash tags, limiting the number of RTs for each hash tag and adding features that allow users to trace information by maintaining anonymity.

The hemagglutinin (HA) of influenza A virus is a homotrimeric glycoprotein with an ectodomain composed of a globular head and stem region (26). Both regions carry N-linked oligosaccharide chains. The appearance or disappearance of oligosaccharides on the globular head has been reported to occur naturally during antigenic drift of influenza A/H3N2 viruses from 1968 to 1975 (15, 24, 25). The acquisition of new oligosaccharides is an important mechanism underlying the antigenic drift of HA. Antigenic drift occurs by accumulation of a series of point mutations resulting in amino acid substitutions in antigenic sites on the surface of the HA (1, 25). These substitutions prevent neutralization by antibodies directed against previous epidemic strains.Based on analysis of the HA sequences of A/H3N2 viruses isolated from 1968 to 2002, the oligosaccharide chains on the globular head show large variations in number among different A/H3N2 isolates, although five glycosylation sites at Asn residues 8, 22, 38, 285, and 483 on the stem region are strictly conserved. Most of the A/H3N2 viruses that circulated between 1968 and 1974 (represented by A/Aichi/2/68) had only two oligosaccharides at residues 81 and 165 on the globular head of the HA (Fig. 1A). However, viruses isolated in 1975 (represented by A/Victoria/3/75) had lost a glycosylation site at residue 81 and gained two new sites at residues 63 and 126. The 1986 isolates (represented by A/Memphis/6/86) had acquired a new carbohydrate attachment site at residue 246, and the 1997 isolates (represented by A/Sydney/5/97) had obtained two additional sites at residues 122 and 133. Some recent isolates (represented by A/Panama/2007/99) had often obtained a novel site at residue 144. Thus, the A/H3N2 viruses recently circulating have six or seven glycosylation sites on the globular head of the HA, although whether these are glycosylated is not known. Moreover, the HAs of influenza A/H1N1 viruses and influenza B viruses isolated recently also possess several oligosaccharide chains on their globular head. These observations suggest that the addition of new oligosaccharides to the globular head of the HA may provide influenza viruses with an increased ability to prevail among humans (14). Interestingly, however, examination of the available HA sequences of influenza A/H2N2 viruses showed that none of the HAs had obtained a new glycosylation site on the globular head, and they had only one carbohydrate chain at position 169 (21).We previously studied the antigenic structure of the HA of A/H2N2 virus and revealed that most of the escape mutants selected by monoclonal antibodies had acquired a new glycosylation site at position 131, 160, or 187 on the tip of the HA (21,22,23). The results indicated that A/H2N2 viruses have the potential to gain at least one additional oligosaccharide on the globular head of the HA, although this has never occurred during 11 years of its circulation in humans. We constructed HA glycosylation site mutants containing one to three oligosaccharides at posi...

In a 9-year survey from December 1990 to December 1999 in Sendai City, Japan, we succeeded in isolating a total of 45 strains of influenza C virus. These 45 strains were isolated in clusters within 4 months in a year, especially from winter to early summer. Previous studies of the hemagglutinin-esterase genes of various influenza C virus isolates revealed the existence of five distinct virus lineages (Aichi/1/81-, Yamagata/26/81-, Mississippi/80-, Sao Paulo/82-, and Kanagawa/1/76-related lineage) in Japan between 1970 and the early 1990s

The antigenic structure of influenza A/H2N2 virus haemagglutinin (HA) was analysed using 19 monoclonal antibodies (MAbs) against the HA of A/Kayano/57. The antibodies were classified into three groups : group I had both haemagglutination inhibition and neutralization activities, group II had neutralization activity but no haemagglutination inhibition activity and group III had neither activity.

Long-term virus shedding after the disappearance of clinical symptoms was observed. Caution should be exercised when handling the excrement of infants and young children infected with NV.