Three-dimensional structure of the neuraminidase of influenza virus A/Tokyo/3/67 at 2.2 A resolution

An atomic model of the tetrameric surface glycoprotein neuraminidase of influenza virus A/Tokyo/3/67 has been built and refined based on X-ray diffraction data at 2.2 A resolution. The crystallographic residual is 0.21 for data between 6 and 2.2 A resolution and the r.m.s. deviations from ideal geometry are 0.02 A for bond lengths and 3.9 degrees for bond angles. The model includes amino acid residues 83 to 469, four oligosaccharide structures N-linked at asparagine residues 86, 146, 200 and 234, a single putative Ca2+ ion site, and 85 water molecules. One of the oligosaccharides participates in a novel crystal contact. The folding pattern is a beta-sheet propeller as described earlier and details of the intramolecular interactions between the six beta-sheets are presented. Strain-invariant residues are clustered around the propeller axis on the upper surface of the molecule where they line the wall of a cavity into which sialic has been observed to bind. Strain-variable residues implicated in binding to antibodies surround this site.     

Epidemiological studies on echovirus type 18 infection in Toyama Prefecture

Echovirus type 18 (echo 18) was isolated from six aseptic meningitis children in Fukumitsu-machi, Toyama Prefecture, from July to August, 1980. This was the first virologically-confirmed epidemic of aseptic meningitis due to echo 18 in Japan. Epidemiological studies on the prevalence of this virus among the inhabitants in Toyama Prefecture were also performed. The results are summarized as follows. (1) Significant increases in neutralizing antibody titers against echo 18 were observed in all the paired sera of aseptic meningitis patients from whom echo 18 was isolated. (2) In October, 1980, echo 18 was also isolated from healthy children or from infants suffering from gastroenteritis in other areas of Toyama Prefecture. (3) Among the sera collected from 50 children (aged smaller than or equal to 12) in Fukumitsumachi in December, 1980, neutralizing antibodies against echo 18 were detected only in the younger groups (aged smaller than or equal to 8), 58.9% of these age groups showing a titer of 4 or higher. (4) Another epidemic around 1963 by echo 18 in Toyama Prefecture was retrospectively suggested by the examinations of sera collected in 1978 and 1981 from inhabitants in various areas of Toyama Prefecture. (5) Neutralizing antibody titers against the strain isolated, No. 35'80, were significantly higher than those against strain 'Metcalf,' the prototype of echo 18, in most sera including both aseptic meningitis patients and healthy inhabitants.     

Structure of an escape mutant of glycoprotein N2 neuraminidase of influenza virus A/Tokyo/3/67 at 3 A

The three-dimensional structure of the membrane glycoprotein neuraminidase of an escape mutant of the influenza virus strain A/Tokyo/3/67 has been determined to 3 A (1 A = 0.1 nm) resolution by X-ray diffraction. The mutant virus, selected by growing the virus in the presence of a monoclonal antibody to the neuraminidase, is shown to have undergone a single amino acid change of lysine to glutamic acid at residue 368. The three-dimensional structure of the neuraminidase is identical with that reported for A/Tokyo/3/67, except for a purely local adjustment of the structure at position 368.     

2013—2018年广州市荔湾区流行性感冒流行特征及病原学分析

目的 掌握广州市荔湾区2013—2018年流行性感冒(influenza,简称流感)病例及病原学的流行特征,为制定流感防控策略提供科学依据。方法 运用描述性流行病学方法对荔湾区2013—2018年流感数据进行分析。结果 2013— 2018年广州市荔湾区共报告流感7 585例,其中2018年最高为2 691例,发病率283.26/10万;2013年最低,仅有528例,发病率57.78/10万。流感流行趋势每年出现1~2次流行高峰,高峰季节为春季和冬季;男女性别比1.23∶1,差异无统计学意义( P >0.05)。年龄以0~<5岁和5~<15岁组为主;职业以散居儿童、学生和幼托儿童为主,年龄和职业差异有统计学意义( P <0.05)。共检测流感样病例(influenza-like cases, ILI)咽拭子标本总数 6 110 份,其中,流感病毒阳性标本总数564份,阳性率9.23%;每年可有1~2次检出高峰,高峰季节为春季和冬季。流感病毒型别呈现新甲H1型、季H3型和B型交替流行趋势。结论 广州市荔湾区流感防控重点人群是15岁以下的散居、托幼儿童和中小学生,防控重点季节为春季和冬季。据此预测,2019年则需重点防控新甲H1型(A型)流感病毒。