Influenza: A Clinical Update Following a Century of Influenza Science

Although influenza science has come a long way since the 1918 Spanish flu pandemic, influenza continues to be a leading cause of morbidity and mortality. This review provides current, evidence-based recommendations regarding influenza prevention, diagnosis, and treatment. Nurse practitioners can help reduce influenza-associated morbidity and mortality by receiving annual influenza vaccinations, encouraging patients and community members to receive annual influenza vaccinations, developing and implementing strategies to improve influenza vaccination rates, encouraging preventive personal and community nonpharmaceutical interventions during influenza outbreaks, and by routinely reviewing and implementing current influenza recommendations from the Centers for Disease Control and Prevention.     

Oligonucleotide microchip for subtyping of influenza A virus

Background Influenza A viruses are classified into subtypes depending on the antigenic properties of their two outer glycoproteins, hemagglutinin (HA) and neuraminidase (NA). Sixteen subtypes of HA and nine of NA are known. Lately, the circulation of some subtypes (H7N7, H5N1) has been closely watched because of the epidemiological threat they present. Objectives This study assesses the potential of using gel‐based microchip technology for fast and sensitive molecular subtyping of the influenza A virus. Methods The method employs a microchip of 3D gel‐based elements containing immobilized probes. Segments of the HA and NA genes are amplified using multiplex RT‐PCR and then hybridized with the microchip. Results The developed microchip was validated using a panel of 21 known reference strains of influenza virus. Selected strains represented different HA and NA subtypes derived from avian, swine and human hosts. The whole procedure takes 10 hours and enables one to identify 15 subtypes of HA and two subtypes of NA. Forty‐one clinical samples isolated during the poultry fall in Novosibirsk (Russia, 2005) were successfully identified using the proposed technique. The sensitivity and specificity of the method were 76% and 100%, respectively, compared with the ‘gold standard’ techniques (virus isolation with following characterization by immunoassay). Conclusions We conclude that the method of subtyping using gel‐based microchips is a promising approach for fast detection and identification of influenza A, which may greatly improve its monitoring.     

Multiple clusters of A(H1N1)pdm09 virus circulating in severe cases of influenza during the 2010–2011 season: A phylogenetic and molecular analysis of the neuraminidase gene

The molecular characterization of circulating influenza A viruses is crucial to detect mutations potentially involved in increased virulence, drug resistance and immune escape. A molecular and phylogenetic analysis of A(H1N1)pdm09 neuraminidase (NA) gene sequences from different patient categories defined according to the severity of influenza infection were analyzed. A total of 126 influenza A(H1N1)pdm09 positive samples from patients with severe infections in comparison with those with moderate and mild infections was performed in Lombardy (Northern Italy, nearly 10 million inhabitants) during the 2010–2011 season. NA sequences included in this study segregated into five distinct clusters. Nineteen amino acid substitutions were detected exclusively in NA sequences of viruses identified in patients with severe or moderate influenza infection. Three of them (F74S, S79P, E287K) were observed in virus strains with the 222G/N hemagglutinin mutation. None of NA sequences under study had mutations related to the resistance to the NA inhibitors. Four out of 126 (3.2%) NA sequences from patients with severe infection lost a N‐linked glycosylation site due to the change from N to K at residue 386. Two additional N‐linked glycosylation sites in the NA stalk region (residues 42 and 44) were found in 12 (9.5%) NA sequences. Sporadic NA mutations were detected in NA viral sequences from critically ill patients, and no variants with reduced sensitivity to NA inhibitors were observed either in treated or untreated patients. J. Med. Virol. 85: 944–952, 2013. © 2013 Wiley Periodicals, Inc.     

Characterization of oseltamivir‐resistant influenza A(H1N1)pdm09 viruses in Taiwan in 2009–2011

The early isolated swine‐origin influenza A(H1N1)pdm09 viruses were susceptible to oseltamivir; however, there is a concern about whether oseltamivir‐resistant influenza A(H1N1)pdm09 viruses will spread worldwide as did the oseltamivir‐resistant seasonal influenza A(H1N1) viruses in 2007–2008. In this study, the frequency of oseltamivir resistance in influenza A(H1N1)pdm09 viruses was determined in Taiwan. From May 2009 to April 2011, 1,335 A(H1N1)pdm09‐positive cases in Taiwan were tested for the H275Y mutation in the neuraminidase (NA) gene that confers resistance to oseltamivir. Among these, 15 patients (1.1%) were found to be infected with H275Y virus. All the resistant viruses were detected after the patients have received the oseltamivir. The overall monthly ratio of H275Y‐harboring viruses ranged between 0% and 2.88%, and the peak was correlated with influenza epidemics. The genetic analysis revealed that the oseltamivir‐resistant A(H1N1)pdm09 viruses can emerged from different variants with a great diversity under drug pressure. The ratio of NA/HA activities in different clades of oseltamivir‐resistant viruses was reduced compared to those in the wild‐type viruses, indicating that the balance of NA/HA in the current oseltamivir‐resistant influenza A(H1N1)pdm09 viruses was interfered. It is possible that H275Y‐bearing A(H1N1)pdm09 virus has not yet spread globally because it lacks the essential permissive mutations that can compensate for the negative impact on fitness by the H275Y amino acid substitution in NA. Continuous monitoring the evolution patterns of sensitive and resistant viruses is required to respond to possible emergence of resistant viruses with permissive genetic background which enable the wide spread of resistance. J. Med. Virol. 85:379–387, 2013. © 2012 Wiley Periodicals, Inc.     

昆明市2009～2013年 B 型流感病毒血凝素及耐药基因分析

目的：研究B型流感病毒HA、NA全基因序列,为流感防控提供支持。方法从云南省疾病预防控制中心流感实验室分离毒株中挑选代表株进行H A和N A全基因序列分析。结果发现Bv型毒株和标准株比有K129N、K80R、K48E的变异,其中K129N在120环区域,除2009年分离株外,其他Bv株均有75位点的变异。By毒株HA基因相同突变位点比较多,如N116K、S150I、N165Y、S229D、D196N等,云南分离株都有D196N的变异位点,增加了糖基化位点的可能性。研究发现所有的NA基因没有发生耐药性基因的突变,同源性相对比较高,但有基因重组毒株生成。结论云南分离株B型流感病毒突变位点多,并且有重组毒株生成,说明加强监测耐药株的重要性。     

山东省2017—2018年B型流感病毒药物敏感性检测及神经氨酸酶基因特征分析

目的 检测山东省2017-2018流感监测年度B型流感病毒对神经氨酸酶抑制剂的药物敏感性,分析其神经氨酸酶(NA)基因特征。方法 选取山东省2017—2018年分离的18株B型流感病毒(Yamagata系16株,Victoria系2株),通过生物学耐药实验检测病毒对奥司他韦和扎那米韦的药物敏感性。提取病毒核酸后一步法RT-PCR扩增NA基因片段,双向测定核苷酸序列,对基因序列和氨基酸序列特征比对分析。结果 在检测的18株B型流感病毒中,有1株Yamagata系病毒对奥司他韦和扎那米韦2种药物的敏感性均降低,此株病毒的NA基因发生H274Y位点突变。其余15株Yamagata系病毒和2株Victoria系病毒均为奥司他韦及扎那米韦的敏感株。结论 随机选取的18株B型流感病毒中大多数病毒对神经氨酸酶抑制剂敏感,临床上可继续使用此类药物对流感患者进行治疗。应加强耐药性监测,警惕耐药株的出现。     

Productivity, apoptosis, and infection dynamics of influenza A/PR/8 strains and A/PR/8-based reassortants

In cell culture-based influenza vaccine production significant efforts are directed towards virus seed optimization for maximum yields. Typically, high growth reassortants (HGR) containing backbones of six gene segments of e.g. influenza A/PR/8, are generated from wild type strains. Often, however, HA and TCID₅₀ titres obtained do not meet expectations and further optimization measures are required.     

江苏省2013年甲型H1N1(09pdm)流感病毒血凝素和神经氨酸酶分子特征分析

目的:分析江苏省2013年甲型H1N1(09pdm)流感病毒血凝素(hemagglutinin,HA)和神经氨酸酶(neuraminidase,NA)变异情况,分析其遗传进化特征?方法:按照流感样病例定义,收集江苏省各哨点医院流感样病例标本,阳性样本经病毒分离培养及亚型鉴定?选取2013年不同时间段?不同地区具有代表性的14株甲型H1N1(09pdm)阳性毒株,利用特异性引物扩增HA?NA基因,测序并分析其遗传进化特征?结果:14株分离毒株与疫苗株A/California/07/2009(H1N1)的HA基因核苷酸和氨基酸同源性分别为97.6%~98.4%和96.5%~98.0%?NA基因核苷酸和氨基酸同源性分别为98.4%~98.9%和97.0%~98.5%?遗传进化分析表明,14株分离株HA和NA基因分属于不同的进化谱系?分子特征表现为HA氨基酸序列出现D114N?K300E?E516K的变异,NA分子特征表现为N44S位点变异?从2013年左右开始甲型H1N1(09pdm)流感基因多样性增加;通过FEL模型得到一个正向压力选择HA氨基酸位点310,一个正向压力选择NA氨基酸位点4,通过REL模型得到9个正向压力选择HA氨基酸位点179?180?239?301?303?310?311?312?313(含位点310),5个正向压力选择NA氨基酸位点4?23?52?287?374(含位点4)?HA蛋白具有9个潜在糖基化位点,7个位于HA1上,2个位于HA2上;NA蛋白共有9个潜在糖基化位点?14株分离毒株在NA蛋白酶活性中心及周围辅助位点上均未发现变异?结论:2013年江苏省甲型H1N1(09pdm)流感HA?NA基因变异加快,遗传多样性增加,未来的遗传进化值得进一步关注?     

Peramivir: an intravenous neuraminidase inhibitor

Introduction: Peramivir (BCX-1812, RWJ-270201) is a highly selective inhibitor of influenza A and B neuraminidase that has recently been approved in the USA by the FDA to treat acute, uncomplicated influenza in adults.

Areas covered: This review examines the discovery and development of peramavir as well as its role in the treatment of influenza. Peramivir is currently the only FDA-approved anti-influenza agent that can be given as an intravenous injection, granting it a unique role in therapy with the potential to improve adherence and outcomes in patients who are unable to tolerate oral agents. In vitro, animal, human and safety data are presented as well as information regarding special populations, resistance and drug approval.

Expert opinion: Clinical trial data support the use of peramivir to relieve influenza symptoms in acute, uncomplicated influenza, with improvements over placebo similar to those of other approved anti-influenza treatments. The ability to give a one-time injectable dose offers improved adherence over currently available oral regimens. While not approved for hospitalized patients, available data suggest that multiple dose peramivir may also have a role in treatment of severally ill, hospitalized patients. Supportive data for the use of peramivir in special patient populations such as pediatrics and those especially at-risk to develop severe influenza symptoms are promising; however, they require further study.     

Detection and comparison of neuraminidase activities in human and bovine group B streptococci

Human and bovine group B streptococcus (GBS) isolates were serotyped and amounts of released N‐acetylneuraminic acid from N‐acetylneuraminyl‐lactose by extracellular neuraminidase were colorimetrically assessed. According to serotyping by co‐agglutination method, 30 of bovine GBS and 43 of human GBS could be serotyped (ST) by monospecific antisera coated with protein A. The remaining GBS strains were designated as nontypeable (NT). The released N‐acetylneuraminic acid was determined in 90.9% of bovine GBS and 47.1% of human GBS isolates. The differences between the total bovine and human GBS isolates were statistically significant (p < 0.001). In comparison with detected N‐acetylneuraminic acid level in bovine and human groups, significant decrease was observed in the bovine NT group according to increased human NT (p < 0.01) and bovine ST groups (p < 0.01). However, N‐acetylneuraminic acid level in bovine ST and bovine total groups significantly (p < 0.001) increased with respect to the human ST group and human total group. Neuraminidase activity was detected more frequently in bovine GBS isolates. Considerable differentiations were observed between typeable and nontypeable isolates.