Erster Erfahrungsaustausch zur H1N1-Pandemie in Deutschland 2009/2010

In April 2009 the first pandemic of the 21st century developed within a few weeks starting from Mexico. Its first wave reached Germany in autumn 2009 and was responsible for 1.8–3.5 million additional medical consultations. For the public health sector, this pandemic was one of the largest challenges of the last few decades. As a contribution to broader evaluations on national and international level, the Robert Koch Institute invited representatives from different professions involved in the pandemic response to participate in a workshop on 22–23 March 2010. This workshop was structured in short presentations, group work, and plenary discussions. Main experiences were that (a) pandemic preparedness was helpful, (b) the early warning systems were reliable, (c) vaccines were available within a few months, however, in limited amounts. Need for improvement was discussed for (a) effectiveness of vaccination logistics, (b) mechanisms for the reimbursement of the cost of vaccination, (c) availability of surveillance and monitoring systems, (d) integration of physicians in decision-making processes and health education, and (e) proactive communication strategies. Investments in the above mentioned areas can help to improve public health protection in the future.     

H1N1 vaccination

Early results (January to April) from the 2010 Canadian Community Health Survey show that an estimated 41% of Canadians (excluding those in the territories) aged 12 or older had been vaccinated for H1N1 by April 2010. The percentages were higher in the Atlantic provinces, Quebec and Saskatchewan than in Canada overall. Relatively high percentages of females and people aged 45 or older were vaccinated; the percentage of immigrants who had done so was relatively low. Being in a priority group (health-care worker, having children younger than 5 in the household, or having a chronic condition that could increase the risk for complications from H1N1) increased the likelihood of vaccination. A history of seasonal flu vaccination and having a regular doctor were also associated with H1N1 vaccination. Nearly three-quarters of those who had not been vaccinated reported that they did not think it was necessary.     

Protective efficacy of an inactivated Eurasian avian-like H1N1 swine influenza vaccine against homologous H1N1 and heterologous H1N1 and H1N2 viruses in mice

Eurasian avian-like H1N1 (EA H1N1) swine influenza viruses are prevalent in pigs in Europe and Asia, but occasionally cause human infection, which raises concern about their pandemic potential. Here, we produced a whole-virus inactivated vaccine with an EA H1N1 strain (A/swine/Guangxi/18/2011, SW/GX/18/11) and evaluated its efficacy against homologous H1N1 and heterologous H1N1 and H1N2 influenza viruses in mice. A strong humoral immune response, which we measured by hemagglutination inhibition (HI) and virus neutralization (VN), was induced in the vaccine-inoculated mice upon challenge. The inactivated SW/GX/18/11 vaccine provided complete protection against challenge with homologous SW/GX/18/11 virus in mice and provided effective protection against challenge with heterologous H1N1 and H1N2 viruses with distinctive genomic combinations. Our findings suggest that this EA H1N1 vaccine can provide protection against both homologous H1N1 and heterologous H1N1 or H1N2 virus infection. As such, it is an excellent vaccine candidate to prevent H1N1 swine influenza.     

接种甲型H1N1流感疫苗后患甲型H1N1流感分析

目的 分析接种甲型H1N1流感疫苗后发生甲型H1N1流感感染的病例,探讨发病原因,为进一步提高疫苗预防效果提供参考依据.方法 对接种甲型H1N1流感疫苗后发生甲型H1N1流感感染148例,进行回顾性调查分析.结果 接种甲型H1N1流感疫苗11176例.发生甲型H1N1感染148例,感染率1.32%,其中1～14 d感染81例,感染率0.72%,＞15 d感染67例,感染率0.60%.结论 甲型H1N1流感病毒裂解疫苗是一种安全高效的疫苗,不足之处尚待进一步探讨、完善.     

Co-circulation of pandemic 2009 H1N1, classical swine H1N1 and avian-like swine H1N1 influenza viruses in pigs in China

The pandemic A/H1N1 influenza viruses emerged in both Mexico and the United States in March 2009, and were transmitted efficiently in the human population. They were transmitted occasionally from humans to other mammals including pigs, dogs and cats. In this study, we report the isolation and genetic analysis of novel viruses in pigs in China. These viruses were related phylogenetically to the pandemic 2009 H1N1 influenza viruses isolated from humans and pigs, which indicates that the pandemic virus is currently circulating in swine populations, and this hypothesis was further supported by serological surveillance of pig sera collected within the same period. Furthermore, we isolated another two H1N1 viruses belonging to the lineages of classical swine H1N1 virus and avian-like swine H1N1 virus, respectively. Multiple genetic lineages of H1N1 viruses are co-circulating in the swine population, which highlights the importance of intensive surveillance for swine influenza in China.     

H1N1 influenza is here

On 11 June WHO announced that the spread of H1N1 had reached pandemic phase 6. Since then countries around the world have increased their planning and preparedness for the continuing pandemic. Guidelines have been issued and circulated but confusion continues over their interpretation. We need to remind ourselves of the principles behind control measures and educate and reinforce standard infection control procedures in the acute hospital setting.     

Influenza A Strain-Dependent Pathogenesis in Fatal H1N1 and H5N1 Subtype Infections of Mice

To determine if fatal infections caused by different highly virulent influenza A viruses share the same pathogenesis, we compared 2 different influenza A virus subtypes, H1N1 and H5N1. The subtypes, which had shown no pathogenicity in laboratory mice, were forced to evolve by serial passaging. Although both adapted viruses evoked diffuse alveolar damage and showed a similar 50% mouse lethal dose and the same peak lung concentration, each had a distinct pathologic signature and caused a different course of acute respiratory distress syndrome. In the absence of any virus labeling, a histologist could readily distinguish infections caused by these 2 viruses. The different histologic features described in this study here refute the hypothesis of a single, universal cytokine storm underlying all fatal influenza diseases. Research is thus crucially needed to identify sets of virulence markers and to examine whether treatment should be tailored to the influenza virus pathotype.     

Development of broadly reactive H5N1 vaccine against different Egyptian H5N1 viruses

The H5N1 highly pathogenic avian influenza (HPAI) virus was isolated for the first time in Egypt in 2006, since then, the virus has become endemic causing a significant threat to the poultry industry and humans. H5N1 HPAI outbreaks continue to occur despite extensive vaccination programs that have been implemented nationwide in different poultry species. Several studies showed that the co-circulating H5N1 viruses in Egypt are genetically and antigenically distant raising a question on the cross protective efficacy of commercial vaccines. In this study, we introduced mutations at the antigenic sites of the hemagglutinin (HA) to broaden reactivity of the Egyptian H5N1 virus. A reverse genetically created variant H5N1 virus (A/chicken/Egypt/1063/2010) with five amino acid mutations (G140R, Y144F, I190L, K192Q, D43N) in the HA gene showed enhanced cross reactivity. This virus showed up to 16 fold increase in reactivity to the classic-lineageH5N1viruses measured by hemagglutination inhibition (HI) assay while maintaining similar level of reactivity with the variant-lineage viruses compared to wild-type virus. In addition, a single amino acid substitution (N165H), which removes potential glycosylation site at the HA globular head of two classic strains (A/chicken/Egypt/527/2012 and A/chicken/Egypt/102d/2010) broadened the reactivity to antisera generated against H5N1 viruses from different clusters. The broadened reactivity of the mutant viruses were also confirmed by testing reactivity of antisera prepared from the mutant viruses against reference viruses from both classic and variant clades. The virus neutralization test using selected antisera and viruses further confirmed the cross HI results. This study highlights that targeted mutation in the HA may be effectively used as a tool to develop broadly reactive influenza vaccines to cope with the continuous antigenic evolution of viruses.     

一起甲型H1N1和H3N2流感病毒混合感染调查研究

目的 从病例临床特征、抗体变化规律及病原学检测等多角度分析一起由甲型H1N1和H3N2流感病毒混合感染引起暴发疫情的流行特征,为有效控制疾病的发生与蔓延提供科学依据.方法 采用回顾性调查和现场流行病学调查方法进行问卷调查,利用RT-PCR和血凝抑制试验分别进行流感病毒和血清抗体检测.结果 45例流感样病例中,确诊40例,其中22例为甲型H1N1流感、12例为季节性H3N2型流感、6例为H1N1和H3N2病毒混合感染.不同病毒感染病例的临床表现差异无统计学意义.序列比对分析显示,混合病毒感染和单一病毒感染者的甲型H1N1和季节性H3N2病毒基因序列没有差异.同时分析表明,所有流感病例的病毒株均对金刚烷胺耐药,对奥司他韦(达菲)有效.患者的双份血清血凝抑制试验检测表明,暴发由甲型H1N1和H3N2流感病毒混合感染引起.结论 这是一起由甲型H1N1和H3N2流感病毒混合感染引起的疫情,甲型H1N1病毒在传播过程中可能较H3N2更具有优势.     

Protection against a European H1N2 swine influenza virus in pigs previously infected with H1N1 and/or H3N2 subtypes

A novel swine influenza virus, H1N2, circulates in European swine populations together with H1N1 and H3N2 viruses. This study examines whether post-infection immunity to H1N1 and/or H3N2 viruses provides cross-protection against H1N2 infection. Pigs (n=51) were inoculated intranasally with either Sw/Belgium/1/98 (H1N1) or Sw/Flanders/1/98 (H3N2), or with both viruses at a 5-week interval. Control groups were left uninoculated or inoculated with Sw/Gent/7625/99 (H1N2). Four weeks later, all the pigs were challenged intranasally and intratracheally with a high H1N2 virus dose. The challenge control pigs showed typical influenza symptoms, and all had high H1N2 virus titres in the lungs and nasal virus excretion during 6 or 7 days. The H1N2-immune pigs showed total clinical and virological protection. Pigs immune against H1N1 or H3N2 only were not protected against disease and virus replication in the lungs, but virus excretion was 2 days shorter. By contrast, pigs immune against both H1N1 and H3N2 did not show disease and H1N2 virus replication was either undetectable or markedly reduced. Haemagglutination inhibition (HI) and virus neutralisation (VN) tests indicated that cross-protection against H1N2 was probably not mediated by antibodies against the haemagglutinin (HA). Antibodies inhibiting the neuraminidase (NA) of H1N2 were at minimal levels in H3N2 only-immune pigs, but they were consistently found in (H1N1+H3N2)-immune pigs. The immune response against the internal proteins, which are relatively conserved in H1N1, H3N2 and H1N2 viruses, may play a significant role in protection against H1N2. Given the severe challenge model used here, cross-protection against H1N2 could be more pronounced under natural conditions of infection.     

Vaccination with virus-like particles containing H5 antigens from three H5N1 clades protects chickens from H5N1 and H5N8 influenza viruses

Highly pathogenic avian influenza (HPAI) viruses, especially H5N1 strains, represent a public health threat and cause widespread morbidity and mortality in domestic poultry. Recombinant virus-like particles (VLPs) represent a promising novel vaccine approach to control avian influenza including HPAI strains. Influenza VLPs contain viral hemagglutinin (HA), which can be expressed in cell culture within highly immunogenic VLPs that morphologically and antigenically resemble influenza virions, except VLPs are non-infectious. Here we describe a recombinant VLP containing HA proteins derived from three distinct clades of H5N1 viruses as an experimental, broadly protective H5 avian influenza vaccine. A baculovirus vector was configured to co-express the H5 genes from recent H5N1 HPAI isolates A/chicken/Germany/2014 (clade 2.3.4.4), A/chicken/West Java/Subang/29/2007 (clade 2.1.3) and A/chicken/Egypt/121/2012 (clade 2.2.1). Co-expression of these genes in Sf9 cells along with influenza neuraminidase (NA) and retrovirus gag genes resulted in production of triple-clade H555 VLPs that exhibited hemagglutination activity and morphologically resembled influenza virions. Vaccination of chickens with these VLPs resulted in induction of serum antibody responses and efficient protection against experimental challenges with three different viruses including the recent U.S. H5N8 HPAI isolate. We conclude that these novel triple-clade VLPs represent a feasible strategy for simultaneously evoking protective antibodies against multiple variants of H5 influenza virus.     

Das pandemische H1N1-Influenzavirus/2009

The generation of pandemic influenza A viruses of the previous century as well as that of the current influenza A/H1N1/2009 pandemic appear to be governed and preceded by reassortment events in other mammalian species. So far, it could not be shown that transmission of avian influenza viruses to humans will directly cause a pandemic. Zoonotic transmissions of avian and also of porcine influenza viruses of diverse subtypes have been repeatedly described. However, these events did not lead to further spread and establishment of these viruses. This is in contrast to the current A/H1N1/2009 viruses which already have started to outcompete seasonal human influenza viruses. The actual molecular key factors required for a successful exchange of genome segments between different influenza virus strains and which factors foster the consecutive spread of certain reassortant viruses in the human population remain to be pinpointed. It has been elucidated so far that newly introduced genome segments need to be compatible with both the remaining original segments and the human hosts.     

H1N1流感爆发带来的启示

H1N1流感最早爆发于墨西哥和美国,感染该病患者会出现上呼吸道症状,随后在世界其他国家也相继出现确诊病例。病原产生的环境、促使跨种传播的因素仍未彻底明了,但可以明确的是在疾病爆发的早期,该病毒就能够直接在人间传播。来源于动物宿主的病原不断地获得在人间传播的潜能,进而导致疾病爆发的事件贯穿人类历史。虽然每次爆发都有其各自特点,但是关键的是要从以往的流行事件中获得启示。把以往防控的经验教训进行整合,从而进一步了解宿主／病原相互作用,采取强有力的预防和治疗措施。