Anti N1 Cross-Protecting Antibodies Against H5N1 Detected in H1N1 Infected People

The A(H5N1) influenza virus pandemic may be the result of avian H5N1 adapting to humans, leading to massive human to human transmission in a context of a lack of pre-existing immunity. As A(H1N1) and A(H5N1) share the same neuraminidase subtype, anti-N1 antibodies subsequent to H1N1 infections or vaccinations may confer some protection against A(H5N1). We analysed, by microneutralization assay, the A/Vietnam/1194/04 (H5N1) anti-N1 cross-protection acquired either during A/NewCaledonia/20/99 (H1N1) infection or vaccination. In cases with documented H1N1 infection, H5N1 cross-protection could be observed only in patients born between 1930 and 1950. No such protection was detected in the sera of vaccinated individuals.     

一种新发现的流感病毒—H5N1

1997年 5月 ,香港首次分离到一种新的Ａ型流感病毒———Ｈ5Ｎ1[1,2 ] ,至该年底共有 18位患者确诊被Ｈ5Ｎ1感染 ,其中 6人死亡[3 ,4 ] 。这是对人类具强毒性的流感病毒新亚型首次被确定。在呼吸系统疾病的病毒中 ,流感病毒因其有抗原性变异而不同于其它病毒 ,特别是它的表面抗原如血凝素 (ｈｅｍａｇｇｌｕｔｉｎｉｎ ,ＨＡ)和神经氨酸酶 (ｎｅｕ ｒａｍｉｎｉｄａｓｅ ,ＮＡ)。主要有两种类型变异 :抗原性漂离(因编码基因点突变的累积导致少量氨基酸改变 )和抗原性转移 (由于不同Ａ型流感病毒亚型的抗原基因的重配引起表面抗原分子广泛的…     

Age-matched comparison of children hospitalized for 2009 pandemic H1N1 influenza with those hospitalized for seasonal H1N1 and H3N2

BACKGROUND: A wide spectrum of clinical manifestation ranging from deaths to a mild course of disease has been reported in children infected with the 2009 pandemic H1N1 (pH1N1) influenza. METHODOLOGY/MAJOR FINDINGS: We conducted an age-matched control study comparing children hospitalized for pH1N1 with historic controls infected with seasonal H1N1 and H3N2 influenza to correct for the effect of age on disease susceptibility and clinical manifestations. We also compared children with pH1N1 to children concurrently admitted for seasonal influenza during the pandemic period to adjust for differences in health-seeking behavior during the pandemic or other potential bias associated with historic controls. There was no death or intensive care admission. Children with pH1N1 were more likely to have at least one risk condition for influenza, an underlying chronic pulmonary condition, more likely to have asthma exacerbation and to be treated with oseltamivir. There was no difference in other aspects of the clinical course or outcome. CONCLUSION: Disease manifestation of children hospitalized for pH1N1 infection was mild in our patient population.     

Prior Infection of Chickens with H1N1 or H1N2 Avian Influenza Elicits Partial Heterologous Protection against Highly Pathogenic H5N1

There is a critical need to have vaccines that can protect against emerging pandemic influenza viruses. Commonly used influenza vaccines are killed whole virus that protect against homologous and not heterologous virus. Using chickens we have explored the possibility of using live low pathogenic avian influenza (LPAI) A/goose/AB/223/2005 H1N1 or A/WBS/MB/325/2006 H1N2 to induce immunity against heterologous highly pathogenic avian influenza (HPAI) A/chicken/Vietnam/14/2005 H5N1. H1N1 and H1N2 replicated in chickens but did not cause clinical disease. Following infection, chickens developed nucleoprotein and H1 specific antibodies, and reduced H5N1 plaque size in vitro in the absence of H5 neutralizing antibodies at 21 days post infection (DPI). In addition, heterologous cell mediated immunity (CMI) was demonstrated by antigen-specific proliferation and IFN-γ secretion in PBMCs re-stimulated with H5N1 antigen. Following H5N1 challenge of both pre-infected and naïve controls chickens housed together, all naïve chickens developed acute disease and died while H1N1 or H1N2 pre-infected chickens had reduced clinical disease and 70–80% survived. H1N1 or H1N2 pre-infected chickens were also challenged with H5N1 and naïve chickens placed in the same room one day later. All pre-infected birds were protected from H5N1 challenge but shed infectious virus to naïve contact chickens. However, disease onset, severity and mortality was reduced and delayed in the naïve contacts compared to directly inoculated naïve controls. These results indicate that prior infection with LPAI virus can generate heterologous protection against HPAI H5N1 in the absence of specific H5 antibody.     

Host Modulators of H1N1 Cytopathogenicity

Influenza A virus infects 5-20% of the population annually, resulting in ～35,000 deaths and significant morbidity. Current treatments include vaccines and drugs that target viral proteins. However, both of these approaches have limitations, as vaccines require yearly development and the rapid evolution of viral proteins gives rise to drug resistance. In consequence additional intervention strategies, that target host factors required for the viral life cycle, are under investigation. Here we employed arrayed whole-genome siRNA screening strategies to identify cell-autonomous molecular components that are subverted to support H1N1 influenza A virus infection of human bronchial epithelial cells. Integration across relevant public data sets exposed druggable gene products required for epithelial cell infection or required for viral proteins to deflect host cell suicide checkpoint activation. Pharmacological inhibition of representative targets, RGGT and CHEK1, resulted in significant protection against infection of human epithelial cells by the A/WS/33 virus. In addition, chemical inhibition of RGGT partially protected against H5N1 and the 2009 H1N1 pandemic strain. The observations reported here thus contribute to an expanding body of studies directed at decoding vulnerabilities in the command and control networks specified by influenza virulence factors.     

Formal kinetics of H1N1 epidemic

Background  

The formal kinetics of the H1N1 epidemic seems to take the form of an exponential curve. There is a good correlation between this theoretical model and epidemiological data on the number of H1N1-infected people. But this formal model leads to paradoxes about the dates when everyone becomes infected: in Mexico this will happen after one year, then in the rest of the world.     

人H7N9禽流感病毒、高致病H5N1禽流感病毒及H1N1流感病毒感染小鼠特征分析

目的对比分析人高致病H5N1禽流感病毒、H7N9禽流感病毒及H1N1流感病毒分别感染BALB/c小鼠后的机体反应特征。方法分别以H7N9病毒、H5N1病毒和H1N1病毒滴鼻感染BALB/c小鼠,观察小鼠存活率、体征变化及感染后肺组织病理损伤差异,检测小鼠感染流感病毒后肺组织增殖细胞核抗原(PCNA)表达并观察小鼠感染后修复状况。结果 H7N9病毒、H5N1病毒和H1N1病毒均感染BALB/c小鼠,小鼠存活率依次为H7N9H1N1H5N1,肺组织病理损伤严重程度依次为H5N1H1N1H7N9,PCNA表达水平依次为H7N9H1N1H5N1。结论 H7N9病毒感染后宿主炎症反应较小,感染后小鼠肺组织自我修复能力较强;H5N1病毒感染BALB/c小鼠后的机体反应最为强烈,感染后恢复能力差,致死率高。     

14N1H and 2H1H cross-relaxation in hydrated proteins.

The frequency dependence of the proton spin-lattice relaxation time T1 of solid hydrated bovine serum albumin and alpha-chymotrypsin has been measured over 4.5 decades in the range 10(4) to 3 X 10(8) Hz mainly by the aid of the field-cycling technique. The comparison between H2O- and D2O-hydrated samples permitted the distinction of exchangeable and unexchangeable protons. In all cases the 14N1H cross-relaxation dips due mainly to the amide groups have been observed. In addition, in the case of the deuterium exchanged proteins a 2H1H quadrupole dip appears. The amide groups act as relaxation sinks due to the coupling of the amide proton to 14N and adjacent protons. Outside of the dip regions the proton-proton coupling dominates. The fluctuations of the 14N1H and 1H1H interactions are of a different type. The unexchangeable protons show a T1 dispersion outside of the quadrupole dip regions given by the exceptional power law T1 approximately v0.75 +/- 0.05. It is shown that apart from structural information of the 14N spectra, 14N1H cross-relaxation spectroscopy permits the determination of correlation times in the range 10(-7) s less than tau less than 10(-4)S.     

Comparative analyses of pandemic H1N1 and seasonal H1N1, H3N2, and influenza B infections depict distinct clinical pictures in ferrets

Influenza A and B infections are a worldwide health concern to both humans and animals. High genetic evolution rates of the influenza virus allow the constant emergence of new strains and cause illness variation. Since human influenza infections are often complicated by secondary factors such as age and underlying medical conditions, strain or subtype specific clinical features are difficult to assess. Here we infected ferrets with 13 currently circulating influenza strains (including strains of pandemic 2009 H1N1 [H1N1pdm] and seasonal A/H1N1, A/H3N2, and B viruses). The clinical parameters were measured daily for 14 days in stable environmental conditions to compare clinical characteristics. We found that H1N1pdm strains had a more severe physiological impact than all season strains where pandemic A/California/07/2009 was the most clinically pathogenic pandemic strain. The most serious illness among seasonal A/H1N1 and A/H3N2 groups was caused by A/Solomon Islands/03/2006 and A/Perth/16/2009, respectively. Among the 13 studied strains, B/Hubei-Wujiagang/158/2009 presented the mildest clinical symptoms. We have also discovered that disease severity (by clinical illness and histopathology) correlated with influenza specific antibody response but not viral replication in the upper respiratory tract. H1N1pdm induced the highest and most rapid antibody response followed by seasonal A/H3N2, seasonal A/H1N1 and seasonal influenza B (with B/Hubei-Wujiagang/158/2009 inducing the weakest response). Our study is the first to compare the clinical features of multiple circulating influenza strains in ferrets. These findings will help to characterize the clinical pictures of specific influenza strains as well as give insights into the development and administration of appropriate influenza therapeutics.     

Pathogenesis and transmission of triple-reassortant swine H1N1 influenza viruses isolated before the 2009 H1N1 pandemic

The 2009 H1N1 pandemic influenza virus represents the greatest incidence of human infection with an influenza virus of swine origin to date. Moreover, triple-reassortant swine (TRS) H1N1 viruses, which share similar host and lineage origins with 2009 H1N1 viruses, have been responsible for sporadic human cases since 2005. Similar to 2009 H1N1 viruses, TRS viruses are capable of causing severe disease in previously healthy individuals and frequently manifest with gastrointestinal symptoms; however, their ability to cause severe disease has not been extensively studied. Here, we evaluated the pathogenicity and transmissibility of two TRS viruses associated with disease in humans in the ferret model. TRS and 2009 H1N1 viruses exhibited comparable viral titers and histopathologies following virus infection and were similarly unable to transmit efficiently via respiratory droplets in the ferret model. Utilizing TRS and 2009 H1N1 viruses, we conducted extensive hematologic and blood serum analyses on infected ferrets to identify lymphohematopoietic parameters associated with mild to severe influenza virus infection. Following H1N1 or H5N1 influenza virus infection, ferrets were found to recapitulate several laboratory abnormalities previously documented with human disease, furthering the utility of the ferret model for the assessment of influenza virus pathogenicity.     

Complex patterns of human antisera reactivity to novel 2009 H1N1 and historical H1N1 influenza strains

Background

During the 2009 influenza pandemic, individuals over the age of 60 had the lowest incidence of infection with approximately 25% of these people having pre-existing, cross-reactive antibodies to novel 2009 H1N1 influenza isolates. It was proposed that older people had pre-existing antibodies induced by previous 1918-like virus infection(s) that cross-reacted to novel H1N1 strains.

Methodology/Principal Findings

Using antisera collected from a cohort of individuals collected before the second wave of novel H1N1 infections, only a minority of individuals with 1918 influenza specific antibodies also demonstrated hemagglutination-inhibition activity against the novel H1N1 influenza. In this study, we examined human antisera collected from individuals that ranged between the ages of 1 month and 90 years to determine the profile of seropositive influenza immunity to viruses representing H1N1 antigenic eras over the past 100 years. Even though HAI titers to novel 2009 H1N1 and the 1918 H1N1 influenza viruses were positively associated, the association was far from perfect, particularly for the older and younger age groups.

Conclusions/Significance

Therefore, there may be a complex set of immune responses that are retained in people infected with seasonal H1N1 that can contribute to the reduced rates of H1N1 influenza infection in older populations.     

Increased pathogenicity of a reassortant 2009 pandemic H1N1 influenza virus containing an H5N1 hemagglutinin

A novel H1N1 influenza virus emerged in 2009 (pH1N1) to become the first influenza pandemic of the 21st century. This virus is now cocirculating with highly pathogenic H5N1 avian influenza viruses in many parts of the world, raising concerns that a reassortment event may lead to highly pathogenic influenza strains with the capacity to infect humans more readily and cause severe disease. To investigate the virulence of pH1N1-H5N1 reassortant viruses, we created pH1N1 (A/California/04/2009) viruses expressing individual genes from an avian H5N1 influenza strain (A/Hong Kong/483/1997). Using several in vitro models of virus replication, we observed increased replication for a reassortant CA/09 virus expressing the hemagglutinin (HA) gene of HK/483 (CA/09-483HA) relative to that of either parental CA/09 virus or reassortant CA/09 expressing other HK/483 genes. This increased replication correlated with enhanced pathogenicity in infected mice similar to that of the parental HK/483 strain. The serial passage of the CA/09 parental virus and the CA/09-483HA virus through primary human lung epithelial cells resulted in increased pathogenicity, suggesting that these viruses easily adapt to humans and become more virulent. In contrast, serial passage attenuated the parental HK/483 virus in vitro and resulted in slightly reduced morbidity in vivo, suggesting that sustained replication in humans attenuates H5N1 avian influenza viruses. Taken together, these data suggest that reassortment between cocirculating human pH1N1 and avian H5N1 influenza strains will result in a virus with the potential for increased pathogenicity in mammals.     

Dendritic Cell Activation by Recombinant Hemagglutinin Proteins of H1N1 and H5N1 Influenza A Viruses

Since dendritic cells may play a key role in defense against influenza virus infection, we examined the effects of recombinant hemagglutinin (HA) proteins derived from mouse-adapted H1N1 (A/WSN/1933), swine-origin 2009 pandemic H1N1 (A/Texas/05/2009), and highly pathogenic avian influenza H5N1 (A/Thailand/KAN-1/2004) viruses on mouse myeloid dendritic cells (mDCs). The results reveal that tumor necrosis factor alpha (TNF-α), interleukin-12 (IL-12) p70, and major histocompatibility complex class II (MHC-II) expression was increased in mDCs after treatment with recombinant HA proteins of H1N1 and H5N1. The specificity of recombinant HA treatments for mDC activation was diminished after proteinase K digestion. HA apparently promotes mDC maturation by enhancing CD40 and CD86 expression and suppressing endocytosis. No significant differences in mDC activation were observed among recombinant proteins of H1N1 and H5N1. The stimulation of mDCs by HA proteins of H1N1 and H5N1 was completely MyD88 dependent. These findings may provide useful information for the development of more-effective influenza vaccines.Influenza viruses trigger seasonal epidemics or pandemics of contagious diseases with mild to severe consequences in human and poultry populations worldwide (28). Members of the Orthomyxoviridae family, influenza viruses consist of single-stranded, eight-segment, negative-sense genomic RNAs, helical viral ribonucleoprotein (RNP) complexes (RNA segments, NP, PB2, PB1, and PA) and four viral envelope proteins (hemagglutinin [HA], neuraminidase [NA], and M1 and M2 matrix proteins). Type A influenza viruses are further classified into various serotypes based on the antigenic characteristics of HA and NA glycoproteins (14).In 2009, a swine-origin H1N1 strain emerged from the genetic reassortants of existing human, avian, and swine influenza viruses, resulting in a global pandemic marked by symptoms more severe than those associated with seasonal influenza virus (3, 24). According to comparative pathology in macaque monkeys, H5N1 induces greater cytokinemia, tissue damage, and interference with immune regulatory mechanisms than H1N1 infection (2). The HA spike protein of influenza virus is believed to play important roles in viral receptor binding, fusion, transmission, host range restriction, virulence, and pathogenesis (13, 27-30).Dendritic cells (DCs), considered the most potent professional antigen-presenting cells, serve as links between innate and adaptive immunity (31). Upon encountering microbial pathogens, endogenous danger signals, or inflammatory mediators, DCs mature and elicit rapid and short-lived innate immune responses before migrating to secondary lymphoid organs and enhancing adaptive immunity (17). Two major subsets of DCs are recognized in mice and humans: (i) myeloid DCs (mDCs, also called conventional DCs), which participate most directly in antigen presentation and activation of naïve T cells, and (ii) plasmacytoid DCs (pDCs), which produce type I interferons in response to viral infection (16, 42) and are also capable of inducing immunotolerance under some conditions (9). mDCs and pDCs also comprise different heterologous subsets, with unique localizations, phenotypes, and functions (36). Due to their key role in immune regulation, DCs have been developed for immunotherapeutic agents or prophylactic or therapeutic vaccines for cancer, infectious diseases, and immune system-related diseases (32, 34).DCs are essential in controlling the innate and adaptive immune responses against influenza virus infection (21). Viral RNA is recognized by various pattern recognition receptors (PRRs), including RIG-I-like receptors (RLRs), Toll-like receptors (TLRs), and nucleotide oligomerization domain (NOD)-like receptors (NLRs). TLRs play an especially important role in detecting virus invasion and activating DCs (18, 35). However, the mechanisms causing DC activation and maturation in response to influenza viruses are not clear. HA has been described as playing an important role in modulating influenza virus virulence and host immune responses (29). In this study, we examined the effects of several recombinant HA proteins (rHAs) derived from rHA of H1N1 (rH1HA) (A/WSN/1933) and (A/Texas/05/2009) and rHA of H5N1 (rH5HA) (A/Thailand/KAN-1/2004) viruses on the activation and maturation of the mDC subset derived from mouse bone marrow.     

Single-dose mucosal immunization with a candidate universal influenza vaccine provides rapid protection from virulent H5N1, H3N2 and H1N1 viruses

Background

The sudden emergence of novel influenza viruses is a global public health concern. Conventional influenza vaccines targeting the highly variable surface glycoproteins hemagglutinin and neuraminidase must antigenically match the emerging strain to be effective. In contrast, “universal” vaccines targeting conserved viral components could be used regardless of viral strain or subtype. Previous approaches to universal vaccination have required protracted multi-dose immunizations. Here we evaluate a single dose universal vaccine strategy using recombinant adenoviruses (rAd) expressing the conserved influenza virus antigens matrix 2 and nucleoprotein.

Methodology/Principal Findings

In BALB/c mice, administration of rAd via the intranasal route was superior to intramuscular immunization for induction of mucosal responses and for protection against highly virulent H1N1, H3N2, or H5N1 influenza virus challenge. Mucosally vaccinated mice not only survived, but had little morbidity and reduced lung virus titers. Protection was observed as early as 2 weeks post-immunization, and lasted at least 10 months, as did antibodies and lung T cells with activated phenotypes. Virus-specific IgA correlated with but was not essential for protection, as demonstrated in studies with IgA-deficient animals.

Conclusion/Significance

Mucosal administration of NP and M2-expressing rAd vectors provided rapid and lasting protection from influenza viruses in a subtype-independent manner. Such vaccines could be used in the interval between emergence of a new virus strain and availability of strain-matched vaccines against it. This strikingly effective single-dose vaccination thus represents a candidate off-the-shelf vaccine for emergency use during an influenza pandemic.