Pandemic influenza 1918 H1N1 and 1968 H3N2 DNA vaccines induce cross-reactive immunity in ferrets against infection with viruses drifted for decades

Please cite this paper as: Bragstad et al. (2010) Pandemic influenza 1918 H1N1 and 1968 H3N2 DNA vaccines induce cross‐reactive immunity in ferrets against infection with viruses drifted for decades. Influenza and Other Respiratory Viruses 5(1), 13–23. Background Alternative influenza vaccines and vaccine production forms are needed as the conventional protein vaccines do not induce broad cross‐reactivity against drifted strains. Furthermore, fast vaccine production is especially important in a pandemic situation, and broader vaccine reactivity would diminish the need for frequent change in the vaccine formulations. Objective In this study, we compared the ability of pandemic influenza DNA vaccines to induce immunity against distantly related strains within a subtype with the immunity induced by conventional trivalent protein vaccines against homologous virus challenge. Methods Ferrets were immunised by particle‐mediated epidermal delivery (gene gun) with DNA vaccines based on the haemagglutinin (HA) and neuraminidase (NA) and/or the matrix (M) and nucleoprotein genes of the 1918 H1N1 Spanish influenza pandemic virus or the 1968 H3N2 Hong Kong influenza pandemic virus. The animals were challenged with contemporary H1N1 or H3N2 viruses. Results We demonstrated that DNA vaccines encoding proteins of the original 1918 H1N1 pandemic virus induced protective cross‐reactive immune responses in ferrets against infection with a 1947 H1N1 virus and a recent 1999 H1N1 virus. Similarly, a DNA vaccine, based on the HA and NA of the 1968 H3N2 pandemic virus, induced cross‐reactive immune responses against a recent 2005 H3N2 virus challenge. Conclusions DNA vaccines based on pandemic or recent seasonal influenza genes induced cross‐reactive immunity against contemporary virus challenge as good as or superior to contemporary conventional trivalent protein vaccines. This suggests a unique ability of influenza DNA to induce cross‐protective immunity against both contemporary and long‐time drifted viruses.     

A plant‐produced influenza subunit vaccine protects ferrets against virus challenge

Background Influenza A viruses are of major concern for public health, causing worldwide epidemics associated with high morbidity and mortality. Vaccines are critical for protection against influenza, but given the recent emergence of new strains with pandemic potential, and some limitations of the current production systems, there is a need for new approaches for vaccine development. Objective To demonstrate the immunogenicity and protective efficacy of plant‐produced influenza antigens. Method We engineered, using influenza A/Wyoming/3/03 (H3N2) as a model virus, the stem and globular domains of hemagglutinin (HA) produced in plants as fusions to a carrier protein and used purified antigens with and without adjuvant for ferret immunization. Results These plant‐produced antigens were highly immunogenic and conferred complete protection against infection in the ferret challenge model. The addition of plant‐produced neuraminidase was shown to enhance the immune response in ferrets. Conclusions Plants can be used as a production vehicle for vaccine development against influenza. Domains of HA can generate protective immune responses in ferrets.     

Rapid generation of pandemic influenza virus vaccine candidate strains using synthetic DNA

Please cite this paper as: Verity et al. (2011) Rapid generation of pandemic influenza virus vaccine candidate strains using synthetic DNA. Influenza and Other Respiratory Viruses DOI:10.1111/j.1750‐2659.2011.00273.x. Background Vaccination is considered the most effective means of reducing influenza burden. The emergence of H5N1 and pandemic spread of novel H1N1/2009 viruses reinforces the need to have strategies in place to rapidly develop seed viruses for vaccine manufacture. Methods Candidate pandemic vaccine strains consisting of the circulating strain haemagglutinin (HA) and neuraminidase (NA) in an A/PR/8/34 backbone were generated using alternative synthetic DNA approaches, including site‐directed mutagenesis of DNA encoding related virus strains, and rapid generation of virus using synthetic DNA cloned into plasmid vectors. Results Firstly, synthetic A/Bar Headed Goose/Qinghai/1A/2005 (H5N1) virus was generated from an A/Vietnam/1194/2004 template using site‐directed mutagenesis. Secondly, A/Whooper Swan/Mongolia/244/2005 (H5N1) and A/California/04/09 (H1N1) viruses were generated using synthetic DNA encoding the viral HA and NA genes. Replication and antigenicity of the synthetic viruses were comparable to that of the corresponding non‐synthetic viruses. Conclusions In the event of an influenza pandemic, the use of these approaches may significantly reduce the time required to generate and distribute the vaccine seed virus and vaccine manufacture. These approaches also offer the advantage of not needing to handle wild‐type virus, potentially diminishing biocontainment requirements.     

Determination of H5N1 vaccine potency using reference antisera from heterologous strains of influenza

Please cite this paper as: Vodeiko and Weir (2011). Determination of H5N1 vaccine potency using reference antisera from heterologous strains of influenza. Influenza and Other Respiratory Viruses 6(3), 176–187. Background Standardization of inactivated influenza vaccines by hemagglutinin (HA) content is performed by the single radial immunodiffusion (SRID) method. Regulatory agencies prepare, calibrate, and distribute SRID reagent standards necessary for testing of seasonal influenza vaccines, and a similar process is used to produce potency reagents for candidate pandemic influenza vaccines that are manufactured for emergency stockpiles. Objectives Because of the concerns in generating a timely strain‐specific potency antiserum for an emerging pandemic virus, we evaluated the feasibility of using heterologous potency reference antiserum as a replacement for a strain‐specific (homologous) antiserum in the SRID potency assay for stockpiled H5N1 vaccines. Results The results indicate that a heterologous H5N1 antiserum can be used to determine the accurate potency of inactivated H5N1 influenza vaccines. Additionally, when H5N1 vaccine was subjected to an accelerated stability protocol, both homologous and heterologous antisera provided similar measurements of vaccine potency decline. Limitations to the heterologous antiserum approach to potency determination were shown by the inability of antiserum to recent seasonal H1N1 viruses to work in an SRID assay with the 2009 pandemic H1N1 A/California/07/2009 antigen. Conclusions The data demonstrate the feasibility of using heterologous antiserum for potency determination of at least some candidate vaccines in case of a shortage or delay of homologous antiserum. Further, the results suggest the prudence of stockpiling a broad library of potency reagents including many strains of influenza viruses with pandemic potential to provide an added measure of assurance that reagent production would not be a bottleneck to vaccine production during a pandemic.     

Comparative safety, immunogenicity, and efficacy of several anti-H5N1 influenza experimental vaccines in a mouse and chicken models (Testing of killed and live H5 vaccine)

Please cite this paper as: Gambaryan et al. (2011) Comparative safety, immunogenicity, and efficacy of several anti‐H5N1 influenza experimental vaccines in a mouse and chicken models. Parallel testing of killed and live H5 vaccine. Influenza and Other Respiratory Viruses 6(3), 188–195. Objective Parallel testing of inactivated (split and whole virion) and live vaccine was conducted to compare the immunogenicity and protective efficacy against homologous and heterosubtypic challenge by H5N1 highly pathogenic avian influenza virus. Method Four experimental live vaccines based on two H5N1 influenza virus strains were tested; two of them had hemagglutinin (HA) of A/Vietnam/1203/04 strain lacking the polybasic HA cleavage site, and two others had hemagglutinins from attenuated H5N1 virus A/Chicken/Kurgan/3/05, with amino acid substitutions of Asp54/Asn and Lys222/Thr in HA1 and Val48/Ile and Lys131/Thr in HA2 while maintaining the polybasic HA cleavage site. The neuraminidase and non‐glycoprotein genes of the experimental live vaccines were from H2N2 cold‐adapted master strain A/Leningrad/134/17/57 (VN‐Len and Ku‐Len) or from the apathogenic H6N2 virus A/Gull/Moscow/3100/2006 (VN‐Gull and Ku‐Gull). Inactivated H5N1 and H1N1 and live H1N1 vaccine were used for comparison. All vaccines were applied in a single dose. Safety, immunogenicity, and protectivity against the challenge with HPAI H5N1 virus A/Chicken/Kurgan/3/05 were estimated. Results All experimental live H5 vaccines tested were apathogenic as determined by weight loss and conferred more than 90% protection against lethal challenge with A/Chicken/Kurgan/3/05 infection. Inactivated H1N1 vaccine in mice offered no protection against challenge with H5N1 virus, while live cold‐adapted H1N1 vaccine reduced the mortality near to zero level. Conclusions The high yield, safety, and protectivity of VN‐Len and Ku‐Len made them promising strains for the production of inactivated and live vaccines against H5N1 viruses.     

2019-2020年海南省A(H1N1)pdm09 流感病毒基因特性分析

目的 分析海南省A(H1N1) pdm09亚型流感病毒的抗原性和基因特性,了解病毒的变异情况,为海南省A(H1N1)pdm09亚型流感病毒的防控提供依据.方法 选取14株2019-2020年海南省流感监测网络实验室分离到的A(H1N1)pdm09亚型流感病毒进行基因序列测定,测序结果用MEGA 10.1.8和DNAST...     

Antibody responses against influenza A(H1N1)pdm09 virus after sequential vaccination with pandemic and seasonal influenza vaccines in Finnish healthcare professionals

Background Influenza A(H1N1)pdm09 virus has been circulating in human population for three epidemic seasons. During this time, monovalent pandemic and trivalent seasonal influenza vaccination against this virus have been offered to Finnish healthcare professionals. It is, however, unclear how well vaccine‐induced antibodies recognize different strains of influenza A(H1N1)pdm09 circulating in the population and whether the booster vaccination with seasonal influenza vaccine would broaden the antibody cross‐reactivity. Objectives Influenza vaccine‐induced humoral immunity against several isolates of influenza A(H1N1)pdm09 virus was analyzed in healthcare professionals. Age‐dependent responses were also analyzed. Methods Influenza viruses were selected to represent viruses that circulated in Finland during two consecutive influenza epidemic seasons 2009–2010 and 2010–2011. Serum samples from vaccinated volunteers, age 20–64 years, were collected before and after vaccination with AS03‐adjuvanted pandemic and non‐adjuvanted trivalent seasonal influenza vaccine that was given 1 year later. Results Single dose of pandemic vaccine induced a good albeit variable antibody response. On day 21 after vaccination, depending on the virus strain, 14–75% of vaccinated had reached antibody titers (≥1:40) considered seroprotective. The booster vaccination 1 year later with a seasonal vaccine elevated the seroprotection rate to 57–98%. After primary immunization, younger individuals (20–48 years) had significantly higher antibody titers against all tested viruses than older persons (49–64 years) but this difference disappeared after the seasonal booster vaccination. Conclusions Even a few amino acid changes in influenza A HA may compromise the vaccine‐induced antibody recognition. Older adults (49 years and older) may benefit more from repeated influenza vaccinations.     

Label‐free mass spectrometry‐based quantification of hemagglutinin and neuraminidase in influenza virus preparations and vaccines

Please cite this paper as: Getie‐Kebtie et al. (2012) Label‐free mass spectrometry‐based quantification of hemagglutinin and neuraminidase in influenza virus preparations and vaccines. Influenza and Other Respiratory Viruses 7(4), 521–530. Background Influenza vaccination is the primary method for preventing influenza and its severe complications. An accurate rapid method to determine hemagglutinin (HA) concentration would facilitate reference antigen preparation and consequently expedite availability of seasonal as well as pandemic vaccines. Objective The goal of this study was to develop a label‐free mass spectrometry (MS) based method that enables simultaneous identification and quantification of HA, neuraminidase (NA), and other viral proteins and protein contaminations in influenza vaccine or virus preparations. Methods The method presented is based on LC/MSE analysis of vaccine or virus preparations tryptic digests spiked with a known amount of protein standard from which a universal response factor is generated and applied to calculate the concentration of proteins identified in the mixture. Results We show that, with the use of an appropriate internal standard, the label‐free MS‐based protein quantification method is applicable for simultaneous identification and absolute quantification of HA and identification and relative quantification of other influenza proteins as well as protein impurities in influenza vaccines and virus preparations. We show that different subtype recombinant HA is preferred internal standard that provides the most accurate results in absolute quantification of HAs and other influenza proteins. We applied this method to measure the absolute quantity of HA as well as relative quantities of other viral proteins and impurities in preparations of whole virus and monovalent vaccine, providing data to demonstrate strain‐dependent differences in the amount of NA. Conclusion The label‐free MS method presented here is ideally suited for timely preparation of reference material needed for potency testing of seasonal and pandemic vaccines.     

Long‐term vaccine‐induced heterologous protection against H5N1 influenza viruses in the ferret model

Please cite this paper as: Ducatez et al. (2012) Long‐term vaccine‐induced heterologous protection against H5N1 influenza viruses in the ferret model. Influenza and Other Respiratory Viruses 7(4), 506–512. Background Highly pathogenic H5N1 influenza viruses reemerged in humans in 2003 and have caused fatal human infections in Asia and Africa as well as ongoing outbreaks in poultry. These viruses have evolved substantially and are now so antigenically varied that a single vaccine antigen may not protect against all circulating strains. Nevertheless, studies have shown that substantial cross‐reactivity can be achieved with H5N1 vaccines. These studies have not, however, addressed the issue of duration of such cross‐reactive protection. Objectives To directly address this using the ferret model, we used two recommended World Health Organization H5N1 vaccine seed strains – A/Vietnam/1203/04 (clade 1) and A/duck/Hunan/795/02 (clade 2.1) – seven single, double, or triple mutant viruses based on A/Vietnam/1203/04, and the ancestral viruses A and D, selected from sequences at nodes of the hemagglutinin and neuraminidase gene phylogenies to represent antigenically diverse progeny H5N1 subclades as vaccine antigens. Results All inactivated whole‐virus vaccines provided full protection against morbidity and mortality in ferrets challenged with the highly pathogenic H5N1 strain A/Vietnam/1203/04 5 months and 1 year after immunization. Conclusion If an H5N1 pandemic was to arise, and with the hypothesis that one can extrapolate the results from three doses of a whole‐virion vaccine in ferrets to the available split vaccines for use in humans, the population could be efficiently immunized with currently available H5N1 vaccines, while the homologous vaccine is under production.     

Seroprevalence of pandemic (H1N1) 2009 influenza and effectiveness of 2010/2011 influenza vaccine during 2010/2011 season in Beijing, China

Please cite this paper as: Yang et al. (2011) Seroprevalence of pandemic (H1N1) 2009 influenza and effectiveness of 2010/2011 influenza vaccine during 2010/2011 season in Beijing, China. Influenza and Other Respiratory Viruses 6(6), 381–388. Background In the post‐pandemic period, pandemic (H1N1) 2009 virus was expected to circulate seasonally and was introduced into trivalent influenza vaccine during 2010/2011 season in the Northern Hemisphere. Objectives The aim of this study was to examine the evolution of herd immunity against pandemic (H1N1) 2009 virus in Beijing, China, during 2010/2011 season and effectiveness of the 2010/2011 trivalent vaccine. Methods Two serological surveys were conducted before and after 2010/2011 season in Beijing. A case–control study was used to investigate vaccine effectiveness against influenza‐like illness (ILI) and lower respiratory tract infection (LRI). Results A total of 4509 and 4543 subjects participated in the pre‐ and post‐season surveys, respectively. The standardized seroprevalence of pandemic (H1N1) 2009 influenza increased from 22·1% pre‐season to 24·3% post‐season (P < 0·001). Significant elevation in seroprevalence appeared in the ≥60 years age‐group (P < 0·001), but not in others. The 2010/2011 trivalent vaccine contributed to the higher post‐seasonal seroprevalence in unvaccinated individuals (P = 0·024), but not in those vaccinated with monovalent pandemic vaccine (P = 0·205), as well as in those without prior immunity versus those with immunity. The adjusted effectiveness of the 2010/2011 trivalent vaccine was 79% protection against ILI (95% CI, 61–89%) and 95% against LRI (95% CI: 59–99%). Conclusions A slight increase in herd immunity against pandemic (H1N1) 2009 influenza was observed in Beijing, China, during the 2010/2011 season. Prior vaccination and immunity had a suppressive impact on immune response toward this novel influenza virus, elicited by 2010/2011 trivalent vaccine. This trivalent vaccine conferred good protection against ILI and LRI.     

Development of a new candidate H5N1 avian influenza virus for pre‐pandemic vaccine production

Background Highly pathogenic H5N1 avian influenza viruses currently circulating in birds have caused hundreds of human infections, and pose a significant pandemic threat. Vaccines are a major component of the public health preparedness for this likely event. The rapid evolution of H5N1 viruses has resulted in the emergence of multiple clades with distinct antigenic characteristics that require clade‐specific vaccines. A variant H5N1 virus termed clade 2.3.4 emerged in 2005 and has caused multiple fatal infections. Vaccine candidates that match the antigenic properties of variant viruses are necessary because inactivated influenza vaccines elicit strain‐specific protection. Objective To address the need for a suitable seed for manufacturing a clade 2.3.4 vaccine, we developed a new H5N1 pre‐pandemic candidate vaccine by reverse genetics and evaluated its safety and replication in vitro and in vivo. Methods A reassortant virus termed, Anhui/PR8, was produced by reverse genetics in compliance with WHO pandemic vaccine development guidelines and contains six genes from A/Puerto Rico/8/34 as well as the neuraminidase and hemagglutinin (HA) genomic segments from the A/Anhui/01/2005 virus. The multi‐basic cleavage site of HA was removed to reduce virulence. Results The reassortant Anhui/PR8 grows well in eggs and is avirulent to chicken and ferrets but retains the antigenicity of the parental A/Anhui/01/2005 virus. Conclusion These results indicate that the Anhui/PR8 reassortant lost a major virulent determinant and it is suitable for its use in vaccine manufacturing and as a reference vaccine virus against the H5N1 clade 2.3.4 viruses circulating in eastern China, Vietnam, Thailand, and Laos.     

A novel electrochemical device to differentiate pandemic (H1N1) 2009 from seasonal influenza

Please cite this paper as: Straight et al. (2010) A novel electrochemical device to differentiate pandemic (H1N1) 2009 from seasonal influenza. Influenza and Other Respiratory Viruses 4(2), 73–79. Background One of the challenges of the recent pandemic (H1N1) 2009 influenza outbreak was to differentiate the virus from seasonal influenza when confronting clinical cases. The determination of the virus has implications on treatment choice, and obvious epidemiologic significance. Objectives We set out to apply a novel electrochemical device to samples derived from clinical cases of pandemic (H1N1) 2009 influenza to examine the ability of the device to differentiate these samples from cases of seasonal influenza. Patients/Methods An IRB approved protocol allowed for the use of original nasal wash samples from 24 confirmed human cases pandemic (H1N1) 2009 influenza. Clinical samples from cases of seasonal influenza (Influenza A/H1N1, A/H3N2, and B) were included as controls. Nucleic acids were extracted and samples examined by the ElectraSense^® Influenza A assay (CombiMatrix, Inc). Samples were also examined by RT-PCR or Luminex assays as a comparator. Results and Conclusions The ElectraSense^® Influenza A assay correctly identified 23 of 24 samples of laboratory-confirmed pandemic (H1N1) 2009 Influenza. The assay correctly identified all samples of influenza A/H1N1 and A/H3N2, and differentiated these from pandemic (H1N1) 2009 Influenza in all cases. The ElectraSense^® Influenza A assay proved to be a useful assay to quickly and accurately differentiate pandemic (H1N1) 2009 influenza from seasonal influenza.     

Pandemic and seasonal influenza viruses among patients with acute respiratory illness in Kashmir (India)

Please cite this paper as: Koul PA., et al. (2011) Pandemic and seasonal influenza viruses among patients with acute respiratory illness in Kashmir (India). Influenza and Other Respiratory Viruses 5(6), e521–e527. Background With the emergence of pandemic influenza A (2009A/H1N1) virus in India, we sought to determine the prevalence and clinical presentations of seasonal and pandemic influenza viruses among acute respiratory illness (ARI) patients from Srinagar, a temperate climate area in northern India, during the peak winter season. Methods Combined throat and nasal swabs, obtained from 194 (108 male) presenting with ARI from January to March 2010 (Week 53‐week 10), were tested by RT‐PCR for influenza A and B, including 2009A/H1N1 viruses. HA1 gene of selected 2009A/H1N1‐positive samples was sequenced, and phylogenetic analysis was carried out. Results Twenty‐one (10·8%, age 15–80 years, median age 40 years) patients tested positive for influenza viruses: 13 (62%) for 2009A/H1N1 virus, 6 (28·5%) for seasonal influenza A (H3N2), and 2 (9·5%) for influenza B. Twelve of the 13 patients with 2009A/H1N1 presented with febrile ARI, and eight had associated comorbidities. All of the patients recovered. Phylogenetic analysis of HA gene (n = 8) revealed that all strains from Srinagar clustered in 2009A/H1N1 clade seven along with the other 2009A/H1N1 strains from India. Amino acid substitutions in the HA protein defining clade seven (P83S, S203T, and I321V) were found in almost all isolates from Srinagar. Conclusions Both seasonal and 2009A/H1N1 viruses appear to be associated with ARI in Srinagar. The 2009A/H1N1 in Srinagar is genetically similar to globally circulating clade 7 strains, with unique signature sequences in the HA gene. Further investigations into ascertain the role of these mutations in possible alteration of the virulence and transmissibility of the virus are needed.     

Absence of cross-reactive antibodies to influenza A (H1N1) 2009 before and after vaccination with 2009 Southern Hemisphere seasonal trivalent influenza vaccine in children aged 6 months-9 years: a prospective study

Please cite this paper as: McVernon et al. (2010) Absence of cross‐reactive antibodies to influenza A (H1N1) 2009 before and after vaccination with 2009 Southern Hemisphere seasonal trivalent influenza vaccine in children aged 6 months–9 years: a prospective study. Influenza and Other Respiratory Viruses 5(1), 7–11. Background Early outbreaks of the pandemic influenza A (H1N1) 2009 virus predominantly involved young children, who fuelled transmission through spread in homes and schools. Seroprevalence studies conducted on stored serum collections indicated low levels of antibody to the novel strain in this age group, leading many to recommend priority immunisation of paediatric populations. Objectives In a prospective study, we sought evidence of cross‐reactive antibodies to the pandemic virus in children who were naïve to seasonal influenza vaccines, at baseline and following two doses of the 2009 Southern Hemisphere trivalent influenza vaccine (TIV). Patients/Methods Twenty children were recruited, with a median age of 4 years (interquartile range 3–5 years); all received two age appropriate doses of TIV. Paired sera were collected pre‐ and post‐vaccination for the assessment of vaccine immunogenicity, using haemagglutination inhibition and microneutralisation assays against vaccine‐related viruses and influenza A (H1N1) 2009. Results Robust responses to H3N2 were observed regardless of age or pre‐vaccination titre, with 100% seroconversion. Fewer seroconverted to the seasonal H1N1 component. Only two children were weakly seropositive (HI titre 40) to the pandemic H1N1 strain at study entry, and none showed evidence of seroconversion by HI assay following TIV administration. Conclusions Administration of 2009 Southern Hemisphere TIV did little to elicit cross‐reactive antibodies to the pandemic H1N1 virus in children, in keeping with assay results on stored sera from studies of previous seasonal vaccines. Our findings support the recommendations for influenza A (H1N1) 2009 vaccination of children in preparation for the 2010 winter season.     

Development of an enzyme‐linked immunoassay for the quantitation of influenza haemagglutinin: an alternative method to single radial immunodiffusion

Please cite this paper as: Bodle et al. (2013) Development of an enzyme‐linked immunoassay for the quantitation of influenza haemagglutinin: an alternative method to single radial immunodiffusion. Influenza and Other Respiratory Viruses 7(2) 191–200. Background The current method used to measure haemagglutinin (HA) content for influenza vaccine formulation, single radial immunodiffusion (SRID), is lengthy and relies on the availability of matched standardised homologous reagents. The 2009 influenza pandemic highlighted the need to develop alternate assays that are able to rapidly quantitate HA antigen for vaccine formulation. Objectives The aim of this work was to develop an enzyme‐linked immunoassay (EIA) for the rapid quantitation of H1, H3, H5 and B influenza HA antigens. Methods Monoclonal antibodies (mAbs) selected for haemagglutination inhibition (HAI) activity were conjugated with horseradish peroxidase and used to establish a capture–detection EIA for the quantitation of HA antigen. Results were compared with the appropriate reference SRID assays to investigate assay performance and utility. Results Quantitation of HA antigen by EIA correlated well with current reference SRID assays. EIA results showed equivalent precision and exhibited a similar capacity to detect HA antigen in virus samples that had been used in either stability or splitting studies, or subjected to physical or chemical stresses. EIA exhibited greater sensitivity than SRID and has the potential to be used in high‐throughput applications. Conclusions We demonstrated the utility of EIA as a suitable alternative to SRID for HA antigen quantitation and stability assessment. This approach would lead to earlier availability of both seasonal and pandemic vaccines, because of the extended cross‐reactivity of reagents.     

Virological characterization of influenza H1N1pdm09 in Vietnam, 2010‐2013

Objectives

Influenza A/H1N1pdm09 virus was first detected in Vietnam on May 31, 2009, and continues to circulate in Vietnam as a seasonal influenza virus. This study has monitored genotypic and phenotypic changes in this group of viruses during 2010–2013 period.

Design and setting

We sequenced hemagglutinin (HA) and neuraminidase (NA) genes from representative influenza A/H1N1pdm09 and compared with vaccine strain A/California/07/09 and other contemporary isolates from neighboring countries. Hemagglutination inhibition (HI) and neuraminidase inhibition (NAI) assays also were performed on these isolates.

Sample

Representative influenza A/H1N1pdm09 isolates (n = 61) from ILI and SARI surveillances in northern Vietnam between 2010 and 2013.

Main outcome measures and results

The HA and NA phylogenies revealed six and seven groups, respectively. Five isolates (8·2%) had substitutions G155E and N156K in the HA, which were associated with reduced HI titers by antiserum raised against the vaccine virus A/California/07/2009. One isolate from 2011 and one isolate from 2013 had a predicted H275Y substitution in the neuraminidase molecule, which was associated with reduced susceptibility to oseltamivir in a NAI assay. We also identified a D222N change in the HA of a virus isolated from a fatal case in 2013.

Conclusions

Significant genotypic and phenotypic changes in A/ H1N1pdm09 influenza viruses were detected by the National Influenza Surveillance System (NISS) in Vietnam between 2010 and 2013 highlighting the value of this system to Vietnam and to the region. Sustained NISS and continued virological monitoring of seasonal influenza viruses are required for vaccine policy development in Vietnam. 3     

Matrix-M adjuvanted virosomal H5N1 vaccine confers protection against lethal viral challenge in a murine model

Please cite this paper as: Pedersen et al. (2011) Matrix‐M adjuvanted virosomal H5N1 vaccine confers protection against lethal viral challenge in a murine model. Influenza and Other Respiratory Viruses 5(6), 426–437. Background A candidate pandemic influenza H5N1 vaccine should provide rapid and long‐lasting immunity against antigenically drifted viruses. As H5N1 viruses are poorly immunogenic, this may require a combination of immune potentiating strategies. An attractive approach is combining the intrinsic immunogenicity of virosomes with another promising adjuvant to further boost the immune response. As regulatory authorities have not yet approved a surrogate correlate of protection for H5N1 vaccines, it is important to test the protective efficacy of candidate H5N1 vaccines in a viral challenge study. Objectives This study investigated in a murine model the protective efficacy of Matrix‐M adjuvanted virosomal influenza H5N1 vaccine against highly pathogenic lethal viral challenge. Methods Mice were vaccinated intranasally (IN) or intramuscularly (IM) with 7·5 μg and 30 μg HA of inactivated A/Vietnam/1194/2004 (H5N1) (NIBRG‐14) virosomal adjuvanted vaccine formulated with or without 10 μg of Matrix‐M adjuvant and challenged IN with the highly pathogenic A/Vietnam/1194/2004 (H5N1) virus. Results and conclusions IM vaccination provided protection irrespective of dose and the presence of Matrix‐M adjuvant, whilst the IN vaccine required adjuvant to protect against the challenge. The Matrix‐M adjuvanted vaccine induced a strong and cross‐reactive serum antibody response indicative of seroprotection after both IM and IN administration. In addition, the IM vaccine induced the highest frequencies of influenza specific CD4+ and CD8+ T‐cells. The results confirm a high potential of Matrix‐M adjuvanted virosomal vaccines and support the progress of this vaccine into a phase 1 clinical trial.     

Obese mice have increased morbidity and mortality compared to non-obese mice during infection with the 2009 pandemic H1N1 influenza virus

Please cite this paper as: Easterbrook et al. (2011) Obese mice have increased morbidity and mortality compared to non‐obese mice during infection with the 2009 pandemic H1N1 influenza virus. Influenza and Other Respiratory Viruses 5(6), 418–425. Background Obesity has been identified as an independent risk factor for severe or fatal infection with 2009 pandemic H1N1 influenza (2009 pH1N1), but was not previously recognized for previous pandemic or seasonal influenza infections. Objectives Our aim was to evaluate the role of obesity as an independent risk factor for severity of infection with 2009 pH1N1, seasonal H1N1, or a pathogenic H1N1 influenza virus. Methods Diet‐induced obese (DIO) and their non‐obese, age‐matched control counterparts were inoculated with a 2009 pH1N1, A/California/04/2009 (CA/09), current seasonal H1N1, A/NY/312/2001 (NY312), or highly pathogenic 1918‐like H1N1, A/Iowa/Swine/1931 (Sw31), virus. Results Following inoculation with CA/09, DIO mice had higher mortality (80%) than control mice (0%) and lost more weight during infection. No effect of obesity on morbidity and mortality was observed during NY312 or Sw31 infection. Influenza antigen distribution in the alveolar regions of the lungs was more pronounced in DIO than control mice during CA/09 infection at 3 days post‐inoculation (dpi), despite similar virus titers. During CA/09 infection, localized interferon‐β and proinflammatory cytokine protein responses in the lungs were significantly lower in DIO than control mice. Conversely, serum cytokine concentrations were elevated in DIO, but not control mice following infection with CA/09. The effect of obesity on differential immune responses was abrogated during NY312 or Sw31 infection. Conclusions Together, these data support epidemiologic reports that obesity may be a risk factor for severe 2009 pandemic H1N1 influenza infection, but the role of obesity in seasonal or highly virulent pandemic influenza infection remains unclear.     

An open‐label phase I trial of a live attenuated H2N2 influenza virus vaccine in healthy adults

Please cite this paper as: Talaat et al. (2012) An open‐label phase I trial of a live attenuated H2N2 influenza virus vaccine in healthy adults. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2012.00350.x. Background Live attenuated influenza vaccines (LAIV) against a variety of strains of pandemic potential are being developed and tested. We describe the results of an open‐label phase I trial of a live attenuated H2N2 virus vaccine. Objectives To evaluate the safety, infectivity, and immunogenicity of a live attenuated H2N2 influenza virus vaccine. Participants/methods The A/Ann Arbor/6/60 (H2N2) virus used in this study is the attenuated, cold‐adapted, temperature‐sensitive strain that provides the genetic backbone of seasonal LAIV (MedImmune). We evaluated the safety, infectivity, and immunogenicity of two doses of 10⁷ TCID₅₀ of this vaccine administered by nasal spray 4 weeks apart to normal healthy seronegative adults. Results Twenty‐one participants received a first dose of the vaccine; 18 participants received a second dose. No serious adverse events occurred during the trial. The most common adverse events after vaccination were headache and musculoskeletal pain. The vaccine was restricted in replication: 24% and 17% had virus detectable by culture or rRT‐PCR after the first and second dose, respectively. Antibody responses to the vaccine were also restricted: 24% of participants developed an antibody response as measured by either hemagglutination‐inhibition assay (10%), or ELISA for H2 HA‐specific serum IgG (24%) or IgA (16%) after either one or two doses. None of the participants had a neutralizing antibody response. Vaccine‐specific IgG‐secreting cells as measured by enzyme‐linked immunospot increased from a mean of 0·5 to 2·0/10⁶ peripheral blood mononuclear cells (PBMCs); vaccine‐specific IgA‐secreting cells increased from 0·1 to 0·5/10⁶ PBMCs. Conclusions The live attenuated H2N2 1960 AA ca vaccine demonstrated a safety profile consistent with seasonal trivalent LAIV but was restricted in replication and minimally immunogenic in healthy seronegative adults.