H1N1 Influenza Strain Research Articles

Clinical and physiological features of postinfectious chronic cough associated with H1N1 infection

Post infectious chronic cough is a disabling illness. In 2009 an influenza pandemic occurred due to a novel strain of H1N1 influenza. Prolonged symptoms such as chronic cough remaining after the infection has cleared have not been examined. This study sought to investigate the prevalence, characteristics and mechanism of chronic cough following laboratory-confirmed H1N1 2009 influenza. Out of 836 eligible patients who had been tested by PCR assay for H1N1, 136 responders participated. Nineteen underwent detailed clinical investigation of cough, and airway function using symptom questionnaires, hypertonic saline challenge, and cough monitoring. Post H1N1 chronic cough was reported by 43%, and chronic cough after non-H1N1 infection was present in 36% of participants. In the participants who progressed to testing objectively measured cough frequency was 3 times greater; there was a 9-fold increase in cough reflex sensitivity and greater quality of life impairment in the participants with postinfectious chronic cough following H1N1 infection than for the participants with no cough following H1N1 infection and for the healthy controls. This study reports the first evaluation of chronic cough following H1N1 infection. Patients that develop chronic cough after H1N1 infection display increased cough reflex sensitivity up to 220 days after confirmed infection. There is an absence of associated risk factors and less impairment in quality of life compared to those patients normally seen in a specialist cough clinic. The associated mechanism was found to be cough reflex hypersensitivity. This clinical trial has been registered with the Australian New Zealand Clinical Trials Register, ACTRN12610000540011.

A contributing role for anti-neuraminidase antibodies on immunity to pandemic H1N1 2009 influenza A virus.

BackgroundExposure to contemporary seasonal influenza A viruses affords partial immunity to pandemic H1N1 2009 influenza A virus (pH1N1) infection. The impact of antibodies to the neuraminidase (NA) of seasonal influenza A viruses to cross-immunity against pH1N1 infection is unknown.Methods and ResultsAntibodies to the NA of different seasonal H1N1 influenza strains were tested for cross-reactivity against A/California/04/09 (pH1N1). A panel of reverse genetic (rg) recombinant viruses was generated containing 7 genes of the H1N1 influenza strain A/Puerto Rico/08/34 (PR8) and the NA gene of either the pandemic H1N1 2009 strain (pH1N1) or one of the following contemporary seasonal H1N1 strains: A/Solomon/03/06 (rg Solomon) or A/Brisbane/59/07 (rg Brisbane). Convalescent sera collected from mice infected with recombinant viruses were measured for cross-reactive antibodies to pH1N1 via Hemagglutinin Inhibition (HI) or Enzyme-Linked Immunosorbent Assay (ELISA). The ectodomain of a recombinant NA protein from the pH1N1 strain (pNA-ecto) was expressed, purified and used in ELISA to measure cross-reactive antibodies. Analysis of sera from elderly humans immunized with trivalent split-inactivated influenza (TIV) seasonal vaccines prior to 2009 revealed considerable cross-reactivity to pNA-ecto. High titers of cross-reactive antibodies were detected in mice inoculated with either rg Solomon or rg Brisbane. Convalescent sera from mice inoculated with recombinant viruses were used to immunize naïve recipient Balb/c mice by passive transfer prior to challenge with pH1N1. Mice receiving rg California sera were better protected than animals receiving rg Solomon or rg Brisbane sera.ConclusionsThe NA of contemporary seasonal H1N1 influenza strains induces a cross-reactive antibody response to pH1N1 that correlates with reduced lethality from pH1N1 challenge, albeit less efficiently than anti-pH1N1 NA antibodies. These findings demonstrate that seasonal NA antibodies contribute to but are not sufficient for cross-reactive immunity to pH1N1.

Effect of the β-Propiolactone Treatment on the Adsorption and Fusion of Influenza A/Brisbane/59/2007 and A/New Caledonia/20/1999 Virus H1N1 on a Dimyristoylphosphatidylcholine/Ganglioside GM3 Mixed Phospholipids Monolayer at the Air–Water Interface

The production protocol of many whole cell/virion vaccines involves an inactivation step with β-propiolactone (BPL). Despite the widespread use of BPL, its mechanism of action is poorly understood. Earlier work demonstrated that BPL alkylates nucleotide bases, but its interaction with proteins has not been studied in depth. In the present study we use ellipsometry to analyze the influence of BPL treatment of two H1N1 influenza strains, A/Brisbane/59/2007 and A/New Caledonia/20/1999, which are used for vaccine production on an industrial scale. Analyses were conducted using a mixed lipid monolayer containing ganglioside GM3, which functions as the viral receptor. Our results show that BPL treatment of both strains reduces viral affinity for the mixed monolayer and also diminishes the capacity of viral domains to self-assemble. In another series of experiments, the pH of the subphase was reduced from 7.4 to 5 to provoke the pH-induced conformational change of hemagglutinin, which occurs following endocytosis into the endosome. In the presence of the native virus the pH decrease caused a reduction in domain size, whereas lipid layer thickness and surface pressure were increased. These observations are consistent with a fusion of the viral membrane with the lipid monolayer. Importantly, this fusion was not observed with adsorbed inactivated virus, which indicates that BPL treatment inhibits the first step of virus-membrane fusion. Our data also indicate that BPL chemically modifies hemagglutinin, which mediates the interaction with GM3.

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.

Immortalized chick embryo cell line adapted to serum-free growth conditions and capable of replicating human and reassortant H5N1 influenza strains for vaccine production

The current process of influenza vaccine production can take 6-9 months and is dependent on the availability of embryonated eggs. Additionally, this process selects for receptor-binding variants with reduced antigenicity and requires significant downstream production for purification. We have established an immortalized chick embryo cell line, termed PBS-12SF, which is adapted to growth in serum free conditions, and is capable of replicating human and reassortant H5N1 influenza strains to high titers. In many cases, PBS-12SF cells produced higher growth titers of influenza virus than those of primary chick embryo kidney (CEK) cells, Madin-Darby Canine Kidney (MDCK) cells and African green monkey kidney cells (Vero). Additionally, in PBS-12SF cell cultures, influenza virus is released into the culture fluid without need for exogenous proteases, which can simplify downstream processing for vaccine production.

Comprehensive Analysis of Pathogen-specific Antibody Response in Vivo Based on an Antigen Library Displayed on Surface of Yeast

Host antibody response is a crucial defense against pathogenic infection. Here, we report a novel technique allowing quantitative measurement of polyclonal antibody response in vivo. This involves expression of a combinatorial library of target proteins from a candidate pathogen on the surface of yeast Saccharomyces cerevisiae. After mixing with serum/plasma from infected or immunized subjects, positive yeast clones were isolated via fluorescence-activated cell sorting (FACS). Using this technique, we have studied mouse immunized serum with recombinant hemagglutinin (HA) protein from a human influenza H5N1 strain (A/Anhui/1/2005) and convalescent plasma from an infected human in China. Our technique has identified novel antigenic domains targeted by serum/plasma and allowed calculation of the relative proportion of the antibody response against each domain. We believe such systematic measurement of an antibody response is unprecedented, and applying this method to different pathogens will improve understanding of protective immunity and guide development of vaccines and therapeutics.

Time-series model to predict impact of H1N1 influenza on a children's hospital

The spring of 2009 witnessed the emergence of a novel influenza A(H1N1) virus resulting in the first influenza pandemic since 1968. In autumn of 2010, the 2009 novel H1N1 influenza strain re-emerged. We performed a retrospective time-series analysis of all patients with laboratory-confirmed H1N1 influenza who presented to our institution during 2009. Cases of influenza were assembled into 3-day aggregates and forecasting models of H1N1 influenza incidence were created. Forecasting estimates of H1N1 incidence for the 2010-2011 season were compared to actual values for our institution to assess model performance. Ninety-five percent confidence intervals calculated around our model's forecasts were accurate to ±3·6 cases per 3-day period for our institution. Our results suggest that time-series models may be useful tools in forecasting the incidence of H1N1 influenza, helping institutions to optimize distribution of resources based on the changing burden of illness.

Enhanced humoral and cell-mediated immune responses after immunization with trivalent influenza vaccine adjuvanted with cationic liposomes

The recent pandemic caused by new influenza A (H1N1) has emphasized the need for improved influenza vaccines with enhanced immune responses that ideally include longlived humoral and CMI responses and mediate a broad protection. This study demonstrates that administration of trivalent influenza vaccine (TIV) with the cationic liposome adjuvant system CAF01 enhances the humoral immune response as measured by hemagglutinin inhibition titers and influenza-specific serum antibody titers, and promote a strong Th1 response with augmented levels of IL-1β, IL-2, IL-12, IFN-γ and TNF-α. Furthermore, high levels of IL-17 are detected in agreement with CAF01's ability to promote TH17 responses. Importantly, the Th1/Th17 cytokine profile is still maintained 20 weeks after the last vaccination. The CAF01 adjuvanted influenza vaccine reduces weight loss and temperature decrease and results in complete survival of mice challenged with the drifted H1N1 influenza strain A/PR/8/34. Overall, the results suggest that CAF01 is a potent adjuvant system for future, improved influenza vaccines.

Efficacy of a pandemic (H1N1) 2009 virus vaccine in pigs against the pandemic influenza virus is superior to commercially available swine influenza vaccines

In April 2009 a new influenza A/H1N1 strain, currently named “pandemic (H1N1) influenza 2009″ (H1N1v), started the first official pandemic in humans since 1968. Several incursions of this virus in pig herds have also been reported from all over the world. Vaccination of pigs may be an option to reduce exposure of human contacts with infected pigs, thereby preventing cross-species transfer, but also to protect pigs themselves, should this virus cause damage in the pig population. Three swine influenza vaccines, two of them commercially available and one experimental, were therefore tested and compared for their efficacy against an H1N1v challenge. One of the commercial vaccines is based on an American classical H1N1 influenza strain, the other is based on a European avian H1N1 influenza strain. The experimental vaccine is based on reassortant virus NYMC X179A (containing the hemagglutinin (HA) and neuraminidase (NA) genes of A/California/7/2009 (H1N1v) and the internal genes of A/Puerto Rico/8/34 (H1N1)). Excretion of infectious virus was reduced by 0.5–3log10 by the commercial vaccines, depending on vaccine and sample type. Both vaccines were able to reduce virus replication especially in the lower respiratory tract, with less pathological lesions in vaccinated and subsequently challenged pigs than in unvaccinated controls. In pigs vaccinated with the experimental vaccine, excretion levels of infectious virus in nasal and oropharyngeal swabs, were at or below 1log10TCID50 per swab and lasted for only 1 or 2 days. An inactivated vaccine containing the HA and NA of an H1N1v is ably to protect pigs from an infection with H1N1v, whereas swine influenza vaccines that are currently available are of limited efficaciousness. Whether vaccination of pigs against H1N1v will become opportune remains to be seen and will depend on future evolution of this strain in the pig population. Close monitoring of the pig population, focussing on presence and evolution of influenza strains on a cross-border level would therefore be advisable.

Evolutionary genomics of the pandemic 2009 H1N1 influenza viruses (pH1N 1v)

BackgroundA new strain of human H1N1 influenza A viruses was broken out in the April 2009 and caused worldwide pandemic emergency. The present study is trying to estimate a temporal reassortment history of 2009 H1N1 viruses by phylogenetic analysis based on a total 394 sequences of H1N1viruses isolated from swine, human and avian.ResultsPhylogenetic trees of eight gene segments showed that viruses sampled from human formed a well-supported clade, whereas swine and avian lineages were intermixed together. A new divergence swine sublineage containing gene segments of 2009 H1N1 viruses was characterized, which were closely related with swine viruses collected from USA and South Korea during 2004 to 2007 in six segments (PB2, PB1, PA, HA, NP and NS), and to swine viruses isolated from Thailand during 2004 to 2005 in NA and M. Substitution rates were varied drastically among eight segments and the average substitution rate was generally higher in 2009 H1N1 than in swine and human viruses (F2,23 = 5.972, P < 0.01). Similarly, higher dN/dS substitution ratios were identified in 2009 H1N1 than in swine and human viruses except M2 gene (F2, 25 = 3.779, P < 0.05). The ages of 2009 H1N1 viruses were estimated around 0.1 to 0.5 year, while their common ancestors with closest related swine viruses existed between 9.3 and 17.37 years ago.ConclusionOur results implied that at least four reassortments or transmissions probably occurred before 2009 H1N1 viruses. Initial reassortment arose in 1976 and avian-like Eurasian swine viruses emerged. The second transmission happened in Asia and North America between 1988 and 1992, and mostly influenced six segments (PB2, PB1, PA, HA, NP and NS). The third reassortment occurred between North American swine and avian viruses during 1998 to 2000, which involved PB2 and PA segments. Recent reassortments occurred among avian-to-swine reassortant, Eurasian and classical swine viruses during 2004 to 2005. South Korea, Thailand and USA, were identified as locations where reassortments most likely happened. The co-circulation of multiple swine sublineages and special lifestyle in Asia might have facilitated mixing of diverse influenza viruses, leading to generate a novel virus strain.

Continent-wide association of H5N1 outbreaks in wild and domestic birds in Europe

The highly pathogenic avian influenza strain H5N1 was first detected in Europe in 2005, and has since been documented continent-wide in wild birds and poultry. However, the relative roles of each host group in transmission remain contentious. Using recently developed tools for analysis of ecological niches and geographic distributions of species, we compared ecological niche requirements for H5N1 between paired host groups (poultry versus wild birds, Anseriformes versus Falconiformes, swans versus non-swan Anseriformes). If environmental signals of different host groups are significantly different, the groups are likely to be involved in distinct transmission cycles. In contrast, models for which similarity cannot be rejected imply no unique ecological niches and no potential linkage of transmission cycles. In 24 similarity tests, we found significant similarity (13/24) or no significant differences (9/24). Although 2 of the 24 analyses showed significant differences, neither was unequivocal, so we conclude an overall signal of niche similarity among groups. We thus could not document distinct ecological niches for H5N1 occurrences in different host groups and conclude that the transmission cycles are broadly interwoven.

Llama-Derived Single Domain Antibodies to Build Multivalent, Superpotent and Broadened Neutralizing Anti-Viral Molecules

For efficient prevention of viral infections and cross protection, simultaneous targeting of multiple viral epitopes is a powerful strategy. Llama heavy chain antibody fragments (VHH) against the trimeric envelope proteins of Respiratory Syncytial Virus (Fusion protein), Rabies virus (Glycoprotein) and H5N1 Influenza (Hemagglutinin 5) were selected from llama derived immune libraries by phage display. Neutralizing VHH recognizing different epitopes in the receptor binding sites on the spikes with affinities in the low nanomolar range were identified for all the three viruses by viral neutralization assays. By fusion of VHH with variable linker lengths, multimeric constructs were made that improved neutralization potencies up to 4,000-fold for RSV, 1,500-fold for Rabies virus and 75-fold for Influenza H5N1. The potencies of the VHH constructs were similar or better than best performing monoclonal antibodies. The cross protection capacity against different viral strains was also improved for all three viruses, both by multivalent (two or three identical VHH) and biparatopic (two different VHH) constructs. By combining a VHH neutralizing RSV subtype A, but not subtype B with a poorly neutralizing VHH with high affinity for subtype B, a biparatopic construct was made with low nanomolar neutralizing potency against both subtypes. Trivalent anti-H5N1 VHH neutralized both Influenza H5N1 clade1 and 2 in a pseudotype assay and was very potent in neutralizing the NIBRG-14 Influenza H5N1 strain with IC50 of 9 picomolar. Bivalent and biparatopic constructs against Rabies virus cross neutralized both 10 different Genotype 1 strains and Genotype 5.The results show that multimerization of VHH fragments targeting multiple epitopes on a viral trimeric spike protein is a powerful tool for anti-viral therapy to achieve “best-in-class” and broader neutralization capacity.

Isolation and complete genomic characterization of H1N1 subtype swine influenza viruses in southern China through the 2009 pandemic

BackgroundThe swine influenza (SI) is an infectious disease of swine and human. The novel swine-origin influenza A (H1N1) that emerged from April 2009 in Mexico spread rapidly and caused a human pandemic globally. To determine whether the tremendous virus had existed in or transmitted to pigs in southern China, eight H1N1 influenza strains were identified from pigs of Guangdong province during 2008-2009.ResultsBased on the homology and phylogenetic analyses of the nucleotide sequences of each gene segments, the isolates were confirmed to belong to the classical SI group, with HA, NP and NS most similar to 2009 human-like H1N1 influenza virus lineages. All of the eight strains were low pathogenic influenza viruses, had the same host range, and not sensitive to class of antiviral drugs.ConclusionsThis study provides the evidence that there is no 2009 H1N1-like virus emerged in southern China, but the importance of swine influenza virus surveillance in China should be given a high priority.

Monoclonal antibodies to the haemagglutinin HA1 subunit of the pandemic influenza A/H1N1 2009 virus and potential application to serodiagnosis

In order to provide specific serological reagents for pandemic influenza A/H1N1 2009 virus, monoclonal antibodies (Mabs) to recombinant haemagglutinin component HA1 (rHA1) were generated after fusing spleen cells from a mouse immunized with rHA1 protein derived from influenza strain A/California/06/09 H1N1 with a mouse myeloma cell line. Five hybridoma clones secreting Mabs specific for the rHA1 protein derived from pandemic influenza A/H1N1 2009 and not for rHA1 from seasonal H1N1 influenza strains A/Brisbane/59/07 and A/Solomon Islands/03/06 were identified by EIA. Mabs 7H4, 9A4, and 9E12 were reactive in Western blots with full length rHA and/or rHA1 subunit derived from A/California/06/09 strain. Only Mab 1F5 inhibited haemagglutination of turkey red blood cells with recombinant NIBRG-121 virus derived from A/California/07/09, but did not react in Western blots. Immunostaining of MDCK cells infected with NIBRG-121 was localized to the membrane/cytoplasm for four of the reactive Mabs. The differing reactivity of the Mabs in Western blots, immunostaining, EIA, and haemagglutination inhibition assay suggest that at least four of the five Mabs recognize different epitopes on HA1 of the pandemic influenza A/H1N1 2009 virus. Ferret antisera to pandemic influenza A/H1N1 2009 (A/England/195/09 and A/California/07/09 strains) and sera from human subjects vaccinated with Influenza A (H1N1) 2009 Monovalent Vaccine (CELTURA®, Novartis Vaccines, Germany), inhibit binding of 1F5-HRP to biotinylated rHA1 derived from A/California/06/09 in a competitive EIA, suggesting that the epitope recognized by this Mab also evokes an antibody response in infected ferrets and vaccinated humans.

Broadly cross-reactive antibodies dominate the human B cell response against 2009 pandemic H1N1 influenza virus infection

The 2009 pandemic H1N1 influenza pandemic demonstrated the global health threat of reassortant influenza strains. Herein, we report a detailed analysis of plasmablast and monoclonal antibody responses induced by pandemic H1N1 infection in humans. Unlike antibodies elicited by annual influenza vaccinations, most neutralizing antibodies induced by pandemic H1N1 infection were broadly cross-reactive against epitopes in the hemagglutinin (HA) stalk and head domain of multiple influenza strains. The antibodies were from cells that had undergone extensive affinity maturation. Based on these observations, we postulate that the plasmablasts producing these broadly neutralizing antibodies were predominantly derived from activated memory B cells specific for epitopes conserved in several influenza strains. Consequently, most neutralizing antibodies were broadly reactive against divergent H1N1 and H5N1 influenza strains. This suggests that a pan-influenza vaccine may be possible, given the right immunogen. Antibodies generated potently protected and rescued mice from lethal challenge with pandemic H1N1 or antigenically distinct influenza strains, making them excellent therapeutic candidates.

CD8+ T cell immunity to 2009 pandemic and seasonal H1N1 influenza viruses

A novel strain of H1N1 influenza A virus (pH1N1) emerged in 2009, causing a worldwide pandemic. Several studies suggest that this virus is antigenically more closely related to human influenza viruses that circulated prior to 1957 than viruses of more recent seasonal influenza varieties. The extent to which individuals who are naïve to the 2009 pH1N1 virus carry cross-reactive CD8+ T cells is not known, but a certain degree of reactivity would be expected since there is substantial conservation among the internal proteins of the virus. In the present study, we examined the production of multiple cytokines in response to virus from CD8+ T cells in healthy adult subjects, between 18 and 50 years of age (born post 1957), who had no evidence of exposure to the 2009 pH1N1 virus, and had blood collected prior to the emergence of the pandemic in April of 2009. Human peripheral blood mononuclear cells (PBMCs) were stimulated in vitro with a panel of live viruses, and assayed by intracellular cytokine staining and flow cytometry. Although results were variable, most subjects exhibited cytokine positive CD8+ T cells in response to pH1N1. Cytokine producing cells were predominantly single positive (IL2, IFNγ, or TNFα); triple-cytokine producing cells were relatively rare. This result suggests that although many adults carry cross-reactive T cells against the emergent pandemic virus, these cells are in a functionally limited state, possibly because these subjects have not had recent exposure to either seasonal or pandemic influenza strains.

Vaccine protection against lethal homologous and heterologous challenge using recombinant AAV vectors expressing codon-optimized genes from pandemic swine origin influenza virus (SOIV)

The recent H1N1 influenza pandemic and the inevitable delay between identification of the virus and production of the specific vaccine have highlighted the urgent need for new generation influenza vaccines that can preemptively induce broad immunity to different strains of the virus. In this study we have produced AAV-based vectors expressing the A/Mexico/4603/2009 (H1N1) hemagglutinin (HA), nucleocapsid (NP) and the matrix protein M1 and have evaluated their ability to induce specific immune response and protect mice against homologous and heterologous challenge. Each of the vaccine vectors elicited potent cellular and humoral immune responses in mice. Although immunization with AAV-M1 did not improve survival after challenge with the homologous strain, immunization with the AAV-H1 and AAV-NP vectors resulted in survival of all mice, as did inoculation with a combination of all three vectors. Furthermore, trivalent vaccination also conferred partial protection against challenge with the highly heterologous and virulent A/PR/8/34 strain of H1N1 influenza.

Iota-Carrageenan Is a Potent Inhibitor of Influenza A Virus Infection

The 2009 flu pandemic and the appearance of oseltamivir-resistant H1N1 influenza strains highlight the need for treatment alternatives. One such option is the creation of a protective physical barrier in the nasal cavity. In vitro tests demonstrated that iota-carrageenan is a potent inhibitor of influenza A virus infection, most importantly also of pandemic H1N1/2009 in vitro. Consequently, we tested a commercially available nasal spray containing iota-carrageenan in an influenza A mouse infection model. Treatment of mice infected with a lethal dose of influenza A PR8/34 H1N1 virus with iota-carrageenan starting up to 48 hours post infection resulted in a strong protection of mice similar to mice treated with oseltamivir. Since alternative treatment options for influenza are rare, we conclude that the nasal spray containing iota-carrageenan is an alternative to neuraminidase inhibitors and should be tested for prevention and treatment of influenza A in clinical trials in humans.

898 Pandemic Influenza (H1N1) Infection in Pediatric Age Group in Southern Iran

Background: A novel strain of H1N1 Influenza (A/ California/7/2009) has been prevalent since April 2009. Epidemiological and clinical studies showed that children at high risk for severe infection. Objective: to determined the prevalence of new H1N1 in children with fever, cough, sore throat, bronchiolitis, pneumonia and wheezing symptoms. Methods: pharyngeal swabs were taken from 450 children aged (1-60 months) with respiratory tract symptom between June 2009 to April 2010. The specimens were tested using real time reverse transcription-PCR. Results: out of 450 samples 130 were tested positive for pandemic H1N1 infection. Conclusion: According to our results 29.1% of respiratory infection in children in the south of Iran was due to new H1N1 during the foregoing pandemic. Our analysis revealed no significant correlation between males and females.

Demographic and attitudinal determinants of protective behaviours during a pandemic: A review

Purpose. A new strain of H1N1 influenza, also known as swine flu was confirmed in the UK in May 2009 and has spread to over 100 countries around the world causing the World Health Organization to declare a global flu pandemic. The primary objectives of this review are to identify the key demographic and attitudinal determinants of three types of protective behaviour during a pandemic: preventive, avoidant, and management of illness behaviours, in order to describe conceptual frameworks in which to better understand these behaviours and to inform future communications and interventions in the current outbreak of swine flu and subsequent influenza pandemics. Methods. Web of Science and PubMed databases were searched for references to papers on severe acute respiratory syndrome, avian influenza/flu, H5N1, swine influenza/flu, H1N1, and pandemics. Forward searching of the identified references was also carried out. In addition, references were gleaned from an expert panel of the Behaviour and Communications sub‐group of the UK Scientific Pandemic Influenza Advisory Group. Papers were included if they reported associations between demographic factors, attitudes, and a behavioural measure (reported, intended, or actual behaviour). Results. Twenty‐six papers were identified that met the study inclusion criteria. The studies were of variable quality and most lacked an explicit theoretical framework. Most were cross‐sectional in design and therefore not predictive over time. The research shows that there are demographic differences in behaviour: being older, female and more educated, or non‐White, is associated with a higher chance of adopting the behaviours. There is evidence that greater levels of perceived susceptibility to and perceived severity of the diseases and greater belief in the effectiveness of recommended behaviours to protect against the disease are important predictors of behaviour. There is also evidence that greater levels of state anxiety and greater trust in authorities are associated with behaviour. Conclusions. The findings from this review can be broadly explained by theories of health behaviour. However, theoretically driven prospective studies are required to further clarify the relationship between demographic factors, attitudes, and behaviour. The findings suggest that intervention studies and communication strategies should focus on particular demographic groups and on raising levels of perceived threat of the pandemic disease and belief in the effectiveness of measures designed to protect against it.