Diverse antigenic site targeting of influenza hemagglutinin in the murine antibody recall response to A(H1N1)pdm09 virus.

Here we define the epitopes on HA that are targeted by a group of 9 recombinant monoclonal antibodies (rmAbs) isolated from memory B cells of mice, immunized by infection with A(H1N1)pdm09 virus followed by a seasonal TIV boost. These rmAbs were all reactive against the HA1 region of HA, but display 7 distinct binding footprints, targeting each of the 4 known antigenic sites. Although the rmAbs were not broadly cross-reactive, a group showed subtype-specific cross-reactivity with the HA of A/South Carolina/1/18. Screening these rmAbs with a panel of human A(H1N1)pdm09 virus isolates indicated that naturally-occurring changes in HA could reduce rmAb binding, HI activity, and/or virus neutralization activity by rmAb, without showing changes in recognition by polyclonal antiserum. In some instances, virus neutralization was lost while both ELISA binding and HI activity were retained, demonstrating a discordance between the two serological assays traditionally used to detect antigenic drift.

Oseltamivir-resistant influenza A(H1N1)pdm09 viruses, United States, 2013-14.

We report characteristics of oseltamivir-resistant influenza A(H1N1)pdm09 viruses and patients infected with these viruses in the United States. During 2013-14, fifty-nine (1.2%) of 4,968 analyzed US influenza A(H1N1)pdm09 viruses had the H275Y oseltamivir resistance-conferring neuraminidase substitution. Our results emphasize the need for local surveillance for neuraminidase inhibitor susceptibility among circulating influenza viruses.

Seasonal influenza vaccine policies, recommendations and use in the World Health Organization's Western Pacific Region.

OBJECTIVE: Vaccination is the most effective way to prevent seasonal influenza and its severe outcomes. The objective of our study was to synthesize information on seasonal influenza vaccination policies, recommendations and practices in place in 2011 for all countries and areas in the Western Pacific Region of the World Health Organization (WHO). METHODS: Data were collected via a questionnaire on seasonal influenza vaccination policies, recommendations and practices in place in 2011. RESULTS: Thirty-six of the 37 countries and areas (97%) responded to the survey. Eighteen (50%) reported having established seasonal influenza vaccination policies, an additional seven (19%) reported having recommendations for risk groups for seasonal influenza vaccination only and 11 (30%) reported having no policies or recommendations in place. Of the 25 countries and areas with policies or recommendations, health-care workers and the elderly were most frequently recommended for vaccination; 24 (96%) countries and areas recommended vaccinating these groups, followed by pregnant women (19 [76%]), people with chronic illness (18 [72%]) and children (15 [60%]). Twenty-six (72%) countries and areas reported having seasonal influenza vaccines available through public funding, private market purchase or both. Most of these countries and areas purchased only enough vaccine to cover 25% or less of their populations. DISCUSSION: In light of the new WHO position paper on influenza vaccines published in 2012 and the increasing availability of country-specific data, countries and areas should consider reviewing or developing their seasonal influenza vaccination policies to reduce morbidity and mortality associated with annual epidemics and as part of ongoing efforts for pandemic preparedness.

Surveillance of influenza in Indonesia, 2003­2007.

BACKGROUND: Longitudinal data are limited about the circulating strains of influenza viruses and their public health impact in Indonesia. We conducted influenza surveillance among outpatients and hospitalized patients with influenza-like illness (ILI) across the Indonesian archipelago from 2003 through 2007. METHODOLOGY: Demographic, clinical data, and respiratory specimens were collected for 4236 ILI patients tested for influenza virus infection by RT-PCR and viral culture. PRINCIPAL FINDINGS: Influenza A and B viruses co-circulated year-round with seasonal peaks in influenza A virus activity during the rainy season (December­January). During 2003­2007, influenza viruses were identified in 20·1% (4236 / 21 030) of ILI patients, including 20·1% (4015 / 20 012) of outpatients, and 21·7% (221 / 1018) of inpatients. One H5N1 case was identified retrospectively in an outpatient with ILI. Antigenic drift in circulating influenza A and B virus strains was detected during the surveillance period in Indonesia. In a few instances, antigenically drifted viruses similar to the World Health Organization (WHO) vaccine strains were detected earlier than the date of their designation by WHO. CONCLUSIONS: Influenza A and B virus infections are an important cause of influenza-like illness among outpatients and hospitalized patients in Indonesia. While year-round circulation of influenza viruses occurs, prevention and control strategies should be focused upon the seasonal peak during rainy season months. Ongoing virologic surveillance and influenza disease burden studies in Indonesia are important priorities to better understand the public health impact of influenza in South-East Asia and the implications of influenza viral evolution and global spread.

Detection and characterization of clade 7 high pathogenicity avian influenza H5N1 viruses in chickens seized at ports of entry and live poultry markets in Vietnam.

High pathogenicity avian influenza H5N1 has become an endemic poultry disease in several Asian countries, including Vietnam. Recently, dade 7 H5N1 viruses of the Eurasian lineage were isolated from chickens seized at ports of entry in Lang Son Province, Vietnam. Extensive nucleotide and amino acid divergence across the hemagglutinin (HA) protein gene of these isolates in comparison to previously described clade 7 viruses was identified. Clade 7 viruses are antigenically distinct from contemporary strains of H5N1 known to circulate in Vietnamese poultry (clade 1 and clade 2.3.4). Subsequent surveillance of sick poultry in live poultry markets in Hai Duong Province identified additional clade 7 isolates with HA genes very similar to the group B virus cluster detected previously at the Lang Son Province border. Antigenic analysis of the isolates from the live bird markets revealed significant cross-reactivity only between those clade 7 viruses belonging to the same subgroups. To meet pandemic response preparedness objectives, we have developed a reassortant virus from A/chicken/Vietnam/NCVD-016/2008, which could be used as a new prepandemic vaccine candidate for veterinary or human vaccination, should the need arise. Findings from these studies indicate that viruses with clade 7 HA have continued to evolve in Southeast Asian poultry, leading to significant antigenic drift relative to other H5N1 viruses currently circulating in Vietnam.

Antigenic and genetic diversity of highly pathogenic avian influenza A (H5N1) viruses isolated in Egypt.

Highly pathogenic avian influenza A virus (H5N1) has diverged antigenically and genetically since its initial detection in Asia in 1997. Viruses belonging to clade 2.2 in particular have been reported in numerous countries with the majority occurring in Egypt. Previous reports identified antigenic similarities between viruses belonging to clade 2.2. However, poultry and human viruses isolated in northern Egypt during 2007 and 2008 were found to be antigenically distinct from other clade 2.2 viruses from this country. Genetic analysis of the hemagglutinin revealed a high degree of nucleotide and amino acid divergence. The antigenic changes in Egyptian viruses isolated during 2007-08 necessitated that two of these strains be considered as potential H5N1 pre-pandemic vaccine candidates.