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Chad M Cox,
Kate Goodin,
Emily Fisher,
Fatimah S Dawood,
Janet J Hamilton,
German F Leparc,
Monica Gray,
Linda Nelson,
Rebekah H Borse,
James A Singleton,
Carrie Reed, Amanda L Balish,
Jacqueline M Katz,
Richard S Hopkins,
Alicia M Fry
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ABSTRACT: In 2009, a novel influenza virus (2009 pandemic influenza A (H1N1) virus (pH1N1)) caused significant disease in the United States. Most states, including Florida, experienced a large fall wave of disease from September through November, after which disease activity decreased substantially. We determined the prevalence of antibodies due to the pH1N1 virus in Florida after influenza activity had peaked and estimated the proportion of the population infected with pH1N1 virus during the pandemic.
During November-December 2009, we collected leftover serum from a blood bank, a pediatric children's hospital and a pediatric outpatient clinic in Tampa Bay Florida. Serum was tested for pH1N1 virus antibodies using the hemagglutination-inhibition (HI) assay. HI titers ≥40 were considered seropositive. We adjusted seroprevalence results to account for previously established HI assay specificity and sensitivity and employed a simple statistical model to estimate the proportion of seropositivity due to pH1N1 virus infection and vaccination.
During the study time period, the overall seroprevalence in Tampa Bay, Florida was 25%, increasing to 30% after adjusting for HI assay sensitivity and specificity. We estimated that 5.9% of the population had vaccine-induced seropositivity while 25% had seropositivity secondary to pH1N1 virus infection. The highest cumulative incidence of pH1N1 virus infection was among children aged 5-17 years (53%) and young adults aged 18-24 years (47%), while adults aged ≥50 years had the lowest cumulative incidence (11-13%) of pH1N1 virus infection.
After the peak of the fall wave of the pandemic, an estimated one quarter of the Tampa Bay population had been infected with the pH1N1 virus. Consistent with epidemiologic trends observed during the pandemic, the highest burdens of disease were among school-aged children and young adults.
PLoS ONE 01/2011; 6(12):e29301. · 4.09 Impact Factor
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Amanda L. Balish,
C. Todd Davis,
Magdi D. Saad,
Nasr El-Sayed,
Hala Esmat,
Jeffrey A. Tjaden,
Kenneth C. Earhart,
Lu'ay E. Ahmed,
Mohamed Abd El-Halem,
Abdel Hakem M. Ali,
Samir A. Nassif,
Elham A. El-Ebiary,
M. Taha,
M. Aly Mona,
Abdelstattar Arafa,
Eduardo O'Neill,
Xu Xiyan,
Nancy J. Cox,
Ruben O. Donis,
Alexander I. Klimov
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ABSTRACT: Diversidad antigénica y genética de aislamientos del virus de Influenza Aviar de alta patogenicidad subtipo H5N1 en Egipto. El subtipo H5N1 de Influenza Aviar de alta patogenicidad ha mostrado diversidad antigénica y genética desde su detección inicial en Asia en el año 1997. En particular, los virus pertenecientes al clado 2.2 han sido reportados en numerosos países, en su mayoría provenientes de casos observados en Egipto. Reportes previos identificaron similitudes antigénicas entre los virus pertenecientes al clado 2.2. Sin embargo, los virus aviares y humanos aislados en el norte de Egipto durante los años 2007 y 2008 fueron antigénicamente distintos de otros virus del clado 2.2 de este país. El análisis genético de la hemaglutinina reveló un alto grado de divergencia de los nucleótidos y aminoácidos. Los cambios antigénicos observados en los virus egipcios aislados durante el 2007 y el 2008 hacen necesario que dos de estas cepas se consideren como candidatas potenciales a ser virus vacunales H5N1 pre-pandémicos. Abbreviations: CDC = Centers for Disease Control and Prevention; CLEVB = Central Laboratory for Veterinary Biologics Evaluation; GS/GD = A/Goose/Guangdong/1/96; HA = hemagglutinin; HI = hemagglutination inhibition; HPAI = highly pathogenic avian influenza; NAMRU-3 = U.S. Naval Medical Research Unit No. 3; NLQP = National Laboratory for Quality Control of Poultry Production; PBS = phosphate buffered saline; RT-PCR = reverse transcription-polymerase chain reaction; WHO = World Health Organization
Avian Diseases 03/2010; · 1.46 Impact Factor
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Amanda L Balish,
C Todd Davis,
Magdi D Saad,
Nasr El-Sayed,
Hala Esmat,
Jeffrey A Tjaden,
Kenneth C Earhart,
Lu'ay E Ahmed,
Mohamed Abd El-Halem,
Abdel Hakem M Ali,
Samir A Nassif,
Elham A El-Ebiary,
M Taha,
Mona M Aly,
Abdelstattar Arafa,
Eduardo O'Neill,
Xu Xiyan,
Nancy J Cox,
Ruben O Donis,
Alexander I Klimov
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ABSTRACT: 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.
Avian Diseases 03/2010; 54(1 Suppl):329-34. · 1.46 Impact Factor
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ABSTRACT: 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.
Avian Diseases 03/2010; 54(1 Suppl):307-12. · 1.46 Impact Factor
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ABSTRACT: Influenza viruses are negative-sense, single-stranded, enveloped RNA viruses belonging to the family Orthomyxoviridae. Three types exist, influenza A, B, and C. All infect humans, but only A and B are major human pathogens. Influenza type A viruses are divided into subtypes based on genetic and antigenic differences in the two surface spike proteins, hemagglutinin (HA) and neuraminidase (NA). The appropriate cell lines to be used for isolation of influenza A or B viruses depend on the clinical information and the host of origin. MDCK cells are the preferred cell line for isolation of human influenza viruses from clinical specimens.
Current protocols in microbiology 01/2007; Chapter 15:Unit 15G.1.
