Assessing Antigenic Drift of Seasonal Influenza A(H3N2) and A(H1N1)pdm09 Viruses.

Under selective pressure from the host immune system, antigenic epitopes of influenza virus hemagglutinin (HA) have continually evolved to escape antibody recognition, termed antigenic drift. We analyzed the genomes of influenza A(H3N2) and A(H1N1)pdm09 virus strains circulating in Thailand between 2010 and 2014 and assessed how well the yearly vaccine strains recommended for the southern hemisphere matched them. We amplified and sequenced the HA gene of 120 A(H3N2) and 81 A(H1N1)pdm09 influenza virus samples obtained from respiratory specimens and calculated the perfect-match vaccine efficacy using the pepitope model, which quantitated the antigenic drift in the dominant epitope of HA.

Influenza activity in Thailand and occurrence in different climates.

This study observed influenza activity between June 2009 and July 2014 in Thailand, a country in the Northern hemisphere with a tropical climate, and compared the results to activity in the United States (US) and Australia, which represent temperate climates in the Northern and Southern hemispheres, respectively. From Thailand, a total of 17,416 specimens were collected from patients exhibiting influenza-like illnesses and subjected to real-time PCR for the detection of influenza viruses. For comparison, laboratory confirmations of influenza originating from the US and Australia were obtained from the US CDC's FluView surveillance reports and the Australian Government's Department of Health and Ageing websites.

Molecular epidemiology and phylogenetic analyses of influenza B virus in Thailand during 2010 to 2014.

Influenza B virus remains a major contributor to the seasonal influenza outbreak and its prevalence has increased worldwide. We investigated the epidemiology and analyzed the full genome sequences of influenza B virus strains in Thailand between 2010 and 2014. Samples from the upper respiratory tract were collected from patients diagnosed with influenza like-illness.

Exploring the potential of next-generation sequencing in detection of respiratory viruses.

Efficient detection of human respiratory viral pathogens is crucial in the management of patients with acute respiratory tract infection. Sequence-independent amplification of nucleic acids combined with next-generation sequencing technology and bioinformatics analyses is a promising strategy for identifying pathogens in clinical and public health settings. It allows the characterization of hundreds of different known pathogens simultaneously and of novel pathogens that elude conventional testing.

Epidemiology of seasonal influenza in Bangkok between 2009 and 2012.

Introduction: This study investigated influenza activity in Bangkok, Thailand between June 2009 and July 2012.

Methodology: Real-time reverse transcription polymerase chain reaction (RT-PCR) was performed to detect influenza viruses among patients with influenza-like illnesses.

Results: Of the 6417 patients tested, influenza virus infection was detected in 42% (n = 2697) of the specimens.

Global alert to avian influenza virus infection: from H5N1 to H7N9.

Outbreak of a novel influenza virus is usually triggered by mutational change due to the process known as 'antigenic shift' or re-assortment process that allows animal-to-human or avian-to-human transmission. Birds are a natural reservoir for the influenza virus, and subtypes H5, H7, and H9 have all caused outbreaks of avian influenza in human populations. An especially notorious strain is the HPAI influenza virus H5N1, which has a mortality rate of approximately 60% and which has resulted in numerous hospitalizations, deaths, and significant economic loss.

Whole genome characterization, phylogenetic and genome signature analysis of human pandemic H1N1 virus in Thailand, 2009-2012.

Background: Three waves of human pandemic influenza occurred in Thailand in 2009-2012. The genome signature features and evolution of pH1N1 need to be characterized to elucidate the aspects responsible for the multiple waves of pandemic.

Methodology/findings: Forty whole genome sequences and 584 partial sequences of pH1N1 circulating in Thailand, divided into 1(st), 2(nd) and 3(rd) wave and post-pandemic were characterized and 77 genome signatures were analyzed.

Evaluation of rapid influenza virus tests in patients with influenza-like illness in Thailand.

Background: The influenza virus is responsible for causing major respiratory tract symptoms. A fast, accurate diagnosis is essential for efficient treatment, especially in patients with complications. The Rapid Influenza Diagnostic Tests (RIDTs) for influenza detection have been developed to subtype the influenza virus.

Influenza surveillance in southern Thailand during 2009-2010.

The aim of this study was to determine the epidemiology of influenza infection among patients with influenza-like illness by real-time RT-PCR in southern Thailand from August 2009 to January 2011. The predominant strain in Thung Song District was influenza A. Sporadic cases of influenza occured year round but the incidence peaked from August to November 2009 and July to November 2010.

Erythrocyte binding preference of human pandemic influenza virus a and its effect on antibody response detection.

Background: Validation of hemagglutination inhibition (HI) assays is important for evaluating antibody responses to influenza virus, and selection of erythrocytes for use in these assays is important. This study aimed to determine the correlation between receptor binding specificity and effectiveness of the HI assay for detecting antibody response to pandemic influenza H1N1 (pH1N1) virus.

Methods: Hemagglutination (HA) tests were performed using erythrocytes from 6 species.

Seroprevalence of antibody against diphtheria among the population in Khon Kaen province, Thailand.

To assess diphtheria immunity in the northeastern region of Thailand, a seroepidemiological survey was undertaken in 2011 from 516 healthy individuals (age range 2-87 years) in Khon Kaen province. Diphtheria antitoxin levels were measured by enzyme-linked immunosorbent assay and titers of ≥0.1 IU/mL were considered to be protective antitoxin levels.

Epidemiological and serological surveillance of human pandemic influenza A virus infections during 2009-2010 in Thailand.

Since April 2009, the outbreak of human pandemic influenza A (H1N1) virus (pH1N1) infection has spread from North America to other parts of the world, and currently, pH1N1 is the predominant circulating strain of influenza viruses. Our objectives were to perform a serological survey of medical personnel at the Chumphae Hospital in Thailand and to investigate the prevalence of pH1N1 in randomly selected patients diagnosed with respiratory tract disease. Prevalence of pH1N1 in the patients was determined by performing real-time reverse transcription-polymerase chain reaction.

Pandemic (H1N1) 2009 virus infection: persistent viral shedding after Oseltamivir treatment.

Objectives: To study pandemic (H1N1) 2009 virological outcomes after Oseltamivir treatment in confirmed cases of pandemic (H1N1) 2009 virus infections. A hospital-based cohort study was conducted in south Thailand, between June and September 2009.

Methods: Throat/swab specimens were tested by real-time reverse transcriptase polymerase chain reaction (rRT-PCR) for pandemic (H1N1) 2009.

Serological analysis of human pandemic influenza (H1N1) in Thailand.

The study was aimed at determining the prevalence of pandemic influenza (H1N1) 2009 among patients with respiratory tract diseases during July-December 2009 using real-time reverse transcription polymerase chain reaction. Haemagglutination inhibition (HI) assay was performed to detect antibody titres against pandemic influenza in 255 medical personnel, 307 members of the general population during the second week of December 2009 in Khon Kaen province, Thailand, and in 100 stored sera collected from people of different age-groups during 2008. The results showed that the pandemic (H1N1) 2009 had occurred during July-December 2009.

Determination of antibody response to the human pandemic influenza H1N1 2009 among patients with influenza-like illness and high risk groups.

The global population has been exposed to the novel pandemic H1N1 influenza virus since mid March 2009, causing the expansion of respiratory illness around the world, including Thailand. To evaluate the antibody titers against human pandemic influenza (H1N1) in Thai people with influenza-like illness (ILI), 45 paired serum samples (acute and convalescent) were subjected to hemagglutination inhibition (HI) test and real-time RT-PCR. Most serum samples of ILI patients positive by real-time RT-PCR displayed an at least four-fold antibody increase of HI titers against pandemic influenza (H1N1).