RESUMO
Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis. Polymorphism in bovine leukocyte antigen (BoLA)-DRB3 allele can influence the host immune response to pathogens, including BLV. However, association between specific BoLA-DRB3 alleles and BLV proviral load (PVL), which is a useful index for estimating disease progression and transmission risk, in Vietnamese cattle are unknown. Here, association study of BoLA-DRB3 allele frequency between cattle with high or low PVL demonstrated BoLA-DRB3*12:01 associates with high PVL in Vietnamese Holstein Friesian (HF) crossbred cattle. This is the first study to demonstrate that BoLA-DRB3 polymorphism confers susceptibility to BLV high PVL in HF crossbred kept in Vietnam. Our results may be useful in disease control and eradiation for BLV through genetic selection.
Assuntos
Bovinos , Vírus da Leucemia Bovina , Alelos , Animais , Bovinos/genética , Antígenos de Histocompatibilidade Classe II/genética , Vírus da Leucemia Bovina/genética , Provírus/genética , Vietnã , Carga Viral/veterináriaRESUMO
We analyzed 2 clusters of 12 patients in Vietnam with severe acute respiratory syndrome coronavirus 2 infection during January-February 2020. Analysis indicated virus transmission from a traveler from China. One asymptomatic patient demonstrated virus shedding, indicating potential virus transmission in the absence of clinical signs and symptoms.
Assuntos
Doenças Assintomáticas , Betacoronavirus , Infecções por Coronavirus/transmissão , Pneumonia Viral/transmissão , Eliminação de Partículas Virais , Adolescente , Adulto , Idoso , COVID-19 , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Pandemias , SARS-CoV-2 , Viagem , Vietnã , Adulto JovemRESUMO
INTRODUCTION: There are two methods of reverse transcription polymerase chain reaction (RT-PCR) that have been the common methods to detect influenza infections: conventional and real-time RT-PCR. From December 2017 to March 2018, several missed diagnoses of influenza A(H1)pdm09 using real-time RT-PCR were reported in northern Viet Nam. This study investigated how these missed detections occurred to determine their effect on the surveillance of influenza. METHODS: The haemagglutinin (HA) segments of A(H1N1)pdm09 from both real-time RT-PCR positive and negative samples were isolated and sequenced. The primer and probe sets in the HA gene were checked for mismatches, and phylogenetic analyses were performed to determine the molecular epidemiology of these viruses. RESULTS: There were 86 positive influenza A samples; 32 were A(H1)pdm09 positive by conventional RT-PCR but were negative by real-time RT-PCR. Sequencing was conducted on 23 influenza (H1N1)pdm09 isolates that were recovered from positive samples. Eight of these were negative for A(H1)pdm09 by real-time RT-PCR. There were two different mismatches in the probe target sites of the HA gene sequences of all isolates (n = 23) with additional mismatches only at position 7 (template binding site) identified for all eight negative real-time RT-PCR isolates. The prime target sites had no mismatches. Phylogenetic analysis of the HA gene showed that both the positive and negative real-time RT-PCR isolates were grouped in clade 6B.1; however, the real-time RT-PCR negative viruses were located in a subgroup that referred to substitution I295V. CONCLUSION: Constant monitoring of genetic changes in the circulating influenza A(H1N1)pdm09 viruses is important for maintaining the sensitivity of molecular detection assays.
Assuntos
Diagnóstico Tardio/tendências , Influenza Humana/diagnóstico , Análise de Sequência de DNA/normas , Testes de Hemaglutinação/métodos , Hemaglutininas/análise , Hemaglutininas/genética , Humanos , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H1N1/patogenicidade , Influenza Humana/epidemiologia , Influenza Humana/mortalidade , Mutação/genética , Filogenia , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Análise de Sequência de DNA/métodos , Análise de Sequência de DNA/tendências , VietnãRESUMO
INTRODUCTION: Influenza B viruses circulate throughout Viet Nam, and their activities vary by region. There have been two antigenically distinct lineages of influenza B viruses co-circulating in the past 20 years; however, only one lineage is selected as a component of contemporary trivalent seasonal influenza vaccines. To improve the understanding of circulating influenza B lineages and influenza vaccine mismatches, we report the virus lineages circulating in northern Viet Nam over an eight-year period (2007-2014). METHODS: Lineages of 331 influenza B viruses were characterized by haemagglutination inhibition assay against standard reference ferret (Yamagata) and sheep (Victoria) antisera. Sequence analysis of the haemagglutinin gene was performed in 64 selected influenza B isolates. RESULTS: The proportion of influenza B lineages changed by year. The Yamagata lineage predominated in 2007, 2008 and 2012; the Victoria lineage predominated in 2009-2014 except 2012. The two lineages showed continuous evolution over time. The Northern Hemisphere's influenza vaccine components were mismatched with the predominant circulating viruses in 2007, 2009 and 2014. DISCUSSION: The seasonality of influenza B activity is more variable in tropical and subtropical regions than in temperate zones. Our data showed a common co-circulation of both influenza B lineages in northern Viet Nam, and it was difficult to predict which one was the predominant lineage. Quadrivalent influenza vaccines containing both lineages may improve the effectiveness of influenza vaccine programmes in the future.
