No abstract available.
Humans ; Influenza A Virus, H1N1 Subtype/*isolation & purification ; Influenza, Human/*diagnosis

No abstract available.
Hepatitis A/*epidemiology ; Humans ; Influenza A Virus, H1N1 Subtype/*isolation & purification ; Influenza, Human/*epidemiology

Global Health ; History, 20th Century ; Humans ; Influenza A Virus, H1N1 Subtype ; genetics ; isolation & purification ; Influenza A Virus, H3N2 Subtype ; genetics ; isolation & purification ; Influenza, Human ; epidemiology ; history ; therapy ; virology ; Russia ; epidemiology

OBJECTIVETo establish and evaluate a single-tube multiplex RT-real time PCR assay for detecting novel influenza A H1N1, influenza A and influenza B viruses (called "IV" for short) simultaneously.

METHODSA total of 213 clinical specimens of influenza-like patient's throat swab were collected during October 2010 and April 2011. 152 bp fragment in HA gene of novel influenza A H1N1 virus, 128 bp fragment in M gene of influenza A virus and 107 bp fragment in NP gene of influenza B virus were chosen as the target genes for multiplex RT-real time PCR, a specific primers and probes labeled with different fluoresceins were designed. The standard plasmid was constructed using in vitro transcription assay, and the standard curve was established. The reproducibility, specificity and sensitivity of the assay were evaluated. Furthermore, RNA extracted from 213 clinical specimens of throat swab was detected and verified by sequencing.

RESULTSThe corresponding standard curves of novel influenza A H1N1 virus, influenza A virus and influenza B virus were Y = - 3.46 lgX + 46.985, Y = - 3.49 lgX + 37.709, Y = - 3.51 lgX + 38.889, respectively; Y was cycle threshold (Ct), and lgX was logarithm value of virus replication number. The standard curve coefficient was 0.998. The detection limit of this assay was 10(2) copies/microl in one reaction. The specificity was strong. 39 (18.3%), 63 (29.6%) and 23 (10.8%) of 213 clinical specimens detected were positive for novel influenza A H1N1 virus RNA,influenza A virus RNA and influenza B virus RNA respectively. The positive samples were verified by sequencing.

CONCLUSIONThe single-tube multiplex RT-real time PCR assay developed in this study for detecting and identifying novel influenza A H1N1, influenza A and influenza B viruses simultaneously was rapid, specific and sensitive.

Humans ; Influenza A Virus, H1N1 Subtype ; genetics ; isolation & purification ; Influenza A virus ; genetics ; isolation & purification ; Influenza B virus ; genetics ; isolation & purification ; Reverse Transcriptase Polymerase Chain Reaction ; methods

OBJECTIVETo establish a multiplex RT-PCR-based reverse dot blot hybridization technique to detect influenza viruses.

METHODSObtain the HA nucleotide sequences of seasonal influenza H1N1, seasonal influenza H3N2, influenza H1N1 and human avian influenza H5N1 from GenBank. Design primers in conservative district and probes t in high variable region respectively, after analyzing the HA nucleotide sequences of influenza virus through the Vector NTI 9.0. Establish and optimize multiple RT-PCR system by comparing amplification efficiency and specificity at different primer concentrations. Establish the reverse dot hybridization system after optimizing the concentration of probes. To compare the sensitivity and specificity of this technique and the general RT-PCR Method through extracting the viral RNA of the mentioned influenza virus which are to be the reference substance.

RESULTSSuccessfully establish a multiplex RT-PCR-based reverse dot blot hybridization technique for detecting influenza viruses. This technique is 100-1000 times more sensitive than gel electrophoresis method, and it has a good specificity.

CONCLUSIONSuccessfully established multiplex RT-PCR-based reverse dot blot hybridization technique for detecting influenza viruses.

Humans ; Influenza A Virus, H1N1 Subtype ; genetics ; isolation & purification ; Influenza A Virus, H3N2 Subtype ; genetics ; isolation & purification ; Influenza A Virus, H5N1 Subtype ; genetics ; isolation & purification ; Influenza, Human ; diagnosis ; virology ; Nucleic Acid Hybridization ; methods ; Reverse Transcriptase Polymerase Chain Reaction ; methods ; Sensitivity and Specificity

OBJECTIVETo analyse seasonal influenza epidemic situation in 2006, and to analyse the genetic and antigenic characteristics of viral hemagglutinin (HA) gene.

METHODSThe single-way hemagglutination inhibition (HI) tests were used to test the antigenic characteristics of these viruses from influenza surveillance network, and the HA1 genes were sequenced based on the antigenic test results according to different isolation times and sites.

RESULTSThe influenza virus types A and B co-circulated in 2006. influenza A H1N1 subtype and Victoria-like B influenza circulated preponderantly during this epidemic season. The HA1 gene sequence of H1N1 viruses showed that 192, 193, 196, 198 positions (located at antigenic site B) have an amino acid substitute, compared with the last circulating strain A/Hubeihongshan/53/2005(H1N1). Two amino acid changes at 142 and 144 positions compared with A/Yunnan/1145/2005 (H3N2). There was no change in influenza B viruses either Victoria-like B or Yamagata-like B virus, i.e . antigenic characteristics is analogous to B/shenzhen/155/2005 and B/tianjin/144/2005, respectively.

CONCLUSIONThe H1N1 and H3N2 influenza viruses had changing antigenic and genetic characteristics in 2006. Influenza virus types B did not change in 2006.

Amino Acids ; analysis ; China ; Hemagglutination Inhibition Tests ; Hemagglutinin Glycoproteins, Influenza Virus ; chemistry ; genetics ; immunology ; Influenza A Virus, H1N1 Subtype ; immunology ; isolation & purification ; Influenza A Virus, H3N2 Subtype ; immunology ; isolation & purification ; Influenza B virus ; immunology ; isolation & purification ; Time Factors

Pdm09 virus outbreak occurred in Mainland China in May 2009, a few months later, the prevalence of seasonal H1N1(sH1N1) influenza virus that already circulated in human for tens of years began to decline and disappeared afterwards. To identify the reason for the rapid decline of sH1N1 in mainland China, we sequenced the HA1 of sH1N1 during 2006-2011, and then analyzed the selective pressure in different phases. Our results showed before Pdm09 outbreak, the omega value was 0. 36 while after Pdm09 outbreak the omega value was 0. 28 and significant difference (t test, P<0. 05) was identified. We concluded that sH1N1 obtained stronger purifying selection after Pdm09 outbreak in China. This might one of the major reasons causing the disappearance of sH1N1 in human.
China ; Humans ; Influenza A Virus, H1N1 Subtype ; classification ; genetics ; isolation & purification ; Influenza, Human ; virology ; Phylogeny ; Seasons ; Selection, Genetic

The clinical throat swab specimen of an imported suspected case of influenza A (H1N1) was detec ted with real-time PCR, RT-PCR and subsequently confirmed by gene sequencing. The presence of influ enza A (H1N1) virus confirmed the first case with A (H1N1) infection in Mainland China.
China ; Humans ; Influenza A Virus, H1N1 Subtype ; classification ; genetics ; isolation & purification ; Influenza, Human ; virology ; Molecular Sequence Data ; Phylogeny

A new flu caused by a novel influenza A(H1N1) virus has spread over the United States, Mexico and more than 40 other countries. And because of the immediate global concern, WHO has announced that the current level of influenza pandemic alert is raised to phase 5, indicating approaching of an influenza pandemic. As patients suffering from the influenza A (H1N1) have the similar symptoms as patients with seasonal influenza, differential detection and identification of the influenza virus have to depend on specific laboratory tests. We have successfully developed a RT-PCR based method for detection of the influenza A (H1N1) virus, and had applied the method to detection of clinical samples.
Humans ; Influenza A Virus, H1N1 Subtype ; genetics ; isolation & purification ; Influenza, Human ; virology ; RNA, Viral ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; methods

OBJECTIVETo describe the feature of different age patients with A-H1N1.

METHODSCross-sectional study was performed in 95 patients who were confirmed to be infected with A-H1N1 from May, 2009 to July, 2009, in according to their age.

RESULTSThe average age of patients with A-H1N1 infection was 23.44 +/- 14.73. Accumulative prevalence in children and young adult reached 74.7% of total patients. There was a trend that the subclinical infection rate raised gradually from 0-15 years group to over 45 years group. The percent of lymphocyte in 0-15 years group was significantly higher than other age groups, P = 0.039. The average time of virus shedding were 6.5 +/- 2.10 days (from 2 days to 12 days) , and there were no significant difference in diverse age groups, P = 0.272. 13 out of 95 (13.7%) patients presented complications related with A-H1N1 infection, and 4 of 6 patients complicated with pneumonia were in the 0-15 years group.

CONCLUSIONThe distribution of age in A-H1N1 infection is markedly different from seasonal influenza, with more cases in school children and young adults and fewer cases in older adults. Flu-like symptoms in children were apparent and pneumonia was the major complication in children.

Adult ; Age Factors ; Asymptomatic Infections ; epidemiology ; Child ; Humans ; Influenza A Virus, H1N1 Subtype ; isolation & purification ; pathogenicity ; Influenza A virus ; immunology ; Influenza Vaccines ; immunology ; Influenza, Human ; classification ; pathology ; Prevalence