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 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 understand the epidemiological characteristics of influenza outbreaks in China from 2005 to 2013.

METHODSThe data of influenza-like illness outbreaks involving 10 or more cases were collected through Public Health Emergency Management Information System and National Influenza Surveillance Information System in China, and the influenza outbreaks were identified according to the laboratory detection results. Descriptive epidemiological analysis was conducted to understand the type/subtype of influenza virus and outbreak time, area, place and extent.

RESULTSFrom 2005 to 2013, a total of 3 252 influenza-like illness outbreaks were reported in the mainland of China, in which 2 915 influenza outbreaks were laboratory confirmed, and influenza A (H1N1) pdm09 virus and influenza B virus were predominant. More influenza outbreaks were reported in the influenza A (H1N1) pandemic during 2009-2010. Influenza outbreaks mainly occurred during winter-spring, and less influenza outbreaks occurred in winter and summer vacations of schools. More influenza outbreaks were reported in southern provinces, accounting for 79% of the total. Influenza outbreaks mainly occurred in primary and middle schools, where 2 763 outbreaks were reported, accounting for 85% of the total. Average 30-99 people were involved in an outbreak.

CONCLUSIONA large number of influenza outbreaks occur during influenza season every year in China, the predominant virus type or subtype varies with season. Primary and middle schools are mainly affected by influenza outbreaks.

China ; epidemiology ; Disease Outbreaks ; Humans ; Influenza A Virus, H1N1 Subtype ; isolation & purification ; Influenza B virus ; isolation & purification ; Influenza, Human ; epidemiology ; virology ; Population Surveillance ; Schools ; Seasons

OBJECTIVETo study the epidemic situation and dominant strain of influenza in children with acute respiratory infection (ARI) during Flu season from Oct. 2005 to Mar. 2006 in Taiyuan.

METHODSMadin-darby canine kidney (MDCK) cell culture and hemagglutination inhibition (HI) assay were used to isolate and identify type A influenza viruses (H1N1 and H3N2) and B influenza viruses from clinical samples collected from outpatients who visited the Department of Pediatric because of ARI from Oct. 2005 to Mar. 2006. Oct. 2005 and Mar. 2006, we collected 415 blood samples from children and adults to detect the influenza virus antibody titers by HI test to exclude respiratory diseases.

RESULTS7 strains of H1N1 were isolated from 87 clinical specimens, with a positive rate of H1N1 as 8.04%. Out of 415 blood samples being collected, the positive rates and the geometric mean titer of H1N1 antibody Mar. 2006 were significantly higher in 0-3, 3-7 and 7-18 year-olds than Oct.2005.

CONCLUSIONH1N1 epidemic influenza did occur among children in winter and spring of 2005--2006 in Taiyuan city.

Adolescent ; Animals ; Antibodies, Viral ; blood ; Cell Line ; Child ; Child, Preschool ; China ; epidemiology ; Dogs ; Hemagglutination Inhibition Tests ; Humans ; Infant ; Influenza A Virus, H1N1 Subtype ; isolation & purification ; Influenza A Virus, H3N2 Subtype ; isolation & purification ; Influenza B virus ; isolation & purification ; Influenza, Human ; epidemiology ; Population Surveillance