Avian influenza viruses (AIVs) H9N2 are in the course of reassorting into novel AIVs.

In 2013, two episodes of influenza emerged in China and caused worldwide concern. A new H7N9 avian influenza virus (AIV) first appeared in China on February 19, 2013. By August 31, 2013, the virus had spread to ten provinces and two metropolitan cities. Of 134 patients with H7N9 influenza, 45 died. From then on, epidemics emerged sporadically in China and resulted in several victims. On November 30, 2013, a 73-year-old woman presented with an influenza-like illness. She developed multiple organ failure and died 9 d after the onset of disease. A novel reassortant AIV, H10N8, was isolated from a tracheal aspirate specimen that was obtained from the patient 7 d after onset. This case was the first human case of influenza A subtype H10N8. On 4 February, 2014, another death due to H10N8 avian influenza was reported in Jiangxi Province, China.

[Correlation between acute schistosomiasis japonica and serum interleukin-33 levels].

OBJECTIVE: To study the function of interleukin-33 (IL-33) in the development of human acute schistosomiasis japonica by determining the serum IL-33 levels in acute schistosomiasis japonica patients. METHODS: Four patients with acute schistosomiasis japonica were recruited from schistosomiasis endemic lake areas, and 15 controls were recruited outside the schistosomiasis endemic areas. The demographic data and venous blood were collected from all the subjects. The serum IL-33 levels of all the subjects were tested by using enzyme-linked immunosorbent assay. All the results were statistically analyzed with Stata 10.0 software. RESULTS: The serum IL-33 levels of the patients with acute schistosomiasis japonica [517.33 (334.65, 1 056.88) pg/ml] were significantly higher than those of the controls [1.66(1.66, 6.35) pg/ml] (Z = -3.207, P = 0.001). The correlation coefficients between serum IL-33 levels and numbers of eosinophils, serum IL-33 levels and duration of infection were both 0.8 (P = 0.2). CONCLUSIONS: The serum IL-33 level is significantly elevated in the patients with acute schistosomiasis japonica, indicating that IL-33 may play a pro-inflammatory role in the acute stage of schistosomiasis japonica and participate in initiating the Th2 type immune responses between 7 and 9 weeks after the infection.

Antigenic and genetic variation in the hemagglutinins of H1N1 and H3N2 human influenza a viruses in the Shanghai area from 2005 to 2008.

Continued rapid evolution of the influenza A virus is responsible for annual epidemics and occasional pandemics in the Shanghai area. In the present study, the representative strains of A/H1N1 and A/H3N2 influenza viruses isolated in the Shanghai area from 2005 to 2008 were antigenically and genetically characterized. The antigenic cartography method was carried out to visualize the hemagglutination-inhibition data. Antigenic differences were detected between circulating A/H1N1 strains isolated from 2005 to 2006 and the epidemic A/H1N1 strains isolated in 2008, which were found to be associated with the amino acid substitution K140E in HA1. The present vaccine strain A/Brisbane/59/2007 is considered to be capable of providing sufficient immunity against most of the circulating A/H1N1 viruses isolated in 2008 from the Shanghai population. The study showed that there were significant antigenic differences between the epidemic A/H3N2 strains isolated in 2007 and 2008, suggesting that antigenic drift had occurred in the A/H3N2 strains isolated in 2008. The P194L mutation was thought to be responsible for the antigenic evolution of influenza A/H3N2 viruses isolated from Shanghai in 2008. Evidence of antigenic drift suggests that the influenza A/H3N2 vaccine component needs to be updated.

[Study on evolutionary origin of influenza A virus (H1N1) based on HA gene].

OBJECTIVE: To determine the evolutionary rate and divergence time of influenza A virus HA gene isolated recently worldwide pandemic and explore the origin and its transmission. METHODS: A total of 344 H1 sequences available in the GenBank (including 248 isolated from human, 84 from swine, 11 from avian, and 1 from ferret) and 7 isolated in Shanghai were collected. The nucleotide substitution rate and time to most recent common ancestor (tMRCA) was calculated using molecular clock theory and Bayesian Skyline Plot (BSP) based on Markov chain Monte Carlo. Then genetic phylogeny was constructed referring to posterior distribution. RESULTS: It was found that H1 sequences in the US from human, swine and avian were clustered significantly with swine H1 ones from Asia phylogenetically (Cluster US). The second cluster (Cluster Eurasian Human) nearly consisted of human H1 sequences isolated in other regions. The third cluster (Cluster Eurasian Animal) consisted of swine and avian H1 sequences from China and Italy respectively. As for all the H1 sequences, the evolutionary rate was of 2.57 x 10(-3) substitutions/site per year averagely (95% Highest Posterior Density: 1.96 x 10(-3) - 3.03 x 10(-3)/site per year). The estimated dates for tMRCA of human H1 in Europe and swine H1 in the mainland of China were the earliest, with the corresponding rates of 6.46 x 10(-3)/site per year and 0.97 x 10(-3)/site per year respectively. The tMRCAs of human and swine H1 sequences from the US were similar, with the rates of 5.86 x 10(-3)/site per year and 5.02 x 10(-3)/site per year. CONCLUSION: The present flu outbreak was possibly induced by long-term circulation of influenza A virus (H1N1) in human population and swine herds in America. There was no evidence proving that influenza virus in China involved in the present outbreak.

[Type and subtype distribution of influenza virus and genetic evolution of hemagglutinin in Shanghai area in duration of 2004 - 2008].

OBJECTIVE: To analyze the type and subtype distribution of influenza virus and the genetic evolution of hemagglutinin (HA) in Shanghai area during 2004 to 2008. METHODS: All 962 throat swabs were collected from influenza-like patients in 5 influenza sentry hospitals and influenza outbreaks. Influenza viruses were isolated in MDCK cell lines, and then viral types and subtypes were identified. The HA of influenza A isolates selected by outbreak or sporadic patients in different areas and epidemic seasons were sequenced and analyzed by phylogenetic trees. RESULTS: A/H3N2, accounting for 54.9% (162/295), was the dominate subtype in recent years, but less popular in the end of 2005 to the middle of 2006 with 0% (0/16)and 23.5% (8/34) of positive specimen, respectively. There were more A/H1N1 isolates in 2005 - 2006 with 21.4% (12/56), 43.8% (7/16) and 76.5% (26/34) of positive specimen, respectively, but declined obviously in 2007 - 2008 accounting for only 0% (0/44) and 5.0% (7/139). Influenza B virus was more popular in 2004 to 2005 with 42.9% (24/56) and 56.2% (9/16), respectively, and not isolated from 2006 to 2007, then increased in 2008 accounting for 34.5% (48/139). Phylogenetic tree of HA showed that A/H1N1 isolates in the same year clustered from 2005 to 2008, and most A/H3N2 isolated were homologous in the same year during 2004 - 2008 while some were inserted to the clusters of near years and more distinguished sequences appeared. A/H1N1 and A/H3N2 isolates were all similar to the vaccine strains recommended by WHO. CONCLUSION: The distribution of influenza type and subtype kept on changing each year, but A/H3N2 dominated in most years. A/H1N1 and A/H3N2 in the same year clustered, but some A/H3N2 of near years were and evolved faster with more distinguished strains appeared in same interval. Generally, HA of influenza A isolates in Shanghai during 2004 to 2008 were similar to the WHO reference strains.

[Epidemiological characteristic of Varicella and Varicella-Zoster virus genotype in Minhang District of Shanghai].

OBJECTIVE: To describe the epidemiological characteristic of varicella, and to find out the genotype of the prevalent Varicella-Zoster Virus (VZV) in Minhang, Shanghai. Analysis was carried out during Nov. 2007 to Apr 2008. METHODS: The data collected from the National Diseases Reporting Management System (NDRS) and Provincial Disease Surveillance Point System (DSP). Samples from herpes of patients were also collected to isolate VZV in Vero and Vero-E6 cell lines, then to detected if cytopathic effect (CPE) by PCR, and finally to identify the genotype by sequence analysis. RESULTS: 29 outbreaks of 271 cases occurred in Minhang during Nov. 2007 to Apr. 2008, and attack rate was 0.42% in average. Among the cases, 37 (13.65%) had vaccinated before getting varicella. Most cases occurred in November and December, and clustered in some areas with population migrant frequently. 2 VZV strains were isolated and identified as genotype J. CONCLUSION: The prevalence of varicella in Minhang was serious. The varicella prevention and control among schools and kindergartens should be strengthened by propaganda and vaccination.

[Sequence analysis on measles viruses isolated in Shanghai in 2005].

OBJECTIVE: To ascertain the genetic characterization and genotype of measles viruses isolated in Shanghai region, in 2005. METHODS: Measles virus was isolated from throat swab specimens collected from suspected measles cases and 450 bp fragment of C terminus of nucleprotein (N) gene was amplified by RT-PCR. Sequence analysis was conducted to ascertain the genotype and to compare the difference of nucleotide with other measles virus strain published in GenBank. RESULTS: 4 measles viruses were isolated from 10 throat swab specimens, and the sequence analysis indicated that they belonged to H1 genotype. The homogeneity of 450 nucleotides in the C terminal of the N gene was at 98%-98.2% as compared to H1 genotype (China93-7). They differed from genotype H2 (China94-1) at 6.4%-6.9% and from genotype A (Edmonston) at 6.7%-6.9%, from measles vaccine (Shanghail91) at 7.6%-8.0%. They differed from the other measles viral strain isolated in China in 1993 - 2005 at 0.2%-3.7%. The variation within 4 isolated measles viruses was at 0.7%-1.3%. CONCLUSION: It was H1 genotype measles viruses,which are the native viruses in China that led to the outbreak of measles in Shanghai, in 2005.

[Application of gene sequence cluster in research for H3 antigenic evolution of influenza A virus].

OBJECTIVE: Gene sequence data were clustered to explore evolution lineages of H3 antigen of influenza A virus. METHODS: All data of H3 RNA sequence in NCBI Genbank and Influenza sequence database were downloaded and aligned in ClustalX while two step cluster method were applied to explore the data. RESULTS: All sequences were aggregated into ten clusters, while seven of them mainly were human virus. Human virus and avian/other mammal virus were separated into different clusters distinctively, but coexisted into same clusters with swine virus. Time and host distribution were very distinctive in these clusters, but no geographic distribution features were found. CONCLUSION: With the interaction of human immunity system, H3 antigen mutated significantly every 5 - 7 years, and the speed of mutation had accelerated with the application of influenza vaccines in recent years. Mean while, human and swine influenza virus were not separated distinctly between clusters indicating that they had short inheritance distance. Result showed again that swine served as the mixer for antigenic recombination of different influenza virus.