Bing du xue bao = Chinese journal of virology最新文献

We wished to explore the ability of the meq-deleted Marek's disease virus (MDV) vaccine strain SC9-1 to acquire the meq gene from the MDV wild strain Md5 by recombination. Chicken embryo fibroblast cells (CEFs) were co-infected with the SC9-1 vaccine virus and Md5 virus, passaged to third generation, and viral DNA was extracted from a single plaque in the cell culture. Specific pathogen-free chickens pre-immunized with the SC9-1 vaccine virus were infected with the Md5 virus. Viruses were isolated from chickens-at different time points. Then, viral DNA was extracted from a single plaque and amplification by polymerase chain reaction done to identify isolated viruses. The flip recombina-se sites (FRT) residue region was cloned and sequenced. Results showed that the isolated viruses in cultured CEFs or in chickens were the SC9-1 or Md5 virus, and recombinant viruses were not detected. Sequence analyses revealed that the homology of the FRT residue sequence between the isolated virus and parent virus was 100%. Therefore, there is little chance that SC9-1 can acquire the meq gene from Md5 by natural recombination. Also, the meq-gene knockout region had good genetic stability during serial passages in vivo and in vitro.

Digital polymerase chain reaction (dPCR) is a new method for absolute quantification of nucleic acids. The dPCR reaction solution is divided into numerous partitions followed by independent amplification. Target copy number is counted using statistical analyses of positive signals. in contrast to quantitative PCR, a standard curve is not necessary for dPCR. Here, we reviewed the development, principles, and applications of dPCR.

We wished to study the dynamic change in variation of rubella viruses circulating during 1999-2015 in mainland China at the molecular level. Molecular evolution of Chinese rubella viruses collected during 1999 ~ 2015 was analyzed according to a surveillance database of measles/rubella laboratory networks in China. A total of 1737 rubella viruses were obtained from 20 of 31 provinces (except Xinjiang and Tibet) during 1999 ~ 2015. Four genotypes (1E, IF, 2A, 2B) were detected. The genotype-1E rubella virus was detected first in 2001. Subsequently, genotype 1E became the predominant genotype circulating during 2001~2013, and could be divided into two closely related clusters (A (2004-2015) and B (2001-2009)). However, the detection rate of the genotype-1E rubella virus decreased year-by-year from 2011, and reached the lowest level (1. 3%) in 2015. The genotype-1F rubella virus was restricted geographically to China, and no longer found after 2002; presumably its circulation in China was interrupted. All genotype-2A rubella viruses were derived from vaccine-related cases. At least four genotypes of 2B rubella viruses (lineage 1 ~ 4) circulated in mainland China during 2000 ~ 2015. The genotype-2B rubella virus was detected sporadically and was in a weak position until 2010. However, the detection rate of imported genotype-2B rubella viruses (lineage 3) was increased and became the predominant genotype during 2014~2015. Through the study of 16 consecutive years in mainland China, the evolution and epidemic situation of the rubella virus was obtained to aid virology surveillance for rubella control in China.

We wished to develop a simple method to amplify and sequence the whole genome of the highly pathogenic avian influenza A ( H5N6 ) virus. Hemagglutinin ( HA ) gene sequences of A ( H5), neuraminidase (NA) gene sequences of A (N6), as well as the internal gene sequences of subtype A (H5N1) and A (H9N2) influenza viruses of the-previous 5 years were downloaded from GenBank and GISAID, and individual genes were aligned. Thirty-two primer pairs targeted to conserved regions of these gene sequences were designed and validated. After optimization, the whole genome sequence of nine influenza A(H5N6) viruses isolated from infected humans and those circulating in the environment were obtained-with the 32 primer pairs. Viruses isolated from human respiratory specimens were amplified to produce distinct products of the polymerase chain reaction. When tested on viruses. isolated from environmental swabs, few primer pairs produced specific and non-specific products. A Sanger protocol for generating the whole genome sequence of the highly pathogenic avian influenza virus A (H5N6) was established and shown to be a rapid and easy method to provide data for phylogenetic analyses of this virus.

We wished to characterize the envelope protein coding gene of the hepatitis-C virus (HCV) from Chinese patients and prepare HCV pseudoparticles (HCVpp) of subtype 3b. Two of the HCV genotype 3b envelope protein coding genes (C27, C30) were cloned from Chinese HCV patients followed by sequencing analyses. Then, two envelope protein expression plasmids were constructed and characterized by western blotting. HCVpp were prepared and target cells infected in vitro. Results showed that the sequences of nucleotides and amino acids from two HCV subtype 3b envelope protein encoding genes (C27, C30) had high homology (98. 5% and 98. 2%, respectively) and had a close phylogenetic relationship with the international reference strain 3b TrKj. Ten amino-acid sites were substituted in the envelope protein coding region of C27 and C30. Expression of the C27 envelope protein was significantly higher than that of HCV subtype 1 (Conl) and C30. The corresponding HCVpp infectivity in vitro was also significantly different, whereby C27 could be used to prepare HCVpp subtype 3b with high infectivity. In conclusion, two envelope protein encoding genes of HCV subtype 3b were sequenced and their expression in vitro investigated. This is the first report on preparation of HCVpp subtype 3b with high infectivity. This study might provide an effective tool for HCV research and development of a vaccine for HCV.

Non-coding RNAs (ncRNAs) are a class of RNAs that have no potential for protein coding. Increasing numbers of studies have provided strong evidence that ncRNAs play important roles in regulation of various biologic processes, including interactions between viruses and the host. Influenza viruses remain a major, threat to human health and animal livestock. Interactions between the host and mutations of influenza viruses are very complicated. Recent data have shown that many ncRNAs play important roles in the interactions between influenza viruses and the host. Understanding the fuiction of these ncRNAs in the infection and replication of influenza viruses is very important to elucidate the pathogenesis of these viruses, and to provide strategies for the prevention and control of influenza. This review summarizes the ncRNAs that act as key regulators of interactions between the host and influenza viruses.

Autoregressive integrated moving average (ARIMA) model was used to predict the monthly reported severe cases of hand-foot-mouth disease(HFMD) in China to provide a reference for prevention and control of HFMD and the application of ARIMA in of ARIMA in HFMD and other infectious diseases. On the basis of time series supplied by the monthly reported severe cases of the national HFMD from 2010 ~ 2015, ARIMA model was established with the actual cases of HFMD from January to September 2016 as the validated data and with the comparison of ARIMA model based on the data from 2010-2014- The models based on the 2010~2014 and 2010~2015 data of monthly reported severe cases of HFMD in China are ARIMA(1,1,0,) (2, 1,0)(12),ARIMA(0,1,1,) (2,1,0)(12) respectively. The comparison of two models shows that the average of the relative error decreases with the accumulated data and does not do the same with the shorter time of predication. Different time series may have different ARIMA models as for the same infectious diseases. It is needed to be further verified that the more data are accumulated, the more shorter time of predication is, the more-smaller the average of the relative error is.

We wished to study the genetic diversities and mutations of the basic core promoter (BCP) and pre-C region of the hepatitis B virus (HBV) in liver-cancer tissues. One hundred and ninety-two tissue samples were collected from patients suffering from hepatocellular carcinoma (HCC) and HBV infection in 2015 in Xijing Hospital. Twenty-one cases were selected, of which direct sequencing of the polymerase chain reaction (PCR)-amplified products of BCP/pre-C region was unsuccessful. Cloning and sequencing allowed the DNA sequences of the BCP/pre-C region to be analyzed. Sequencing showed infection with mixed mutants of HBV in 37. 89% of HBV-positive HCC patients, and that HBV DNA in each sample contained 2 ~ 11 types of mutations.. The mutation rate of deletion and insertion was 80. 95%. Other mutations in descending order by mutation rate were a: A1762T/G1764A combined mutation (90. 48%); G1756C/T1803A/A(1757 ~ 1765)/A (1824 ~ 1832) combined mutation (80. 95%); T1753C/A1762T/ G1764A combined mutation (57. 14%); A1762T/G1764A/G1896A combined mutation (42. 86%); G1756C/Δ(1757~176.5) combined mutation,(28. 57%); T1753C/A1762T/G1764A/G1896A combined mutation (23. 81%). The sequencing failure of PCR products may have been correlated directly with the deletion and insertion mutations of HBV DNA. These findings lay the foundation for further studies on HBV mutations, persistent infection, and the mechanism of personalized medicine.

We compared the effect of oseltamivir on the hemagglutination (HA) test and hemagglutinin inhibition (HI) test of the influenza A(H3N2) virus in China to obtain the "true" HA titer and antigenic variation. A total of 395 influenza H3N2 strains isolated in mainland China from October 2014 to May 2015 were analyzed with HA and HI tests, with or without oseltamivir.. Gene sequencing was undertaken for selected viruses, and the amino-acid sequence of neuraminidase (NA) protein was compared with the vaccine strain. In the HA test in the presence of oseltamivir, the HA titer was unchanged in 44. 8%, decreased in 43. 8%, and increased in 11. 4% of tested strains. In the presence of oseltamivir, the proportion of viruses similar to A/TX/50/2012 egg isolates was significantly higher, and the proportion of viruses similar to A/SZ/9715293/2013 cell isolates significantly lower, than the proportion obtained from the test without the presende of oseltamivir. A significant difference was detected between the tests with or without oseltamivir. In A/TX/50/2012 cell isolates and A/SZ/9715293/2013 egg isolates, no significant difference was detected between the tests with or without oseltamivir. Nineteen selected strains' of influenza A ( H3N2) were sequenced, and the amino-acid sites were compared with A/TX/50/2012 egg isolates. Five strains had a more-than-fourfold decrease in HA titer when addition of oseliamivir showed no common mutation in amino acids, whereas the A/Shandong Laicheng/119/2015 strain had a D151G mutation and the A/Jilin Tiexi/1194/2015 strain had a V4121 and T434A mutation in the NA protein. The strain had a two-to-fourfold decrease in HA titer when addition of oseltamivir showed 126T, G93S, V1491, N234D, T267K and S416G mutations in NA protein.. These data show that, for recent circulating influenza H3N2 viruses, the presence of oseltamivir can be used to obtain more accurate HA and HI titers for antigenic analysis and vaccine evaluations.

We studied the molecular epidemiology of echovirus 30 in sporadic cases of viral encephalitis in Longyan City, Fujian, China, from 2011 to 2014.Specimens of cerebrospinal fluid from patients diagnosed with viral encephalitis or infection of the central nervous system were collected. Viruses were isolated by cell culture. Identification of the echovirus 30 serotype and genetic analyses were undertaken. Amplification of virus protein(VP)-1gene sequences was done by reverse transcription-polymerase chain reaction. A total of 168 strains of enterovirus were isolated in 608 cases from 2011 to 2014,of which 60 strains were echovirus 30.The epidemic "peak" of echovirus 30 was from June to August. The age range of patients was wide, with 65% of cases under 10 years of age. Clinical manifestations were pyrexia, headache and vomiting.Cerebrospinal fluid was clear, and the number of cells and protein was increased. The epidemic strains in Longyan City from 2011 to 2014belonged to the "h" genotype, and there were two transmission chains. Compared with the viral encephalitis strains from the outbreak in Fujian Province in 2011,they were highly homologous, but a new amino-acid variation of VP1 protein I 120 V was found in Longyan City strains from 2014.The viral encephalitis strains from the outbreak in Fujian Province in 2011 were present in Longyan City strains, and two transmission chains are still circulating,but there were new mutations in the virus strains from 2014.Continuous monitoring will aid:(i)early detection of viral variants that may accumulate;(ii)assessment of the risk of epidemics.