A survey of the 2014 dengue fever epidemic in Guangzhou, China.

In 2014, a serious dengue outbreak in Guangzhou occurred, consisting of 37 354 laboratory confirmed cases of infection. In this study, the clinical picture of dengue fever due to dengue virus (DENV) type 1 in Guangzhou was described. Clinical and laboratory data collected by studying 726 sera of suspected clinical cases from hospitals and 328 sera of healthy persons from two residence communities were analyzed during the outbreak, and 484 patients were diagnosed with an acute dengue infection. Fever, headache, congestion of the throat, and myalgia were the most typical symptoms in DENV-infected patients. Thrombocytopenia, leukopenia, and an increase in liver enzymes were significantly more common in the infected patients than in the healthy controls. Fourteen cases of silent infection were discovered among the 328 healthy persons, suggesting a DENV inapparent infection rate of 4.27% among healthy individuals. The data obtained by analyzing 212 positive sera with three methods indicated different results with different detection methods. DENV RNA should be used for early diagnoses during days 1-6 after symptom onset, immunoglobulin M (IgM) can be easily recognized after four days have passed since symptom onset and DENV isolation has a peak positive rate during days 1-3 after the onset of symptoms. A phylogenetic analysis of viral NS1 gene sequences from this outbreak indicated that the predominant isolates could be categorized as DENV-1 genotype III and had the highest homology with the India genotypes from 2009 to 2011. However, this analysis also revealed a co-epidemic of the 2013 Zhongshan and 2003 Singapore genotypes, both belonging to DENV-1 genotype I, which suggested multiple geographic origins for the 2014 epidemic of dengue 1 strains in Guangzhou.

[Diagnostic value of magnetic resonance spectroscopy and intraoperative magnetic resonance imaging in the treatment of brain abscesses].

OBJECTIVE: To evaluate the diagnostic value of magnetic resonance spectroscopy (MRS) and the role of intraoperative magnetic resonance imaging (iMRI) in the treatment of brain abscesses by aspiration and drainage. METHODS: From November 2009 to June 2013, Forty-one brain abscess patients were evaluated. MRS was employed to acquire the metabolic information and assist in the differential diagnosis of brain abscesses showing lactate cytosolic amino acids (AAs) with/without succinate, acetate, alanine and glycine on MRS. Diffusion-weighted imaging (DWI) was also helpful. Eleven single deep-seated abscesses underwent aspiration and drainage with 1.5 T iMRI and neuronavigation system. RESULTS: Forty-one brain abscesses were all diagnosed correctly. Ten single deep-seated abscesses underwent aspiration and drainage with 1.5 T iMRI and neuronavigation system successfully with just one puncture. One deep-seated abscess with thick-walled was punctured thrice before achieving success because of aspirated needle sidesliping. All 11 deep-seated abscess cases were cured and were also confirmed by follow-up. None of them suffered from significant complications, such as intracranial bleeding or new neurological deficit. CONCLUSION: MRS may acquire the metabolic information, confirm the presence of AAs with/without succinate, acetate, alanine and glycine and assist in the differential diagnosis of brain abscesses. iMRI system can help detect aspirated needle sidesliping and correct it in time to improve the cure rate, especially for single deep-seated brain abscess with a thick wall.

[Screening and identification of dengue virus type 2-specific antigens].

OBJECTIVE: To screen and identify dengue virus type 2 specific antigens and establish an enzyme-linked immunosorbent assay (ELISA) for detecting dengue virus type 2 antibody. METHODS: Using the bioinformatic software DNAstar and ANTHEPROT, we analyzed the hydrophilicity, flexibility, surface probability and antigenicity of dengue virus type 1-4, Japanese encephalitis virus, and Yellow fever virus M and E protein amino acid sequences, and also evaluated the influence of secondary structure. The specific epitopes of dengue virus type 2 were predicted according to the epitope location and amino acid sequence similarity, and the epitope conservation was assessed using the sequence information of different dengue virus type 2 strains in GenBank. Based on the results of bioinformatic analysis, 5 specific epitopes were amplified and inserted into the prokaryotic expression vector pET32a, which were transferred into E. coli Rosetta (DE3) for expression of the proteins. SDS-PAGE and Western blotting were used to identify the expressed proteins and test their antigenicities. The antigen selected by Western blotting was used to establish the ELISA system for dengue virus type 2 antibody detection. RESULTS: Bioinformatic analysis predicted 8 possible dengue virus type 2 specific epitopes, and 6 of them were efficiently expressed in E. coli. Western blotting confirmed 1 dengue virus type 2 specific antigen, the ELISA system for dengue virus antibody detection was successfully established using this specific antigen. CONCLUSION: We have obtained a dengue virus type 2 specific antigen and established an ELISA system for detection of dengue virus type 2 antibody.

Molecular epidemiology of dengue viruses in southern China from 1978 to 2006.

To investigate molecular epidemiology of dengue viruses (DENV) in southern China, a total of 14 dengue isolates were collected in southern China during each epidemic year between 1978 and 2006 and their full-length genome sequences were obtained by using RT-PCR method. The E gene sequences from additional 6 dengue fever patients in Guangzhou in 2006 were also obtained by using RT-PCR method. Combined with DENVs sequences published in GenBank, phylogenetic analysis and recombination analysis were performed. One hundred and twenty-five E gene sequences and 60 complete genome sequences published in the GenBank were also involved. Phylogenetic analysis showed that there was a wide genetic diversity of DENVs isolated in southern China. DENV-1 strains exist in almost all of the clades of genotype I and IV except the Asia 1 clade of genotype I; DENV-2 stains are grouped into four of the five genotypes except American genotype. DENV-4 strains are grouped into 2 genotypes (I and II). Phylogenetic analysis also showed that all DENV-4 isolates and two DENV-2 isolates were closely related to the prior isolates from neighboring Southeast Asia countries. The DENV-1 strain isolated during the 2006 epidemic is highly homologous to the strains isolated during the 2001 epidemic.Recombination analysis showed no inter-serotype recombination, but 22 intra-serotype recombination events were found across the 32 complete genomes of all Chinese isolates. The study suggested that dengue fever epidemic in Southern China over the past 30 years presented two important modes, 1) imported-cases-induced endemic prevalence; 2) endogenous epidemic outbreak with natural epidemic focus. Recombination may play an important role in dengue virus evolution and adaptation.

Real-time PCR for detecting circulating dengue virus in the Guangdong Province of China in 2006.

Dengue virus (DENV) causes a wide range of diseases in humans, from the acute febrile illness dengue fever (DF) to life-threatening dengue haemorrhagic fever/dengue shock syndrome. We developed four real-time quantitative PCR assays for each serotype of DENV based on computational analysis. These assays had high sensitivity and specificity without cross-reactivity for the four serotypes. To evaluate the performance of these assays in detecting and typing the virus in clinical samples, we analysed 64 serum samples from Guangdong during 2006. The results showed that 71 % of those samples were positive by the DEN-1 assay. The DENV assay results, in agreement with the serological tests and sequencing analysis, showed that the pathogen resulting in the DF explosion in Guangdong in 2006 belonged to DEN-1. Compared to the serological assays, the real-time PCR assays that we developed were much more sensitive in the 1-3 days after onset of the symptoms.

[Establishment of a tight tetracycline-controlled HCV-C double transgenic mouse model].

OBJECTIVE: To develop a tight tetracycline-controlled HCV-C double transgenic mouse model. METHODS: By crossbreeding of ApoE-rtTA-tTS transgenic mice with TRE-HCV-C transgenic mice, the double transgenic mice were produced in the F1 generation. The presence of HCV-C and tTS gene in the F1 generation was confirmed by PCR, followed by further identification and quantification of the transgene using Southern blot hybridization. The expression of HCV-C in the liver of the mouse model was detected immunohistochemically. RESULTS AND CONCLUSION: Two transgenic mice were obtained, which contained ApoE-rtTA-tTS and TRE-HCV-C genes in the genome. Five founders contained HCV-C gene as confirmed by PCR and Southern blot hybridization. The tight tetracycline-controlled system may facilitate further study of HCV-C gene expression and gene therapy of hepatic cellular carcinoma.

[Study on DNA fingerprinting of Mycobacterium tuberculosis strains isolated in Southern Chinese army by IS6110-restriction fragment length polymorphism].

OBJECTIVE: To study the correlation between DNA fingerprinting of Mycobacterium tuberculosis (MTB) stains isolated from the Chinese army in the south and from local residents, and to investigate the molecular epidemiological characteristics of tuberculosis (TB) in the army, for the sake of TB prevention in the army. METHODS: MTB DNA was digested with restriction endonuclease PvuII and electrophoresed in agarose gel, after Southern Blotting, the membrane was hybridized with a 245 bp fragment of IS6110 which labeled [alpha(32)P]-dCTP as probe. Finally, a restriction fragment length polymorphism (RFLP) patterns was shown, and analyzed logestic with epidemiological data from the patients. RESULTS: A total number of 185 TB strains were detected and the IS6110 copy numbers ranged from 1 - 22. No significant difference was found in the IS6110 copy numbers between patients from army and local patients. IS6110 copy numbers of TB strains in army patients were centered in 6 - 20, however, with 7 - 20 copies in local TB patients. The TB strains were dispersed into 8 groups and the majority of TB strains in both army and local patients was centered in groups I, II, III. The distribution of DNA fingerprint for drug resistance TB strains was significantly different from those for sensitive strains. No different distribution of among groups was found regarding BCG history. CONCLUSIONS: The genetics of TB stains were roughly the same between the army patients and local ones, but there was a strong correlation in the gene levels. Data suggested that a close connection should be considered on TB prevention and treatment for TB patients in the army and local residents.

[Study on molecular epidemiology of Mycobacterium tuberculosis in Chinese army with PCR amplified fingerprinting methods].

OBJECTIVE: Typing of Mycobacterium tuberculosis strains and epidemiological studies in the army of southern China to provide scientific basis for prevention of pulmonary tuberculosis. METHODS: A rapid fingerprinting of M. tuberculosis strains method by polymerase chain reaction (PCR) with outward-directed primers that designed to the ends of the insertion sequence IS6110 was developed, and to analyze the relationship between the polymorphism of DNA fingerprinting and epidemiology of M. tuberculosis. RESULTS: One hundred and fifty-four M. tuberculosis detected were classified into eight types according to their characters of PCR amplified fingerprints. The main types were type I (36.4%), type II (31.8%), and type III (21.4%), while other types were less than 4 percentage. In those main type groups, patients aged 20 to 29 and 30 to 39 took up 31.8% and 27.9% respectively. For those main types, the distribution of those types in the first treated patients showed significant difference compared with that in the retreated patients, and the rate of drug-resistance was also statistically different. However, the distribution was not statistically significant to history of BCG vaccination and patients living in urban or rural area. The main drug-resistant strains were only Isoniazid-resistant or Rifampin-resistant strains, while the drug-resistant strains were 44.4%, 29.6% and 14.8% respectively in type I, type II and type III. CONCLUSION: PCR fingerprinting was a rapid, precise, sensitive, specific method to type M. tuberculosis, and could be used to study the epidemiology of tuberculosis; The prevalence of tuberculosis was primarily due to the transmission of type I, type II and type III in the army being studied from Southern China, to suggest that surveillance needs to be strengthened.