[The world's first malaria vaccine: Hope and challenge]

The RTS,S/AS01 is a subunit malaria vaccine against the pre-erythrocytic stage of Plasmodium falciparum. After over 30 years of research and development and clinical trials, this vaccine has been recommended by the WHO for use among children living in highly malaria endemic areas. Although the RTS, S/AS01 vaccine suffers from problems of a low protective efficacy (about 30%), need of four doses and short duration of protective immunity, this malaria vaccine is expected to save tens of thousands of children's lives, and avoid tens of millions of malaria cases annually, because there have been tens of thousands of childhood deaths due to malaria recently. The introduction of the RTS, S/AS01 vaccine is therefore, widely accepted as a milestone in the history of battle against malaria, which brings a hope to contain malaria and even eventually eliminate malaria. Although there are still multiple challenges in the development of a satisfactory malaria vaccine, the success of the RTS, S/AS01 malaria greatly facilitates the progress towards the development of parasitic disease vaccines, and a more perfect malaria vaccine deserves expectations.

[A novel isothermal amplification assay improves the capability for the field rapid detection of parasitic diseases]

With the rapid development of molecular biology, the isothermal amplification technique has been used for the nucleic acid detection of parasites and other pathogens due to its high efficiency and rapid and simple procedures, and has become an important tool to promote the field detection and control of parasitic diseases. Recombinase-aided isothermal amplification assay (RAA), a novel isothermal amplification technique, which is simple and easy to perform, rapid for field detection, no need for high-end equipment, and rapid field detection, may amplify the target gene fragments within 5 to 20 min under an isothermal condition (usually 37 to 42 ℃) and achieve a real-time observation of the amplification results. RAA has been successfully employed for the nucleic acid detection of a wide range of parasites and other pathogens to date, and has shown a high sensitivity and specificity. Notably, such an assay is suitable for the large-scale field detection in non-lab environments, and is therefore considered to have a potential value of application in rapid field detections.

Epidemiological and viral genome characteristics of the first human H7N9 influenza infection in Guangdong Province, China

BACKGROUND

The first H7N9 human case in south of China was confirmed in Guangdong Province on August 2013, outside of the typical influenza season. For investigating the H7N9 virus source and transmission in the local community, we analyze the epidemiology and genome features of the virus isolated from the first human infection detected in Guangdong Province.

METHODS

The data including medical records, exposure history and time line of events for the H7N9 patient and close contacts was collected. Variation and genetic signatures of H7N9 virus in Guangdong was analyzed using ClustalW algorithm and comparison with mutations associated with changes in biological characteristics of the virus.

RESULTS

The female patient had a history of poultry exposure, and she was transferred from a local primary hospital to an intensive care unit (ICU) upon deterioration. No additional cases were reported. Similar to previous infections with avian influenza A (H7N9) virus, the patient presented with both upper and lower respiratory tract symptoms. Respiratory failure progressed quickly, and the patient recovered 4 weeks after the onset of symptoms. Genome analysis of the virus indicated that the predicted antigen city and internal genes of the virus are similar to previously reported H7N9 viruses. The isolated virus is susceptible to neuraminidase (NA) inhibitors but resistant to adamantine. Although this virus contains some unique mutations that were only detected in avian or environment-origin avian influenza A (H7N9) viruses, it is still quite similar to other human H7N9 isolates.

CONCLUSIONS

The epidemiological features and genome of the first H7N9 virus in Guangdong Province are similar to other human H7N9 infections. This virus may have existed in the environment and live poultry locally; therefore, it is important to be alert of the risk of H7N9 re-emergence in China, including emergence outside the typical influenza season.

[Generation high yield vaccine strain wholly derived from avian influenza viruses by reverse genetics]

Highly pathogenic avian influenza A (HPAI) viruses of the H5N1 subtypes caused enormous economical loss to poultry farms in China and Southeastern Asian countries. The vaccination program is a reliable strategy in controlling the prevalence of these disastrous diseases. The six internal genes of the high-yield influenza virus A/Goose/Dalian/3/01 (H9N2), the hemagglutinin (HA) gene of A/Goose/HLJ/QFY/04 (H5N1) strain, and the neuraminidase gene from A/Duck/Germany/1215/73 (H2N3) reference strain were amplified by RT-PCR technique. The HA gene was modified by the deletion of four basic amino acids of the connecting peptide between HA1 and HA2. Eight gene expressing plasmids were constructed, and the recombinant virus rH5N3 was generated by cells transfection. The infection of chicken embryos and the challenge tests involving chickens demonstrated that the recombinant H5N3 (rH5N3) influenza virus is avirulent. The allantoic fluids of rH5N3-infected eggs contain high-titer influenza viruses with hemagglutination unit of 1:2048, which are eight times those of the parental H5N1 virus. The rH5N3 oil-emulsified vaccine could induce hemagglutination inhibition (HI) antibodies in chickens in 2 weeks post-vaccination, and maximum geometric mean HI-titer were observed 4 approximately 5 weeks post-vaccination and were kept under observation for 18 weeks. The rH5N3-vaccinated chickens were fully protected against morbidity and mortality of the lethal challenge of the H5N1 HPAI viruses, A/Goose/Guangdong/1/96 and A/Goose/HLJ/QFY/04, which had 8 years expansion and differences among multiple amino acids in HA protein. The N3 neuraminidase protein marker makes it possible to distinguish between H5N1 infected- and H5N3 vaccinated animals.

Gender based differences in patients with acute coronary syndrome: findings from Chinese Registry of Acute Coronary Events (CRACE)

BACKGROUND

Many studies have examined gender related differences in the presenting symptoms, management and prognosis of patients with acute coronary syndrome (ACS). Much data are available from industrialized countries, in which ACS is a major cause of morbidity and mortality, but relatively little information has been obtained from China, where an epidemic of cardiovascular disease is starting to emerge. The purpose of this study was to assess the differences in clinical practice in a national Chinese sample.

METHODS

A total of 12 medical teaching hospitals participated in CRACE. Data collection began in 2001 and continued until 2004, 1301 patients with ACS were enrolled into the study. We compared the clinical demographics, different therapies and outcomes in hospitals between female and male patients with ACS.

RESULTS

Patients had an average age of 63.13 years (ranging from 27 to 93 years) and 318 female and 983 male subjects were enrolled. Female subjects were older than male patients (67.23 years vs 61.80 years, P < 0.0001). The incidence of angina, heart failure, diabetes mellitus and hypertension in the female group was higher than in male group (73.6% vs 62.3%, P < 0.0001; 8.2% vs 5.7%, P = 0.031; 30.8% vs 18.6%, P < 0.0001 and 66.4% vs 56.8%, P = 0.001 respectively), but the incidence of smoking was less in the female group than in the male group (6.6% vs 66.2%, P < 0.0001). More male patients presented with ST-segment elevation myocardial infarction (STEMI) compared with female patients (48.5% vs 39%, P = 0.002). With the exception of beta-blocker administration, no differences were found among medications including aspirin, ACEI, lipid lowering agents and low-molecular-weight heparin (LMWH) between female and male patients presenting with ACS in hospitals. Compared with male patients with non-ST-segment elevation (NSTE) ACS, female subjects were more prone to receive beta-blockers (75.1% vs 63.4%, P = 0.001). Among STEMI and NSTE-ACS patients, fewer female subjects received reperfusion therapy compared with male subjects (37.1% vs 26.8%, P = 0.013 for STEMI; 53.6% vs 37.2 %, P < 0.0001 for NSTE-ACS). Recurrent angina was more often seen in the female group of patients with the whole spectrum of ACS (25% vs 14.5%, P = 0.005 for STEMI; 29.4% vs 20.2%, P = 0.001 for NSTE-ACS) as was true for patients with congestive heart failure. There was no significant difference in in-hospital death rates between the two groups with ACS (5.6% vs 7.1%, P = 0.2 for STEMI, and 2.1% vs 1.4%, P = 0.738 for NSTE-ACS).

CONCLUSIONS

Female patients with ACS were older than male subjects and thus more often had concomitant diseases but less often had a history of smoking. They less often received reperfusion therapies and more often had higher in-hospital recurrent angina. However, there was no significant difference in in-hospital mortality between the female and male patients.

Investigation of recombinant Schistosoma japonicum paramyosin fragments for immunogenicity and vaccine efficacy in mice

Schistosoma japonicum paramyosin, a 97 kDa myofibrillar protein, is a recognized vaccine candidate against schistosomiasis. To improve its expression and to identify protective epitopic regions on paramyosin, the published Chinese Schistosoma japonicum paramyosin cDNA sequence was redesigned using Pichia codon usage and divided into four overlapping fragments (fragments 1, 2, 3, 4) of 747, 651, 669 and 678 bp, respectively. These gene fragments were synthesized and expressed in Pichia pastoris (fragments 2 and 3) or E. coli (fragments 1 and 4). The recombinant proteins were produced at high level and purified using a two-step process involving Ni-NTA affinity chromatography and gel filtration. BALB/c mice were immunized subcutaneously three times at 2-week-intervals with the purified proteins formulated in adjuvant Quil A. The protein fragments were highly immunogenic, inducing high, though variable, ELISA antibody titres, and each was shown to resemble native paramyosin in terms of its recognition by the anti-fragment antibodies in Western blotting. The immunized mice were subjected to cercarial challenge 2 weeks after the final injection and promising protective efficacy in terms of significant reductions in worm burdens, worm-pair numbers and liver eggs in the vaccinated mice resulted. There was no apparent correlation between the antibody titres generated and protective efficacy, as all fragments produced effective but similar levels of protection.

[Induced expression of the variable region of AMA-1 from Plasmodium falciparum]

OBJECTIVE

To express the variable region of AMA-1 gene from Plasmodium falciparum in Escherichia coli.

METHODS

Genomic DNA of FCC1/HN was used as template and the variable region of AMA-1 gene was amplified by polymerase chain reaction(PCR). The PCR products were digested by endonuclease BamH I and Hind III, cloned into pBlu2KSP. The nucleotide sequences of the variable region of AMA-1 gene were determined by sequencing. The AMA-1 gene fragment was subcloned into plasmid pQE, expressed in E. coli and induced by IPTG. The fusion product as identified by SDS-PAGE gel electrophoresis and Western blotting were proceeded with anti-AMA-1 sera from rabbit.

RESULTS

The size of the variable region of AMA-1 gene from FCC1/HN was 506 bp and encoded 168 amino acids. On SDS-PAGE gel dyed with Coomassie brilliant blue R250, no specific protein band can be discerned, but Western blotting proceeded with anti-AMA-1 sera from rabbit demonstrated that the specific protein band was about 23.0 kDa.

CONCLUSION

The variable region of AMA-1 gene from FCC1/HN was able to be expressed in E. coli and analysis of Western blotting demonstrated that the AMA-1 fussion protein contained specific antigenic epitopes.

[Inducible expression of MSP1 gene of Plasmodium falciparum by a tetracycline-controlled promoter]

OBJECTIVE

To express the entire MSP1 gene of Plasmodium falciparum and its C-terminal 42 kDa fragment using a tetracycline-controlled PLtetO-1 promoter.

METHODS

The entire MSP1 gene and 42 kDa fragment gene were cloned into the plasmid of pZE11, and transformed into E. coli DH5 alpha Z1. Restriction enzyme analysis, SDS-PAGE and Western blotting were used to examine two recombinant plasmids and their expression in E. coli DH5 alpha Z1.

RESULTS

The recombinant plasmids of pZE11/MSP1 and pZE11/MSP1-42 were constructed successfully. The expressive products about 190 kDa and 42 kDa of two genes in E. coli DH5 alpha Z1 were identified by SDS-PAGE and Western blotting.

CONCLUSION

Tightly controlling expression of the MSP1 gene in E. coli is essential to reduce the toxicity of the product to its host cells as well as to provide a feasibility to construct Salmonella vaccine strain which can inducibly express the important malarial vaccine candidate gene.

[Specific antibodies against recombinant MSP1 of Plasmodium falciparum strongly inhibit the parasite growth in vitro]

In order to produce large amounts of protein for vaccine trials, a synthetic msp1-42 gene was inserted into Pichia pastoris expression vector and the plasmid was introduced into Pichia pastoris SMD1168 by electroporation. The expressed MSP1-42 was secreted into the protein-free medium. To measure the conformational properties of MSP1-42,16 monoclonal antibodies (11 recognizing conformational epitopes) were allowed to interact with the Pichia-derived MSP1-42, and all antibodies specific for conserved and K1 protype interacted with the protein. Interestingly, three monoclonal antibodies (e.g. 9.8, 13.1 and 7.3), that were shown not to interact with CHO-derived MSP1, could interact with the Pichia-derived MSP1-42. Rabbits were immunized with recombinant MSP1-42 formulated with CFA adjuvant four times. The rabbits were bled on the day 3 after last immunization, and total IgG isolated by protein A column from the immunized rabbits was shown to strongly inhibit the parasite growth in vitro dose-dependently, whereas IgG from rabbit with adjuvant had no inhibition.

[Expression of chimeric protein of Plasmodium falciparum in yeast recombinant Pichia pastoris in cell-high-density fermentation]

The effects of cultural conditions, which were fermentation period when methanol was as sole carbon source, methanol concentration, range of pH, on the expression of the chimeric protein of Plasmodium falciparum in genetically engineered methylotrophic Pichia pastoris were investigated by shake flask experiments in this paper. The results showed: (1) fermentation period with methanol inducement is about 96 hours; (2) the optimum methanol concentration as sole carbon source is 10 g/L; (3) the range of pH is from 6.0 to 7.0. On the base of above experimental results the cell high-density fermentation had been done on the FMG-5L fermentor with multi-sensors. The results showed that the cell optical density (OD600) can reached 550 and the maximum expression level of target proteins was 780 mg/L which was 4 times higher or more than the shake flask culture's.

[Immunization of mice with plasmid DNA against malaria and regulation of antigen expression by tetracycline-controlled promoter]

Sequence of MSP1-31 of Plasmodium falciparum was constructed into eukaryotic expression vector pTRE, which could be repressed by tetracycline (Tc) and resulted in recombinant plasmid pTRE-31. The plasmid was injected into the quadriceps muscle of BALB/c mice with Tc responsive plasmid pTet-off to measure specific antibodies. The MSP1-31 prokaryotic expressed protein was used as antigen in ELISA. Results showed that mice orally administered by Tc had a seroconversion rate of 7.1% (1/14) 4 weeks after injection, whereas the control mice had a seroconversion rate of 100% and the titers of antibody were raised continusly within 12 weeks. The study suggested that the recombinant plasmids pTRE-31/pTet-off could efficiently induce humoral response against MSP1-31 of malaria. Moreover this immune response was controlled by Tc and was reversible after withdrawal of Tc dilivery. The induction of antibody by removing Tc at the fourth week after injection indicated that DNA vaccine could remain in mice and capable of expressing antigen for at least 4 weeks.

Preliminary study of the distribution of the toxic elements As, Cd, and Hg in human hair and tissues by RNAA

In order to study the relationships between trace element concentrations of hair and internal body burdens, a radiochemical NAA technique has been used for determination of the elements As, Cd, and Hg in autopsy samples of liver, kidney-cortex, lung, and hair from 24 male persons who died by accident. High significant positive correlations were observed between the As concentration in hair and in kidney-cortex, and between Cd and Zn concentrations in kidney-cortex. The contents of Cd, both for lung and kidney-cortex, were related to the smoking habits of the subjects.