Persistence of immune responses to vaccine against haemorrhagic fever with renal syndrome in healthy adults aged 16-60 years: results from an open-label2-year follow-up study.

BACKGROUND: Approximately 2 million doses of vaccine against haemorrhagic fever with renal syndrome (HFRS) have been used annually in China. However, there were limited studies focused on persistence of immune responses to HFRS vaccine in healthy adults. A phase 4, multicentre, open trial has been undertaken to assess antibody persistence after HFRS vaccination of healthy adolescents and adults aged 16-60 years. METHODS: The vaccine was administered as a three-dose series at 0, 2 weeks and 6 months, including two primary doses and one booster dose. Anti-hantavirus IgG antibodies were measured by enzyme-linked immunosorbent test (ELISA) pre-vaccination and 1.5, 7 and 24 months after the initial vaccination. RESULTS: A total of 143 individuals aged 16-60 years were included. The median OD (range) values of IgG antibody were 0.005 (0.004-0.016), 0.116 (0.036-0.620), 0.320 (0.065-0.848) and 0.128 (0.011-0.649) pre-vaccination and at 1 month after the two primary doses, 1 month after the booster dose and 18 months after the booster dose. The positivity rate was 7.7%, 40.6%, 62.2% and 48.2%, respectively. CONCLUSIONS: The two primary doses could help healthy individuals to generate an immune response, and this three-dose series may be better than a two-dose regimen.

Long-term persistence of anti-hantavirus antibodies in sera of patients undergoing hemorrhagic fever with renal syndrome and subjects vaccinated against the disease.

Background China has the highest prevalence of hemorrhagic fever with renal syndrome (HFRS) and accounts for 90% of the total cases worldwide. However, the long-term persistence of anti-hantavirus antibodies in sera of patients with HFRS and subjects vaccinated against the disease remains unclear. The aim of the present study was to investigate the prevalence of anti-hantavirus IgG antibodies in sera of patients with prior HFRS, versus subjects vaccinated against the disease and controls in Shaanxi, China. Methods Six hundred individuals were included in this study. We quantified anti-hantavirus IgG antibodies in HFRS patients (n = 100), vaccinees (n = 200), controls from endemic regions (n = 200), and controls from non-endemic regions (n = 100) in China. Results The median optical density (OD) values (range) were 0.803 (0.008-1.813), 0.075 (0.004-1.565), 0.026 (0-1.179), and 0.015 (0.009-0.118) for HFRS patients, vaccinated subjects, endemic controls, and non-endemic controls, respectively. There was a strikingly significant difference between the HFRS group and each non-HFRS group (p < 0.001). The vaccinated subjects were also significantly different from the endemic controls. The time since the acute phase was correlated with the OD values of the HFRS patients. Conclusions Our study suggests that HFRS patients gain long-lasting protection and that vaccination may be an effective way to stimulate antibody production.

[Comparison of direct immune-fluorescent assay and real-time quantitative PCR in detecting the Hantavirus].

OBJECTIVE: To compare the differences between the direct immuno-fluorescent assay (DFA) and real-time quantitative PCR in detecting the Hantavirus (HV) in rat lungs. METHODS: From April to October in 2012, a total of 479 rats were caught by mouse-trap in residential or wild areas in Huxian, Jingyang, and Meixian of Shaanxi province, where haemorrhagic fever with renal syndrome (HFRS) was highly prevalent. The rats were dissected to take the two lungs, one was frozen and applied immuno-fluorescent assay to detect HV antigen while the other one was extracted its RNA and detected HV nucleic acid by real-time quantitative PCR. Then we compared the positive rate of the two methods. RESULTS: Out of the 479 rats, 105 were caught from residential areas and the other 374 were caught from wild areas. Among the 105 rats caught from residential areas, no HV were detected out neither by DFA nor by real-time quantitative PCR. Among the 374 wild rats, 13.1% (49/374) were detected HV positive by DFA and 14.7% (55/374) were detected HV positive by real-time quantitative PCR. The difference showed no statistical significance (χ(2) = 0.402, P = 0.526). When detecting each lung sample, the HV positive rate was 10.2% (49/479) under the detection by DFA while the HV positive rate was 11.5% (55/479) under the detection by real-time quantitative PCR. The difference had no statistical significance (χ(2) = 1.286, P = 0.257) and the consistency coefficient was 68.2% under the paired chi-square test analysis, which showed high consistency (u = 11.759, P < 0.05). The sensitivity of real-time quantitative PCR to detect HV was 77.6% (38/49) comparing with DFA as standard, and the specificity was 96.1% (413/430). Out of the 9 suspected HV positive sample detected by DFA, 6 were confirmed positive by real-time quantitative PCR and 3 were denied. CONCLUSION: Compared with the DFA, real-time quantitative PCR could also be used to detect the infection of HV in rats, and the result might be more stable.

[Cloning and expression analysis of Sirt2 in HEK293 cells].

AIM: To construct eukaryotic expression vector of Sirt2 and detect its expression in HEK293 cells. METHODS: Total RNA was isolated from brain tissue of adult SD rat. A 1 130 bp fragment containing the coding region of Sirt2 was amplified by RT-PCR and the resulting PCR product was subcloned into PMD20-T vector and sequenced. Coding region of Sirt2 was generated with PCR by using the PMD20-T-Sirt2 as template, the amplified PCR fragment was inserted into the EcoR I and Hind III sites of the pcDNA3.1myc-his(-)A expression vector, and the sequence was confirmed by DNA sequencing. The expression of new construct pcDNA3.1 myc-his(-)A-Sirt2 in HEK293 cells was detected by immunofluorescence. RESULTS: The full length coding region of Sirt2 was obtained and confirmed by sequencing, the expression of Sirt2 was detected successfully in HEK293 cells. CONCLUSION: The eukaryotic expression vector of Sirt2 has been successfully constructed, which will provide a useful tool for designing an in-depth investigation of the role of Sirt2.