Both hemagglutination inhibition(HI) and virus neutralization(VN) methods for determining the antibody titer were applied to evaluate the immunological efficacy of pandemic influenza vaccine and the results of two methods were compared.Cytopathic effect(CPE) observation and red blood hemagglutination(HA) were used to record VN endpoints and achieved similar results.Two kinds of detection methods showed excellent agreement in this study,with correlation factor of 0.85.Thus both methods can be used to evaluate the immunological efficacy of pandemic influenza vaccine.

Background Emergence of severe acute respiratory syndrome (SARS) from the winter of 2002 to the spring of 2003 has caused a serious threat to public health. Methods To evaluate the safety and immunogenicity of the inactivated SARS coronavirus (SARS-CoV) vaccine, 36 subjects received two doses of 16 SARS-CoV units (SU) or 32 SU inactivated SARS-CoV vaccine, or placebo control. Results On day 42, the seroconversion reached 100% for both vaccine groups. On day 56, 100% of participants in the group receiving 16 SU and 91.1% in the group receiving 32 SU had seroconverted. The geometric mean titre of neutralizing antibody peaked 2 weeks after the second vaccination, but decreased 4 weeks later. Conclusion The inactivated vaccine was safe and well tolerated and can elicit SARS-CoV-specific neutralizing antibodies.

BACKGROUND:Avian influenza A virus H5N1 has caused widespread infections that have resulted in severe disease or death in poultry and wild birds as well as human beings. This virus has the potential to emerge as a pandemic threat and H5N1 vaccines are being developed in many countries. Our aim was to assess the safety and immunogenicity of an inactivated adjuvanted whole-virion H5N1 vaccine. METHODS:A stratified randomised, placebo-controlled, double-blind phase I clinical trial was done in 120 volunteers aged 18-60 years. Volunteers were assigned to receive two doses of placebo (n=24) or an inactivated whole-virion influenza A (H5N1) vaccine with 1.25 microg (24), 2.5 microg (24), 5 microg (24), or 10 microg (24) haemagglutinin per dose with aluminium hydroxide adjuvant on day 0 and 28. Serum samples were obtained on day 0, 14, 28, 42, and 56 for haemagglutination inhibition and virus neutralisation assays. This trial is registered with the ClinicalTrials.gov registry with the number NCT00356798. FINDINGS:All four formulations of vaccines were well tolerated. No serious adverse event was reported and most local and systemic reactions were mild and transient. All formulations induced antibody responses after the first dose; the highest immune response of 78% seropositivity was seen in the 10 mug group after two vaccine doses. Two individuals dropped out: one in the 1.25 microg group (withdrew consent) and one in the 10 microg group (discontinued); one individual was also excluded from the final analysis. INTERPRETATION:A two-dose regimen of an adjuvanted 10 microg inactivated whole-virion H5N1 vaccine met all European regulatory requirements for annual licensing of seasonal influenza vaccine. Lower doses of this vaccine could achieve immune responses equivalent to those elicited by adjuvanted or non-adjuvanted split-virion vaccines. The use of a whole virion vaccine could be more adaptable to the antigen-sparing strategy recommended by WHO for protection against an influenza pandemic.

A reference antiserum for SARS is in urgent need in the development of SARS vaccine and other serological test of SARS research. Convalescent serum was collected from clinical confirmed patient. ELISA, Western-blotting and neutralization assay detected specific antibody against SARS coronavirus. This antiserum was prepared as in-house reference antiserum, freeze-dried and sealed in ampoules. The potency of this reference antiserum is defined to be 52.7 U after extensive calibration. Further, collaborative studies for the evaluation of this serum are needed in order to satisfy the requirements for international reference antiserum.

A seroepidemiologic study was conducted in North China in 2003 to determine the neutralizing antibody titer of severe acute respiratory syndrome (SARS) convalescent sera. A total of 99 SARS convalescent serum samples were collected from patients from the Inner Mongolia Autonomous Region, Hebei Province, and Beijing 35-180 days after the onset of symptoms. The anti-SARS antibodies were detected by enzyme-linked immunosorbent assay (ELISA), neutralization assay, and Western blot. Eighty-seven serum samples were confirmed to be positive for SARS antibodies. The neutralizing antibody titer of the 87 positive sera was analyzed quantitatively by neutralization assay. The geometric mean titer (GMT) of the 87 convalescent sera was 1:61. The Kolmogorov-Smirnov test showed that the neutralizing antibody titers conform to normal distribution, which suggests that the average anti-SARS antibody level in this study was representative of the convalescent antibody level of the SARS population. This result could be useful for the development and quality control of SARS vaccines.

RNA病毒在复制时有易出错的倾向,因此SARS病毒在传染或传代过程中易发生突变而产生不同的毒株,这种机制也利于病毒逃脱宿主的免疫系统而生存下来.许多研究也表明,不同的SARS病毒分离株的全基因组序列存在不同程度的差异,这些差异的研究无疑对SARS病毒疫苗的研制具有重要的指导意义.同时,对SARS病毒在传代过程中的遗传稳定性及核酸特性的分析,是SARS疫苗研制不可或缺的环节.采用PCR产物直接测序的方法,对2株用Vero细胞培养经过多次传代的SARS病毒进行了全基因组序列的测定,通过比较分析发现该病毒在传代过程中具有高遗传稳定性,其中检定参比株(Sino1株)2和11代全基因组序列比较有4个碱基的变化,而候选疫苗株(Sino3株)3与10代的基因组全序列仅有1个碱基的差异.SARS病毒在Vero细胞上传代的遗传稳定性表明,以此制备的灭活病毒疫苗是稳定的.

SARS coronavirus is an RNA virus whose replication is error-prone, which provides possibility for escape of host defenses, and even leads to evolution of new viral strains during the passage or the transmission. Lots of variations have been detected among different SARS-CoV strains. And a study on these variations is helpful for development of efficient vaccine. Moreover, the test of nucleic acid characterization and genetic stability of SARS-CoV is important in the research of inactivated vaccine. The whole genome sequences of two SARS coronavirus strains after passage in Vero cell culture were determined and were compared with those of early passages, respectively. Results showed that both SARS coronavirus strains have high genetic stability, although nearly 10 generations were passed. Four nucleotide variations were observed between the second passage and the 11th passage of Sino1 strain for identification of SARS inactivated vaccine. Moreover, only one nucleotide was different between the third passage and the 10th passage of Sino3 strain for SARS inactivated vaccine. Therefore, this study suggested it was possible to develop inactivated vaccine against SARS-CoV in the future.