大流行流感疫苗血清学检测中马血球和鸡血球血凝抑制试验方法的比较

血凝抑制试验(HI)是评价季节性流感疫苗免疫效果的经典方法。由于对人、禽流感病毒的受体不同,不同来源的红血球检测敏感性可能有差异。实验中比较了经典的鸡血球HI方法和国外报道的马血球HI方法,发现两种方法在检测大流行流感疫苗接种者血清时,于不同毒株抗原检测时表现各不相同,检测结果差异在2倍之内,说明经典的鸡血球HI方法仍适用于评价大流行流感疫苗的免疫效果。     

H7N9灭活疫苗联合MF59佐剂在小鼠体内诱导的长效体液免疫应答

以BALB/c小鼠为模型,探讨H7N9流感病毒灭活疫苗免疫小鼠后所诱导的长效体液免疫应答的动态变化。不同剂量的流感H7N9全病毒灭活疫苗单独或辅以MF59佐剂肌肉注射免疫小鼠一次。连续采集免疫后小鼠15个月的血清,用ELISA方法检测特异性IgG抗体水平,血凝抑制(hemagglutination inhibition,HI)试验和微量中和(microneutralization,MN)试验检测第15个月时的HI抗体和中和抗体效价。实验结果发现,小鼠血清中的特异性IgG抗体水平随时间变化持续缓慢上升,第5个月时达到顶峰,随后略有下降但一直持续平稳状态;IgG抗体滴度与疫苗剂量成正相关,且添加佐剂能提高抗体滴度。HI及MN抗体检测表明,免疫后第15个月产生的抗体能有效中和病毒,且抗体跟疫苗剂量成正比。以上研究表明,H7N9流感病毒灭活疫苗免疫小鼠一次诱导产生的特异性抗体能在较长期内保持比较平稳的抗体滴度,为小鼠提供免疫保护;增加抗原剂量和添加MF59佐剂能增加疫苗特异性抗体水平。该研究为H7N9流感疫苗产生的长期保护效应提供了一定的数据积累和参考。     

人乳头瘤病毒6/11型L2片段的高效表达及免疫效果评价

目的:原核表达人乳头瘤病毒(HPV)6型和11型L2 N端融合蛋白,并初步评价其免疫效果。方法:用重叠PCR将HPV6和HPV11次要衣壳蛋白L2基因5'端片段融合,并在大肠杆菌中表达融合蛋白,纯化后与Al(OH)3佐剂配伍肌肉注射免疫BALB/c小鼠,用ELISA检测血清抗体,以基于假病毒的体外中和试验评价中和抗体水平。结果:ELISA结果显示,3种融合蛋白均能产生针对同型别L2蛋白的高滴度特异性Ig G抗体,滴度为1∶10 000~1∶200 000;体外中和试验显示,3种融合蛋白均能诱发中和抗体和交叉中和抗体,针对同型别的滴度最高可达1∶3200,对于高危型能产生一定水平的交叉中和抗体,滴度为1∶50~1∶800。结论:HPV6/11 L2融合蛋白能够诱发较强的体液免疫反应,产生较高的中和抗体及交叉中和抗体,为HPV L2新型预防性疫苗的研究提供了初步的实验基础。     

中国婴儿中脊灰母传抗体水平对两种疫苗免疫效果的影响

为了了解2月龄婴儿中针对脊髓灰质炎病毒的中和抗体水平,并探讨母传抗体对脊髓灰质炎减毒活疫苗(OPV)和灭活疫苗(IPV)免疫效果的影响。对416名2月龄婴儿分别接种OPV和IPV,采集免疫前后血清,用微量中和法检测血清中Ⅰ、Ⅱ、Ⅲ型脊髓灰质炎病毒中和抗体滴度,评价抗体GMT水平及4倍增长情况。检测结果显示,2月龄婴儿母传抗体Ⅰ、Ⅱ、Ⅲ型阳性率分别为45%、38.2%和17.5%,抗体GMT水平为9.0、8.1和5.2。经接种两组疫苗后,母传抗体阳性者与阴性者免后抗体GMT水平相比,OPV组无明显差异,IPV组阳性者略低于阴性者。在免前抗体滴度<1∶32人群中,OPV组免后抗体滴度4倍增长率及几何滴度增长倍数分别为:Ⅰ型93.6%、71.2;Ⅱ型98.2%、43.7;Ⅲ型91.7%、47.9;IPV组免后抗体滴度4倍增长率及几何滴度增长倍数分别为:Ⅰ型82%、9.4;Ⅱ型62.8%、5.1;Ⅲ型95.6%、11.7;在免前抗体滴度1∶32～1∶128人群中,OPV组Ⅰ型92.3%、23;Ⅱ型86.4%、13.9;Ⅲ型55.6%、4.1;IPV组Ⅰ型48%、2.5;Ⅱ型15%、0.9;Ⅲ型55.6%、2.7。目前中国2月龄婴儿免前脊灰抗体阳性率较高,尤其是Ⅰ、Ⅱ型。脊灰母传抗体对两种疫苗免疫效果有一定干扰,对IPV疫苗的影响较为明显。     

HPV16/18假病毒中和抗体检测方法的验证

目的应用假病毒中和法建立检测血清HPV16/18中和抗体滴度检测方法并进行验证。方法分别采用不同批次假病毒以及不同代次细胞对不同滴度的HPV16/18阳性血清进行多次平行检测,考察这些因素对检验结果的影响;同时通过对抗HPV16/18双价阳性血清、抗HPV16单价阳性血清和抗HPV18单价阳性血清的检测进一步评估中和抗体检测法的准确性、特异性及重复性。结果不同批次假病毒和不同代次细胞对检验结果的影响均在4倍范围内,此外该检测法的准确性、特异性、重复性均在可接受标准范围之内。结论建立的假病毒法可满足中和抗体效价检测的要求,可用于评价疫苗的免疫效果。     

2002~2004年兰州市流感疫苗免疫效果分析

2002~2004年每年9~11月在兰州市对我省使用流感疫苗进行血清学考核,3年用血凝抑制试验(H I)分别检测44、52、49人疫苗免疫前后不同4种血清型流感病毒的抗体水平。结果显示,接种疫苗者30~35 d后流感病毒4个血清型流感病毒H I抗体均有不同程度的增长,H1N1、H3N2、B(Yam agata)、B(V ictorian)保护率(≥1∶40)分别为91.72%、91.72%、81.63%和59.38%;免疫后人体H I抗体滴度的几何均数(GMT)分别为1∶221.76、1∶189.58、1∶71.04和1∶43.04;较接种前H I抗体滴度≥4倍的分别占53.79%(78/145)、58.62%(84/145)、75.51%(37/49)和58.37%(56/96)。血清学检测表明流感疫苗免疫效果好,免疫成功率高。     

用细胞培养的流行性乙型脑炎病毒抗原做ELISA检测特异的IgG抗体

用C6/36细胞增殖流行性乙型脑炎(乙脑)病毒制备抗原,用ELISA法检测乙脑IgG抗体,可获得满意结果。用此法检测了河南,海南地区不同年龄人群的253份血清标本,阳性检出率为55.6％(141/253)。与血凝抑制法(HI)相比较,HI的阳性率仅37.1％(93/253)。两种方法的抗体滴度呈正相关r=0.88。用ELISA检测,乙脑抗体与登革病毒抗原有一定交叉,但滴度平均有16倍差异。本方法重复性良好,具有特异、敏感、简便的特点。可用于乙脑的诊断、流行病学调查和疫苗效果的考核。     

中和试验和ELISA法检测育龄妇女血清麻疹抗体的比较

目的:研究中和试验和ELISA两种麻疹抗体检测方法结果的相关性,并初步探讨新生儿对麻疹易感的原因.方法:采集本院住院的85例小于9月龄麻疹患儿母亲血清,同时采集13位幼年患过麻疹的育龄妇女血清作为对照.通过细胞培养测定血清中和抗体滴度,同时使用ELISA诊断试剂定量检测麻疹IgG抗体,统计学分析比较两种检测结果的相关性.结果:98例血清ELISA法和中和试验法两者均阳性89例,总符合率为90.82%,两者结果不符合主要见于抗体浓度较低的标本;两种检测方法麻疹抗体检测结果具有正相关性(R=0.8285,P＜0.001).当中和抗体滴度大于1:16时,ELISA抗体浓度均高于200 mIU/ml;而当ELISA抗体浓度均高于700 mIU/ml,中和抗体均阳性.患儿患病时,其母亲麻疹ELISA抗体平均水平633 mIU/ml,平均中和抗体滴度1:37,而幼年有麻疹史的同龄妇女麻疹ELISA抗体平均水平为1498 mIU/ml,中和抗体滴度为1:182;两组差异有统计学意义(P＜0.05).结论:中和试验和ELISA麻疹抗体检测结果具有良好的相关性;ELISA麻疹抗体浓度高于700mIU/ml是麻疹中和抗体阳性的可靠指标.婴幼儿麻疹易感性增加与其母亲麻疹抗体低下有关.     

柯萨奇病毒A组16型灭活抗原对小鼠免疫保护作用的研究

为了研究柯萨奇病毒A组16型(Coxsackievirus A16,CVA16)灭活抗原在小鼠体内所产生免疫保护作用效果,我们选用CVA16临床分离株521-01T,在Vero细胞中进行大量培养,并对培养产物进行甲醛灭活及超速离心纯化。SDS-PAGE和Western blot对纯化的灭活病毒纯度及性质进行初步分析。Al(OH)3+CVA16及单独CVA16抗原,分别经皮下注射免疫雌性ICR小鼠;相同免疫途径、剂量于第14和28d加强免疫2次。ELISA法检测CVA16特异性血清IgG抗体滴度;微量中和试验法鉴定血清中和抗体滴度;酶联免疫斑点试验(ELISPOT)检测特异性T淋巴细胞的活化。对Al(OH)3+CVA16抗原免疫组母鼠所产仔鼠进行脑腔攻毒,检测母传抗体对新生乳鼠的保护作用。结果显示,Al(OH)3+CVA16灭活抗原在小鼠体内能诱生高滴度的特异性抗体,3次免疫后产生的特异性血清IgG抗体滴度最高可达1∶1×105(P=0.000),中和滴度高于1∶256。同时,该抗原还可以诱导特异性T淋巴细胞的活化。以1 000LD50的病毒量脑腔接种48h内新生乳鼠的病毒攻击实验显示,该母传抗体对新生乳鼠具有100%的保护。这一结果表明该灭活CVA16病毒抗原具有较好的免疫原性及保护性,为CVA16灭活疫苗的研究及评价体系提供了参考。     

猴血SV40抗体和SV40 DNA携带关系分析

目的　检测 5 7份恒河猴血清及对应的猴血中抗SV4 0抗体、SV4 0DNA的携带情况 ,找出抗体滴度与DNA携带的相关关系。方法　用间接免疫荧光法检测猴血中SV4 0中和抗体 ,聚合酶链反应 (PCR)法检测SV4 0st抗原DNA的携带情况。结果　 5 7份猴血清中 ,SV4 0抗体阳性率为 93% (5 3 5 7) ,抗体滴度最高为 1∶12 80 ,最低为 1∶10 ,GMT为 15 9.5 6 ,PCR检测猴血淋巴细胞SV4 0DNA阳性率为 2 4 .5 6 % (14 5 7) ,当抗体为 1 80以下时 ,病毒整合于血细胞 ,1∶80以上时 ,对st抗原基因的整合有抑制作用。结论　恒河猴SV4 0DNA的携带情况与抗体阳性和滴度呈反相关     

Seroprevalence of pandemic H1N1 antibody among health care workers in Hong Kong following receipt of monovalent 2009 H1N1 influenza vaccine

Background

Healthcare workers in many countries are recommended to receive influenza vaccine to protect themselves as well as patients. A monovalent H1N1 vaccine became available in Hong Kong in December 2009 and around 10% of local healthcare workers had received the vaccine by February 2010.

Methods

We conducted a cross-sectional study of the prevalence of antibody to pandemic (H1N1) 2009 among HCWs in Hong Kong in February–March 2010 following the first pandemic wave and the pH1N1 vaccination campaign. In this study we focus on the subset of healthcare workers who reported receipt of non-adjuvanted monovalent 2009 H1N1 vaccine (Panenza, Sanofi Pasteur). Sera collected from HCWs were tested for antibody against the pH1N1 virus by hemagglutination inhibition (HI) and viral neutralization (VN) assays.

Results

We enrolled 703 HCWs. Among 104 HCWs who reported receipt of pH1N1 vaccine, 54% (95% confidence interval (CI): 44%–63%) had antibody titer ≥1∶40 by HI and 42% (95% CI: 33%–52%) had antibody titer ≥1∶40 by VN. The proportion of HCWs with antibody titer ≥1∶40 by HI and VN significantly decreased with age, and the proportion with antibody titer ≥1∶40 by VN was marginally significantly lower among HCWs who reported prior receipt of 2007–08 seasonal influenza vaccine (odds ratio: 0.43; 95% CI: 0.19–1.00). After adjustment for age, the effect of prior seasonal vaccine receipt was not statistically significant.

Conclusions

Our findings suggest that monovalent H1N1 vaccine may have had suboptimal immunogenicity in HCWs in Hong Kong. Larger studies are required to confirm whether influenza vaccine maintains high efficacy and effectiveness in HCWs.     

Protection of mice and poultry from lethal H5N1 avian influenza virus through adenovirus-based immunization

The recent emergence of highly pathogenic avian influenza virus (HPAI) strains in poultry and their subsequent transmission to humans in Southeast Asia have raised concerns about the potential pandemic spread of lethal disease. In this paper we describe the development and testing of an adenovirus-based influenza A virus vaccine directed against the hemagglutinin (HA) protein of the A/Vietnam/1203/2004 (H5N1) (VN/1203/04) strain isolated during the lethal human outbreak in Vietnam from 2003 to 2005. We expressed different portions of HA from a recombinant replication-incompetent adenoviral vector, achieving vaccine production within 36 days of acquiring the virus sequence. BALB/c mice were immunized with a prime-boost vaccine and exposed to a lethal intranasal dose of VN/1203/04 H5N1 virus 70 days later. Vaccination induced both HA-specific antibodies and cellular immunity likely to provide heterotypic immunity. Mice vaccinated with full-length HA were fully protected from challenge with VN/1203/04. We next evaluated the efficacy of adenovirus-based vaccination in domestic chickens, given the critical role of fowl species in the spread of HPAI worldwide. A single subcutaneous immunization completely protected chickens from an intranasal challenge 21 days later with VN/1203/04, which proved lethal to all control-vaccinated chickens within 2 days. These data indicate that the rapid production and subsequent administration of recombinant adenovirus-based vaccines to both birds and high-risk individuals in the face of an outbreak may serve to control the pandemic spread of lethal avian influenza.     

Influenza H5 hemagglutinin DNA primes the antibody response elicited by the live attenuated influenza A/Vietnam/1203/2004 vaccine in ferrets

Priming immunization plays a key role in protecting individuals or populations to influenza viruses that are novel to humans. To identify the most promising vaccine priming strategy, we have evaluated different prime-boost regimens using inactivated, DNA and live attenuated vaccines in ferrets. Live attenuated influenza A/Vietnam/1203/2004 (H5N1) candidate vaccine (LAIV, VN04 ca) primed ferrets efficiently while inactivated H5N1 vaccine could not prime the immune response in seronegative ferrets unless an adjuvant was used. However, the H5 HA DNA vaccine alone was as successful as an adjuvanted inactivated VN04 vaccine in priming the immune response to VN04 ca virus. The serum antibody titers of ferrets primed with H5 HA DNA followed by intranasal vaccination of VN04 ca virus were comparable to that induced by two doses of VN04 ca virus. Both LAIV-LAIV and DNA-LAIV vaccine regimens could induce antibody responses that cross-neutralized antigenically distinct H5N1 virus isolates including A/HongKong/213/2003 (HK03) and prevented nasal infection of HK03 vaccine virus. Thus, H5 HA DNA vaccination may offer an alternative option for pandemic preparedness.     

Preliminary study about sublingual administration of bacteria-expressed pandemic H1N1 influenza vaccine in miniature pigs

Sublingual (SL) administration of influenza vaccine would be non-invasive and effective way to give human populations protective immunity against the virus, especially when pandemic influenza outbreaks. In this study, the efficacy of pandemic influenza virus-based subunit vaccines was tested after sublingual (SL) adjuvant administration in pigs. Eight specific pathogen-free Yucatan pigs were divided into 4 groups: nonvaccinated but challenged (A) and vaccinated and challenged (B, C, and D). The vaccinated groups were subdivided by vaccine type and inoculation route: SL subunit vaccine (hemagglutinin antigen 1 [HA1] + wild-type cholera toxin [wtCT], B); IM subunit vaccine (HA1 + aluminum hydroxide, C); and IM inactivated vaccine (+ aluminum hydroxide, D). The vaccines were administered twice at a 2-week interval. All pigs were challenged with pandemic influenza virus (A/swine/GCVP-KS01/2009 [H1N1]) and monitored for clinical signs, serology, viral shedding, and histopathology. After vaccination, hemagglutination inhibition titre was higher in group D (320) than in the other vaccinated groups (40–80) at the time of challenge. The mobility and feed intake were reduced in group C. Both viral shedding and histopathological lesions were reduced in groups B and D. Although this study has limitation due to the limited number of pigs (2 pigs per a group), the preliminary data in this study provided the protective potential of SL administration of bacteria-expressed pandemic H1N1 influenza vaccine in pigs. There should be additional animal studies about effective adjuvant system and vaccine types for the use of SL influenza vaccination.     

Cross‐reactive antibody response to the pandemic A (H1N1) 2009 influenza virus induced by vaccination with a seasonal trivalent influenza vaccine: a longitudinal study of three influenza seasons in Japan

The cross‐reactivity of antibody to the swine‐origin pandemic influenza A (H1N1) 2009 virus induced by vaccination with a seasonal trivalent influenza vaccine was studied. Paired sera from a cohort of adult volunteers vaccinated with a trivalent seasonal influenza vaccine every year from 2006 to 2008 were collected each year and tested by hemagglutination inhibition (HI) for antibody against the pandemic influenza A (H1N1) 2009 virus. There was little increase in the geometric mean titer overall; a slight increase was detected in the sera obtained in the 2007–2008 season but not in the other two seasons. The proportion of individuals with HI antibody titers ≥ 1:40 did not change significantly from year to year. These results indicate that cross‐reactivity of the antibodies induced by a trivalent seasonal vaccine to the pandemic influenza A (H1N1) 2009 virus is marginal.     

Virus-Like Particle Vaccine Protects against 2009 H1N1 Pandemic Influenza Virus in Mice

Background

The 2009 influenza pandemic and shortages in vaccine supplies worldwide underscore the need for new approaches to develop more effective vaccines.

Methodology/Principal Findings

We generated influenza virus-like particles (VLPs) containing proteins derived from the A/California/04/2009 virus, and tested their efficacy as a vaccine in mice. A single intramuscular vaccination with VLPs provided complete protection against lethal challenge with the A/California/04/2009 virus and partial protection against A/PR/8/1934 virus, an antigenically distant human isolate. VLP vaccination induced predominant IgG2a antibody responses, high hemagglutination inhibition (HAI) titers, and recall IgG and IgA antibody responses. HAI titers after VLP vaccination were equivalent to those observed after live virus infection. VLP immune sera also showed HAI responses against diverse geographic pandemic isolates. Notably, a low dose of VLPs could provide protection against lethal infection.

Conclusion/Significance

This study demonstrates that VLP vaccination provides highly effective protection against the 2009 pandemic influenza virus. The results indicate that VLPs can be developed into an effective vaccine, which can be rapidly produced and avoid the need to isolate high growth reassortants for egg-based production.     

Screening of a high growth influenza B virus strain in Vero cells

Due to the insufficient supply of embryonated chicken eggs, the preparation of large quantities of inactivated influenza vaccines will require an alternative virus culture system after the emergence or reemergence of a pandemic influenza virus. The Vero cell is one of the ideal options since it was used for producing many kinds of human vaccines. However, most of the influenza viruses can not grow well in Vero cells. To develop a new influenza vaccine with Vero cells as a substrate, the virus needs to adapt to this cell substrate to maintain high growth characteristics. By serial passages in Vero cells, the B/Yunnan/2/2005va (B) strain was successfully adapted to Vero cells, with the hemagglutination titer (HAT) of the virus reaching 1:512. The high growth characteristic of this strain is stable up to 21 passages. The strain was identified by hemagglutination inhibition (HAI) test and sequencing respectively; the HA₁ gene sequence of the virus was cloned and analyzed. The screening and establishment of high growth B virus provides an important tool for influenza vaccine production in Vero cells.     

Efficacy of seasonal pandemic influenza hemagglutinin DNA vaccines delivered by electroporation against aseasonal H1N1 virus challenge in mice

Prophylactic DNA vaccines against the influenza virus are promising alternatives to conventional vaccines. In this study, we generated two candidate gene-based influenza vaccines encoding either the seasonal or pandemic hemagglutinin antigen (HA) from the strains A/New Caledonia/20/99 (H1N1) (pV1A5) and A/California/04/2009 (H1N1) (pVEH1), respectively. After verifying antigen expression, the immunogenicity of the vaccines delivered intramuscularly with electroporation was tested in a mouse model. Sera of immunized animals were tested in hemagglutination inhibition assays and by ELISA for the presence of HA-specific antibodies. HA-specific T-cells were also measured in IFN-γ ELISpot assays. The protective efficacy of the candidate influenza vaccines was evaluated by measuring mortality rates and body weight after a challenge with 100 LD(50) of mouse-adapted A/New Caledonia/20/99 (H1N1). Mice immunized with either one of the two vaccines showed significantly higher T cell and humoral immune responses (P<0.05) than the pVAX1 control group. Additionally, the pV1A5 vaccine effectively protected the mice against a lethal homologous mouse-adapted virus challenge with a survival rate of 100% compared with a 40% survival rate in the pVEH1 vaccinated group (P<0.05). Our study indicates that the seasonal influenza DNA vaccine completely protects against the homologous A/New Caledonia/20/99 virus (H1N1), while the pandemic influenza DNA vaccine only partially protects against this virus.     

Detection and Characterization of Clade 1 Reassortant H5N1 Viruses Isolated from Human Cases in Vietnam during 2013

Highly pathogenic avian influenza (HPAI) H5N1 is endemic in Vietnamese poultry and has caused sporadic human infection in Vietnam since 2003. Human infections with HPAI H5N1 are of concern due to a high mortality rate and the potential for the emergence of pandemic viruses with sustained human-to-human transmission. Viruses isolated from humans in southern Vietnam have been classified as clade 1 with a single genome constellation (VN3) since their earliest detection in 2003. This is consistent with detection of this clade/genotype in poultry viruses endemic to the Mekong River Delta and surrounding regions. Comparison of H5N1 viruses detected in humans from southern Vietnamese provinces during 2012 and 2013 revealed the emergence of a 2013 reassortant virus with clade 1.1.2 hemagglutinin (HA) and neuraminidase (NA) surface protein genes but internal genes derived from clade 2.3.2.1a viruses (A/Hubei/1/2010-like; VN12). Closer analysis revealed mutations in multiple genes of this novel genotype (referred to as VN49) previously associated with increased virulence in animal models and other markers of adaptation to mammalian hosts. Despite the changes identified between the 2012 and 2013 genotypes analyzed, their virulence in a ferret model was similar. Antigenically, the 2013 viruses were less cross-reactive with ferret antiserum produced to the clade 1 progenitor virus, A/Vietnam/1203/2004, but reacted with antiserum produced against a new clade 1.1.2 WHO candidate vaccine virus (A/Cambodia/W0526301/2012) with comparable hemagglutination inhibition titers as the homologous antigen. Together, these results indicate changes to both surface and internal protein genes of H5N1 viruses circulating in southern Vietnam compared to 2012 and earlier viruses.     

Efficacy of vaccination with different combinations of MF59-adjuvanted and nonadjuvanted seasonal and pandemic influenza vaccines against pandemic H1N1 (2009) influenza virus infection in ferrets

Serum antibodies induced by seasonal influenza or seasonal influenza vaccination exhibit limited or no cross-reactivity against the 2009 pandemic swine-origin influenza virus of the H1N1 subtype (pH1N1). Ferrets immunized once or twice with MF59-adjuvanted seasonal influenza vaccine exhibited significantly reduced lung virus titers but no substantial clinical protection against pH1N1-associated disease. However, priming with MF59-adjuvanted seasonal influenza vaccine significantly increased the efficacy of a pandemic MF59-adjuvanted influenza vaccine against pH1N1 challenge. Elucidating the mechanism involved in this priming principle will contribute to our understanding of vaccine- and infection-induced correlates of protection. Furthermore, a practical consequence of these findings is that during an emerging pandemic, the implementation of a priming strategy with an available adjuvanted seasonal vaccine to precede the eventual pandemic vaccination campaign may be useful and life-saving.