采用蚀斑技术克隆纯化口蹄疫病毒的研究

本研究应用BHK₂₁细胞通过蚀斑试验克隆和再次克隆牛AsiaⅠ型口蹄疫病毒AKT03毒株并对克隆前和第1次、第2次克隆的口蹄疫病毒毒株的细胞半数感染量（TCID₅₀）、乳鼠半数致死量（LD₅₀）进行比较测定,结果表明,通过蚀斑试验成功克隆了牛AsiaⅠ型口蹄疫病毒AKT03毒株,第1次克隆的毒株和第2次克隆的毒株TCID₅₀和LD₅₀效价明显提高。     

Saponin Adjuvants. Vi. The Adjuvant Activity of Quil a in Trivalent Vaccination of Cattle and Guinea Pigs Against Foot-And-Mouth Disease

The saponin adjuvant Quil A was investigated in trivalent vaccination against foot-and-mouth disease with a concentrated vaccine based on BHK suspension cell virus of the serotypes O, A and G. The activity in cattle was estimated on the basis of seroneutra-lizing antibodies. Five and 10 ml doses with or without 1 mg of Quil A were each injected into 6 animals. Seroneutralizing antibodies were estimated at regular intervals during a period of 29 weeks. The activity in guinea pigs was estimated by experimental challenge. One ml doses of serial 4-fold dilutions of the vaccine with or without 50 µg of Quil A were injected into 24 groups of 20 guinea pigs. Challenge was given 3 weeks after vaccination.It was concluded that Quil A showed adjuvant activity in cattle and guinea pigs with all the serotypes used in the trivalent vaccination.     

牛口蹄疫Asia-Ⅰ型灭活疫苗LPB-E抗体滴度与免疫保护相关性研究

抽取7批牛口蹄疫Asia—Ⅰ型灭活疫苗，用OIE推荐的50％保护（PD50）试验方法进行免疫保护试验；同时，用OIE推荐的液相阻断酶联免疫吸附试验（LPB—E）检验程序测定了7批疫苗免疫保护试验的103头牛的血清抗体滴度。经过对获得数据的统计和处理分析证明，LPB—E抗体滴度与牛免疫保护率存在着显著的正相关性（P〈0．05），相关系数为0．91，概率分析表明，LPB—E抗体滴度≥2．1（1：126）时，95％的免疫牛能够抵抗与疫苗毒株同源的10^4ID50强毒的攻击。     

口蹄疫病毒重组鸡痘病毒活载体疫苗和DNA疫苗免疫牛的试验研究

将本课题组构建的共表达FMDV衣壳蛋白前体P1—2A基因以及蛋白酶3C基因的重组鸡痘病毒活载体疫苗vUTAL3CP1以及共表达P1—2A和猪白介索18基因的重组DNA疫苗（pVIRIL18P1），分别以单独及混合的共3种方式接种牛，然后通过间接ELISA、中和试验和T淋巴细胞增殖试验评价其诱导的特异性体液和细胞免疫水平。结果表明这2种基因工程疫苗均能诱导牛产生特异性的体液及细胞免疫应答。其中重组鸡痘病毒vUTAL3CP1免疫组以及联合免疫组（vUTAL3CP1／pVIRIL18P1，pVIRIL18P1／vUTAL3CP1）诱导的中和抗体滴度分别达到1：64、1：64和1：54，已接近于常规灭活疫苗水平（1：90），而特异性的T淋巴细胞增殖反应则比后者高得多（P〈0．01）。该研究结果为进一步进行免疫攻毒试验，并最终筛选出最佳疫苗和免疫程序奠定了基础。     

口蹄疫疫苗的悬浮培养工艺研究

通过生物反应器中进行BHK21细胞悬浮培养并逐级放大,分别接种口蹄疫OJMS/2000株与Asia 1/JSL株,纯化灭活后制备50批疫苗,结果均符合《口蹄疫O型、亚洲Ⅰ型二价疫苗(OJMS株+ JSL株)制造及检验规程》（以下称规程）所规定的各项标准,病毒146S抗原含量比转瓶培养提高10倍以上、疫苗的不良反应得到进一步改善.     

猪瘟、猪口蹄疫、高致病性猪蓝耳病疫苗不同组合免疫效果观察

选择未免疫高致病性猪蓝耳病、O型口蹄疫和猪瘟疫苗的30～40日龄仔猪273头,随机分成5组,按5种免疫程序进行猪瘟、O型口蹄疫和高致病性猪蓝耳病免疫工作,并进行免疫副反应和免疫效果评估。试验结果表明：按照C组免疫程序节省时间,免疫效果好,免疫副反应率低。     

Quantification of water buffalo (Bubalus bubalis) cytokine expression in response to inactivated foot-and-mouth disease (FMD) vaccine

This study describes the quantification of cytokine expression of vaccinated water buffaloes with FMD inactivated vaccine. Using real-time PCR quantification assay, expression of Th1 (IL-2, IL-12p40, IFNγ); Th2 (IL-4, IL-10) and inflammatory (IL-6, TNFα) cytokines were quantified weekly for the entire three-week duration of the experiment. It was noted that IFNγ, IL-10 and TNFα had peaked on week three post-vaccination while the remaining cytokines peaked on the second week and decreased by the third week. The counteraction between IFNγ and IL-4 was noted as well as the possible suppressive action of IL-10 to that of IL-2 and IL-12, which is a common phenomenon between Th1 and Th2 cytokines. Synergy between TNFa and IL-6 was also observed. These findings suggest that within the immune system of water buffalo there is a dynamic cell-mediated and humoral interaction in response to immunogen. This assessment of the cytokine expressions is vital for the study of water buffalo disease progression and concurring protective immune responses.     

Risk factors for foot and mouth disease seroprevalence in indigenous cattle in Southern Ethiopia: the effect of production system

A serological survey to investigate risk factors for Foot and Mouth Disease (FMD) occurrence was conducted between October 2007 and March 2008 in Southern Ethiopia. Antibodies against non-structural protein of FMD virus (using 3abc ELISA) were measured as indicator of exposure to the virus. The seroprevalence of FMD was 9.5% (95%CI = 7.7 – 11.3, n = 1020) and 48.1% (95% CI = 36.8 – 59.4%, n = 79), respectively at animal and herd levels. Within herd seropositivity was ranged from 6.7 to 46.7% with 18.6% (95%CI = 14.6 – 22.5%) risk of being seropositive for an animal in positive herds. The most important herd level risk factors identified were pastoral system (OR = 16.3, 95% CI = 2.0 -133.7) compared to sedentary, low altitude (OR = 7.5, 95% CI 1.4 -40.7) compared to high altitude, keeping cattle with small ruminants (OR = 5.1, 95% CI 1.0 -25.2) when compared to one species or alone. Seroprevalence was significantly higher (P <0.05) in South Omo than Sidama and Gamo Gofa areas. The odds of seropositivity were 2.8 and 2.3 times higher in the adult (>4 years) and maturing animals (3–4 years) compared to young age category (<3 years). Both multivariable logistic and negative binomial regressions depicted that production system was the major risk factor for FMD seropositivity. Consequently, higher prevalence of FMD in pastoral system where animals are an integral part of life has substantial livelihood and economic implications, which signifies the need for devising control measures.     

口蹄疫免疫与疫苗关系研究进展

免疫是预防口蹄疫的重要理论基础,研究动物机体针对口蹄疫的免疫机理,寻求预防口蹄疫的技术途径,为疫苗研制提供技术支撑。本文主要研究口蹄疫的体液免疫,细胞免疫以及细胞因子在预防口蹄疫方面的重要机理,以及各种口蹄疫疫苗在免疫学方面的优缺点,以便为最大程度的利用其免疫优势,为口蹄疫新苗的设计和防控提供理论依据。     

2017—2019年广西玉林市牛羊口蹄疫和小反刍兽疫血清抗体检测

为了解广西玉林市牛羊口蹄疫(FMD)和小反刍兽疫(PPR)免疫情况,2017—2019年采用酶联免疫吸附试验(ELISA),对从玉林市7个县(市、区)234个种畜场、规模养殖场和散养户采集2244份羊血清和922份牛血清样本进行O型、A型和亚洲I型FMD以及PPR免疫抗体检测,并比较不同年份、不同地区的免疫抗体水平。结果显示:2017—2019年,玉林市牛羊O型FMD抗体场群及个体合格率基本保持在70%以上,但部分地区的抗体合格率较低(P<0.05);亚洲I型FMD抗体合格率2017年偏低,但2018年后直线上升至80%以上;A型FMD抗体合格率普遍较低,均不足70%。PPR免疫合格率逐年增长,均保持在70%以上,且无显著地区差异(P>0.05)。结果表明,广西玉林市牛羊O型、亚洲I型FMD和羊PPR的整体免疫效果较好,但A型FMD免疫效果较差,且FMD免疫效果存在一定的地区不均衡性。因此,玉林市应根据各地区实际情况,持续加强FMD、PPR免疫和监测,确保各地区牛羊处于较高的免疫保护水平。本调查为玉林市有效防控此类疫病提供了技术支持。