Protective Efficacy of Newcastle Disease Vaccines against Prevalent Strains in Recent Years

[Objective] To investigate the protective efficacy of currently available Newcastle disease vaccines against currently prevalent strains and thus provide guidance for the application of vaccines and the prevention and control of Newcastle disease. E Method] The 6-week-old SPF chickens were respectively inoculated with five live attenuated Newcastle disease vaccines （A, B, C, D, and E） at the dose of 1-fold or 0.01-fold usage via intranasal, intraocular or oral route. After 14 d post immunization, the titers of HI antibody were detected. And all the chickens were chal- lenged by Newcastle disease virus （NDV） FEo standard strain or the isolated wild strains, NDV-2007-HB and NDV-2008-YB. The clinical symptoms of chickens were continuously observed, and the morbidity and mortality were determined. [ Resalt] After 14 d post immunization, antibodies were induced at a protective level in chickens immunized with the five vaccines. As shown by the animal experiment, the five vaccines at the dose of 1-fold or 0.01-fold usage protected all vaccinated chickens from the death caused by NDV strain, and more than 90% of vaccinated chick- ens from the death caused by NDV-2007-HB strain, while the vaccines, A, B, and C, at the dose of 0.01 -fold usage protected more than 90% of vaccinated chickens from the death caused by NDV-2008-YB strain. E Conclusion] Under laboratory conditions, the currently available Newcastle disease vaccines have better protective efficacy against the two currently prevalent NDV strains and prevent the occurrence of Newcastle disease.

A Natural Vaccine Candidate Strain Against Cholera

E1 Tor Vibrio cholerae (EVC) strains may be classifled into two kinds-epidemigenic (EEVC) strains and non-epidemigenic (NEEVC) strains-based on a phage-biotyping system. A large number of EEVC strains have been screened for toxigenic and putative colonization attributes. One such naturally occurring strain (designated IEM 101) has been found which is devoid of genes encoding cholera toxin (CT), accessory cholera enterotoxin (ACE), zonula occludens toxin (ZOT), but possesses RS1 sequences and toxin-coregulated pilus A gene (tcpA) although tcpA is poorly expressed. It expresses type B pili but does not posses type C pili. It is an E1 Tor Ogawa strain and does not cause fluid accumulation in rabbit ileal loop tests. Active immunization of rabbits with strain IEM 101 elicited good protection against challenge with virulent strains of V cholerae O1. Oral administrationcaused no side effects in 15 human volunteers, colonized the gut for four to ten days and elicited good immune responses

Protective efficacy of an H5/H7 trivalent inactivated vaccine(H5-Re13,H5-Re14, and H7-Re4 strains) in chickens, ducks, and geese against newly detected H5N1, H5N6, H5N8, and H7N9 viruses

Some H5 viruses isolated in poultry or wild birds between 2020 and 2021 were found to be antigenically different from the vaccine strains(H5-Re11 and H5-Re12) used in China. In this study, we generated three new recombinant vaccine seed viruses by using reverse genetics and used them for vaccine production. The vaccine strain H5-Re13 contains the hemagglutinin(HA) and neuraminidase(NA) genes of an H5 N6 virus that bears the clade 2.3.4.4 h HA gene, H5-Re14 contains the HA and NA genes of an H5 N8 virus that bears the clade 2.3.4.4 b HA gene, and H7-Re4 contains the HA and NA genes of H7 N9 virus detected in 2021. We evaluated the protective efficacy of the novel H5/H7 trivalent inactivated vaccine in chickens, ducks, and geese. The inactivated vaccine was immunogenic and induced substantial antibody responses in the birds tested. Three weeks after vaccination, chickens were challenged with five different viruses detected in 2020 and 2021: three viruses(an H5 N1 virus, an H5 N6 virus, and an H5 N8 virus) bearing the clade 2.3.4.4 b HA gene, an H5 N6 virus bearing the clade 2.3.4.4 h HA gene, and an H7 N9 virus. All of the control birds shed high titers of virus and died within 4 days post-challenge, whereas the vaccinated chickens were completely protected from these viruses. Similar protective efficacy against H5 viruses bearing the clade 2.3.4.4 h or 2.3.4.4 b HA gene was observed in ducks and geese. Our study indicates that the newly updated H5/H7 vaccine can provide solid protection against the H5 and H7 N9 viruses that are currently circulating in nature.

Protective efficacy of an H5/H7 trivalent inactivated vaccine produced from Re-11, Re-12, and H7-Re2 strains against challenge with different H5 and H7 viruses in chickens

We developed an H5/H7 trivalent inactivated vaccine by using Re-11, Re-12, and H7-Re2 vaccine seed viruses, which were generated by reverse genetics and derived their HA genes from A/duck/Guizhou/S4184/2017(H5N6) (DK/GZ/S4184/17) (a clade 2.3.4.4d virus), A/chicken/Liaoning/SD007/2017(H5N1) (CK/LN/SD007/17) (a clade 2.3.2.1d virus), and A/chicken/ Guangxi/SD098/2017(H7N9) (CK/GX/SD098/17), respectively. The protective efficacy of this novel vaccine and that of the recently used H5/H7 bivalent inactivated vaccine against different H5 and H7N9 viruses was evaluated in chickens. We found that the H5/H7 bivalent vaccine provided solid protection against the H7N9 virus CK/GX/SD098/17, but only 50–60% protection against different H5 viruses. In contrast, the novel H5/H7 trivalent vaccine provided complete protection against the H5 and H7 viruses tested. Our study underscores the importance of timely updating of vaccines for avian influenza control.

The Lapinized Chinese Strain Vaccine Against Classical Swine Fever Virus:A Retrospective Review Spanning Half A Century

Classical swine fever （CSF）, a list A disease of Office International des Epizooties, is caused by classical swine fever virus （CSFV） belonging to the Flaviviridae family. The well-known lapinized Chinese strain of CSFV, also known as C-strain, was developed in China in the mid-1950s. In the past half a century, the vaccine has been proved to be safe and immunogenic in pigs of essentially any age. It is of high efficacy, providing immunized animals with broad-spectrum, sometimes lifelong, protection, which is contributed by both cell-mediated immunity and humoral immunity, against essentially all genotypes or subgenotypes of the virus. The maternal antibodies derived from immunized sows can confer solid protection of their offspring from disease; however, they have been proved to inhibit the successful active immunization of C-strain vaccine. The complete genomes of C-strain and dozens of established or field strains have been sequenced and annotated. Recently, the reverse genetics system of C-strain has been developed, resulting in several C- strain-derived candidate marker vaccines. Many countries manage to control or even eradicate CSF with the aid of mass vaccination with C-strain. in spite of these efforts, the eradication of the disease worldwide remains a big challenge and needs to go a long way, and provably still resorts to genetically modified C-strain vaccine. The authors present an overview of the characteristics of the vaccine, which has stood the test of half a century.

Effect of Attenuated Highly Pathogenic Pig Reproductive and Respiratory Syndrome(HP-PRRS) TJM-F92 Strain Vaccine on Immune Antibody Levels against Classical Swine Fever(CSF) and Foot-and-Mouth Disease(FMD)

Effects of attenuated highly pathogenic pig reproductive and respiratory syndrome（HP-PRRS）TJM-F92 strain vaccine on immune antibody level against classical swine fever（CSF）and foot-and-mouth disease（FMD）were studied from October 8 to November 12 in 2014,in order to optimize vaccination program of CSF,HP-PRRS and FMD and to provide scientific guidance for animal disease control and prevention work.The results showed that attenuated HP-PRRS（TJMF92 strain）vaccine had no significant effect on immune antibody level of hog cholera lapinized virus（HCLV,ST passage cell vaccine）attenuated vaccine and FMD-O inactivated vaccines（OZK/93 strain）,and single or combined use of three vaccines received good immunization effects.

H5N1 Avian Influenza Pre-pandemic Vaccine Strains in China

Objective To prepare the 4 candidate vaccine strains of H5N1 avian influenza virus isolated in China Methods Recombinant viruses were rescued using reverse genetics. Neuraminidase （NA） and hemagglutinin （HA） segments of the A/Xinjiang/1/2006, A/Guangxi/1/2009, A/Hubei/1/2010, and A/Guangdong/1/2011 viruses were amplified by RT-PCR. Multibasic amino acid cleavage site of HA was removed and ligated into the pCIpoll vector for virus rescue. The recombinant viruses were evaluated by trypsin dependent assays. Their embnjonate survival and antigenicity were compared with those of the respective wild-type viruses. Results The 4 recombinant viruses showed similar antigenicity compared with wild-type viruses, chicken embryo survival and trypsin-dependent characteristics. Conclusion The 4 recombinant viruses rescued using reverse genetics meet the criteria for classification of low pathogenic avian influenza strains, thus supporting the use of them for the development of seeds and production of pre-pandemic vaccines.

Antibody Dynamic Changes in SPF Chickens and SPF Ducks Immuned with Recombinant Avian Influenza Virus H5 Subtype Bivalent Inactivated Vaccine

To study the immune effect of recombinant avian influenza virus H5 subtype bivalent inactivated vaccine （ HSN1, Re-6 strain ＋ Re-4 strain） and to provide the basis for formulating reasonable immune procedure of avian influenza vaccine in clinical practice. A total of 12 batches of vaccines from three companies were used for the iannune of SPF chickens and SPF ducks. Each chicken or duck serum was separately collected every 3 weeks until the immunization up to the 24^th week. The serum antibody titers of Re-6 and Re-4 were detected. The results showed that the HI titers of the inoculated SPF chickens and SPF ducks roached the peak when the immune time were the 6^th and 3^rd week after the first immunization respectively; then the titer decreased gradually as time prolonged; the highest titer of SPF chickens was greater than that of SPF ducks; the high titer duration of SPF chickens were longer than that of SPF ducks ; and all the vaccines from the three companies showed a good immune effect.

Safety and Antibody Responses to Aerosolized MMR II Vaccine in Adults: An Exploratory Study

Background: There have been no reported studies involving aerosol immunization with 2 of the 3 components of MMR II vaccine—Attenuvax measles vaccine and Jeryl-Lyn mumps vaccine. Objective: To evaluate the safety and antibody responses to aerosolized Attenuvax measles strain, Jeryl Lynn mumps strain and RA 27/3 rubella component of an MMR vaccine in adults, before assessing the booster administration of this vaccine in children. Methods: A pilot study to evaluate safety and antibody responses of MMR II (Merch Sharp & Dhome Corp., Whitehouse Station, NJ 08889, USA) components administered by aerosol was carried out in 27 healthy adults of 21 to 38 years of age. All participants were followed-up during 28 days following immunization for detection of clinical adverse events. Immune response was evaluated by plaque reduction neutralization test for measles, and commercial ELISA kits for rubella and mumps. Results: Only mild clinical adverse events were noted. Despite high levels of baseline seropositivity to all vaccine components, seroresponses to measles, rubella and mumps occurred in 44%, 15% and 41%, respectively. Conclusions: These outcomes compare favorably with earlier studies of other MMR vaccines given by aerosol. Further evaluations on safety and booster immune response should be performed in children.

越南非洲猪瘟疫苗AVAC ASF LIVE(ASFV-G-ΔMGF)研究工作分析与思考

非洲猪瘟(Afcrian swine fever,ASF)是由非洲猪瘟病毒(African swine fever virus,ASFV)感染引起的烈性传染病。近日,越南正式将经临床试验验证的非洲猪瘟弱毒疫苗AVAC ASF LIVE(ASFV-G-ΔMGF)在其全国推广使用。本文对越南非洲猪瘟弱毒疫苗ASFV-G-ΔMGF相关研究数据进行了总结分析,分别从ASFVG-ΔMGF株攻毒保护能力评价、传代细胞培养株临床动物实验、野猪口服接种试验、毒力返强验证等方面,结合国内相关ASFV基因缺失株试验数据进行了分析。总结分析发现:越南上市的ASFV-G-ΔMGF疫苗株,二次免疫接种后攻毒保护效果更好,但在对野猪的口服接种评价中,其口鼻接种效果存在不确定性;随着疫苗株在动物体内的不断传代,其存在毒力返强和毒株变异风险,导致接种猪只临床症状明显;ASFV-G-ΔMGF株虽然有较好的攻毒保护能力和可靠的生产优势,但仍缺乏相关研究数据,特别是在垂直传播、交叉保护、基因突变等方面。后续仍需对ASFV-G-ΔMGF株的临床应用效果进一步评价。

免疫鸡血清新城疫病毒抗体水平与攻毒保护效果的相关性研究

为了明确不同血清新城疫病毒(NDV)抗体水平对鸡的保护效果,本研究采用重组NDV灭活疫苗(A-Ⅶ株)对鸡进行免疫,通过交叉血凝抑制(HI)试验比较A-Ⅶ株与La Sota株间的血清学差异,并采用NDV标准强毒株F_(48)E_(8)和基因Ⅶ型强毒株JSC0804对不同抗体水平免疫鸡进行了攻毒保护试验。结果显示:抗A-Ⅶ株血清用A-Ⅶ株抗原测得的平均HI抗体效价显著高于La Sota株抗原(P<0.01),约高1.5log2,而抗La Sota株血清用La Sota株抗原测得的平均HI抗体效价稍高于A-Ⅶ株抗原,但无显著差异(P>0.05),表明2种疫苗株存在一定的血清学差异。在试验条件下,所有免疫鸡经点眼滴鼻攻毒后均未表现明显临床症状,但存在不同程度的排毒现象,排毒率总体上随抗体效价升高呈逐渐下降趋势。A-Ⅶ株疫苗免疫鸡血清HI抗体效价分别达≥13log_(2)和≥14log_(2)时可完全阻止F_(48)E_8株和JSC0804株排毒。免疫鸡排毒一般仅限于攻毒后5 d内。本研究阐明了免疫鸡的抗体水平和免疫保护效果的相关性,为新城疫免疫控制提供了依据。

枯草芽孢杆菌的生理功能及其在畜禽生产中的应用

枯草芽孢杆菌是一类可形成芽孢的具有多种生理功能且对动物机体无毒副作用的理想益生菌。在饲料中添加枯草芽孢杆菌具有调节畜禽肠道功能、平衡微生物区系,提高免疫力和促生长等作用。枯草芽孢杆菌还可以作为饲料发酵菌种,经发酵后的饲料会降低抗营养因子的含量,提高营养物质的含量,从而促进畜禽对饲料养分的消化和吸收。枯草芽孢杆菌内生芽孢的特性,可以保证其在饲料生产和畜禽内环境条件下的功能稳定性以及作为疫苗表达载体的独特优势。因此,枯草芽孢杆菌在畜禽生产中具有十分广阔的应用前景。作者综述了枯草芽孢杆菌的生物学特性、生理功能及其在畜禽生产中的应用,以期为枯草芽孢杆菌在畜禽生产中的应用提供一定的参考。

一株基因Ⅲ型禽呼肠孤病毒变异株的分离及其灭活疫苗免疫原性初步评价

为了解禽呼肠孤病毒(Avian reovirus,ARV)变异株在我国的流行情况及其生物学特性和致病特点,试验采集黑龙江省某企业送检的病鸡关节组织进行病毒分离,通过RT-PCR、序列分析及常见禽类外源病毒检测鉴定,进一步通过对体外复制能力、致病性、血清交叉中和能力及灭活疫苗免疫抗体水平检测,分析其致病性、抗原性和免疫原性。结果显示:成功从病鸡关节组织中分离到1株ARV,命名为ARV-HLJ21-1690401,该分离株位于基因Ⅲ型分支,与基因Ⅲ型参考株ISR5233和42563-4-2005遗传距离较近,氨基酸序列相似性为83.4%和81.7%,而与其他基因型分离株遗传距离较远;该分离株在LMH细胞上增殖良好,对鸡胚和SPF鸡均具有明显的致病性,可引起接种鸡胚90%死亡,接种6周龄SPF鸡可引起100%发病;该分离株具有良好的免疫原性,其制备的灭活疫苗免疫SPF鸡可诱导产生较好的抗体水平。综上所述,研究成功分离到一株具有致病性和良好免疫原性的基因Ⅲ型ARV变异株,为了解我国ARV变异株的流行及遗传进化特征提供了重要理论依据。

利用大蜡螟幼虫和小鼠感染模型筛选猪链球菌血清2、3和9型三价灭活疫苗候选菌株

旨在评估临床分离的猪链球菌血清2、3、9型强毒株制备的三价灭活疫苗对小鼠的免疫保护效果。使用大蜡螟幼虫感染模型和小鼠感染模型,从临床分离的猪链球菌中筛选出血清2、3和9型强毒株各1株(SS1803、SS1803024、SS1696),检测其生长曲线和毒力因子。将菌株分别灭活及混合灭活后与佐剂混合,用4×10^(7)CFU、8×10^(7)CFU SS1803、2×10^(8)CFU、5×10^(8)CFU SS1803024、1×10^(8)CFU、5×10^(8)CFU SS1696及三价灭活苗(2×10^(7)CFU SS1803^(+)1.5×10^(8)CFU SS1803024^(+)3×10^(7)CFU SS1696)分别对BALB/c小鼠进行两轮免疫,采集血清检测特异性抗体水平,分别用3种菌株致死剂量攻毒后观察小鼠免疫保护率,同时用亚致死剂量攻毒三价苗免疫组,测定小鼠血、脑、肺、脾的组织载菌量和细胞因子IL-6、IL-12水平,并观察脑、肺、脾、肾中的组织病理变化。结果显示:3株疫苗候选菌株的毒力基因鉴定分别为SS1803:gapdh^(+)/sly^(+)/fbps^(+)/orf2^(+)/mrp^(-)/89K^(-)/gdh^(+)/epf^(+),SS1803024:gapdh^(+)/sly^(+)/fbps^(+)/orf2^(+)/mrp^(-)/89K^(-)/gdh^(+)/epf^(-),SS1696:gapdh^(+)/sly-/fbps^(+)/orf2^(+)/mrp^(-)/89K^(-)/gdh^(+)/epf^(-)。单价和三价疫苗免疫组均能产生对应免疫血清型的IgG抗体,以产生IgG1型抗体为主。三价疫苗免疫组能对2、3、9型3个菌株攻毒分别提供83.3%、66.7%和66.7%的保护率,能显著降低感染后小鼠组织中的载菌量,降低血清炎性因子水平和组织病变程度。本研究筛选临床流行率高的2、3、9型强毒株,联合制备三价灭活疫苗,能够对小鼠提供良好的免疫保护力,为猪链球菌多价疫苗的研发提供新的材料。

维氏气单胞菌弱毒株FS12001及其疫苗对异育银鲫的免疫效果

为探究由维氏气单胞菌(Av)弱毒株FS12001制备的疫苗免疫效果,将Av弱毒株FS12001制备活疫苗、灭活疫苗、ISA763A-灭活疫苗和蜂胶-灭活疫苗,腹腔注射免疫异育银鲫,同时设ISA763A佐剂、蜂胶佐剂及0.65%NaCl作为对照组。于免疫后1、3、5、7和14 d经实时荧光定量PCR(qRT-PCR)检测脾脏组织中IgM、IL-1β及LZM的基因表达量;于免疫后7、14、21、28、42和48 d尾静脉采血分离血清,检测IgM抗体水平,测定SOD和LZM酶活性;于免疫28 d后用2株Av强毒株分别攻毒各组实验鱼,连续观察记录7 d,计算各免疫组的相对保护率。结果显示,各免疫组脾脏组织中IgM、IL-1β及LZM的基因表达量高于对照组,且ISA763A-灭活疫苗组和蜂胶-灭活疫苗组的表达量显著高于其他各实验组。各疫苗免疫组血清特异性抗体水平均显著高于0.65%NaCl对照组和佐剂对照组。各疫苗免疫组的LZM活性均在28 d最高,灭活疫苗组、ISA763A-灭活疫苗组及蜂胶-灭活疫苗组SOD活性均在7 d最高。菌株AVCA07攻毒后,活疫苗组、灭活疫苗组、ISA763A-灭活疫苗组和蜂胶-灭活疫苗组的RPS分别为63%、56%、100%和56%;菌株YC170511攻毒后,以上4个免疫组RPS分别为59%、55%、93%和72%。研究表明,用弱毒株FS12001制备疫苗,注射免疫异育银鲫后均可增加脾脏中IgM、IL-1β及LZM的基因表达量,提高血清抗体水平,增强SOD和LZM酶活性,增强其抵抗Av感染的能力。

鸡胚免疫新城疫疫苗后宿主法氏囊转录组学分析

【目的】通过转录组学分析鸡胚免疫新城疫病毒(Newcastle disease virus,NDV)TS09-C株后宿主法氏囊内免疫关键基因及信号通路分子转录差异,探究免疫后宿主法氏囊内免疫相关分子的调控反应。【方法】将60只18胚龄SPF鸡胚随机分为免疫组和对照组,30枚/组,免疫组将NDV TS09-C株通过羊膜腔接种鸡胚,剂量为103.0 EID 50/枚,注射体积为0.1 mL,对照组以同样的方法接种等体积PBS。检测免疫后不同时间点肺脏、胸腺、脾脏和法氏囊组织的病毒载量。选取病毒载量最高的法氏囊组织进行转录组学测序后,筛选免疫相关差异表达基因并分析其参与的主要功能及通路。【结果】免疫后1 d法氏囊组织中即可监测到病毒,免疫后3 d病毒载量达到最高。将免疫后3 d的法氏囊进行转录组学分析,与对照组相比,免疫组有453个基因上调、98个基因下调,其中免疫相关基因有36个上调、10个下调。免疫相关差异表达基因主要富集于自噬和细胞因子-细胞因子受体相互作用的免疫相关通路。差异表达基因蛋白互作分析显示,自噬通路中富集的BCL2与其他免疫相关基因有较多互作关系,且在B细胞活化、分化、免疫系统发育等功能注释中均有参与。【结论】本研究结果揭示了鸡胚免疫NDV TS09-C株后法氏囊内调控B细胞活化、分化的潜在靶向基因及通路,为进一步研究该毒株鸡胚免疫后B淋巴细胞调控的分子机制提供新的信息。

新流腺三联灭活疫苗对禽流感病毒和禽腺病毒流行株攻毒的免疫保护试验

为了验证鸡新城疫、禽流感(H9亚型)、禽腺病毒病(Ⅰ群,4型)三联灭活疫苗对H9亚型禽流感、禽腺病毒(Ⅰ群,4型)流行毒株的免疫保护效果,采用三联灭活疫苗免疫3周龄SPF鸡,免疫后21 d采血测定禽流感H9亚型HI抗体效价,同时分别用H9亚型禽流感病毒YT株、HD株、CX株和DL株以及禽腺病毒(Ⅰ群,4型)QD株、NJ株、HA株和CZ株进行攻毒,观察疫苗对H9亚型禽流感及禽腺病毒(Ⅰ群,4型)流行毒株的免疫保护效果。结果显示,免疫组禽流感H9亚型HI抗体效价几何平均值为1∶676~1∶832,对照组试验鸡HI抗体均<1∶2;用H9亚型禽流感病毒YT株、HD株、CX株和DL株攻毒,对照组鸡9/10~10/10发病,免疫组鸡均9/10以上保护;用禽腺病毒(Ⅰ群,4型)QD株、NJ株、HA株和CZ株攻毒,对照组鸡9/10~10/10发病,免疫组鸡均10/10保护。表明新流腺三联灭活疫苗对2020-2022年分离的H9亚型禽流感病毒及禽腺病毒(Ⅰ群,4型)流行毒株感染具有良好的免疫保护效果。

幽门螺杆菌中性粒细胞激活蛋白相关疾病预防及治疗研究进展

幽门螺杆菌(H.pylori)中性粒细胞激活蛋白(HP-NAP)是新近发现的H.pylori的主要毒力因子之一,几乎所有H.pylori菌株都有表达。HP-NAP被激活后,可刺激中性粒细胞、单核细胞、树突状细胞、肥大细胞和淋巴细胞,参与炎症的发展和组织损伤。本文对HP-NAP在相关疾病的预防、治疗中的最新研究进展予以综述。

肉鹅坦布苏病毒病免疫程序初探

为了制定合理、有效的肉鹅坦布苏病毒病免疫程序,选取鸭坦布苏病毒病灭活疫苗(HB株)和弱毒疫苗(FX2010-180P株)对7日龄和14日龄浙东白鹅进行不同疫苗组合(7日龄灭活苗+21日龄灭活苗组(A组)、7日龄弱毒疫苗组(B组)、7日龄弱毒疫苗+21日龄灭活苗组(C组)、14日龄灭活苗+28日龄灭活苗组(D组)、14日龄弱毒疫苗组(E组)、14日龄弱毒疫苗+28日龄灭活苗组(F组)、未免疫组(G组))的试验,用双抗体夹心ELISA法检测免疫后不同时间的抗体含量。结果表明:弱毒疫苗免疫组产生抗体较其他组快,但抗体含量持续时间较短;灭活疫苗+灭活疫苗(A组和D组)抗体含量从免疫完成后第24~36天抗体含量均高于弱毒疫苗(B组和E组)和弱毒疫苗+灭活疫苗(C组和F组),抗体持续时间更长。建议肉鹅可在14日龄用坦布苏病毒病灭活疫苗进行首免,14d后再接种一次,可获得较高的抗体含量。

副结核分枝杆菌PanCD基因缺失株的构建及毒力评价

为了开发出能有效防控副结核病的减毒疫苗,试验采用同源重组的方法构建MAP K-10ΔPanCD基因缺失菌株,以MAP K-10菌株基因组为模板,扩增PanCD基因的上下游同源臂,构建pHAE159-p0004s-PanCD重组质粒,转化入耻垢分枝杆菌(Mycobacterium smegmatis,Msg)感受态细胞中获得噬菌体,并感染MAP K-10菌株,然后挑取单克隆扩大培养,提取基因组进行PCR鉴定;绘制MAP K-10菌株与MAP K-10ΔPanCD基因缺失菌株的生长曲线;用MAP K-10ΔPanCD基因缺失菌株感染小鼠并评价其毒力,解剖取肝脏和脾脏,分析组织荷菌量和肝脏病理变化。结果表明:成功扩增出PanCD基因的上下游同源臂,经PCR扩增和酶切鉴定成功构建出pHAE159-p0004s-PanCD重组质粒,将重组质粒电转化入Msg感受态细胞中获得噬菌体,感染MAP K-10菌株后成功构建出MAP K-10ΔPanCD基因缺失菌株;与MAP K-10菌株相比,MAP K-10ΔPanCD基因缺失菌株的生长速率明显下降;攻菌2周时,MAP K-10ΔPanCD基因缺失菌株感染小鼠的肝脏和脾脏中荷菌量显著减少;小鼠肝脏病变明显减轻。说明PanCD基因是MAP的一个重要毒力因子,构建的MAP K-10ΔPanCD基因缺失菌株可作为MAP减毒活疫苗的候选菌株。