首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 46 毫秒
1.
The main theme of this project was to develop a Vero cell-adapted, thermostable NDV I-2 vaccine and evaluate its efficacy against challenge infection. For this purpose, serial passages of virus were done in Vero cell line up to 13 times and after each passage samples were subjected to heat treatment at 56°C for 40 min. After 13 passages, the virus was completely adapted on Vero cell line and cytopathic effects were observed, including syncytial formation, rounding, degeneration, and detachment of cells. Hemagglutination and infectivity titers showed that the virus was thermostable after each passages in Vero cell line. One-day-old broiler chicks (Group 1) were vaccinated orally with thermostable NDV I-2 vaccine. A commercially available thermolabile NDV LaSota was used in Group 2 used as positive control. NDV I-2 vaccine produced maximum % inhibition migration at d 6 (50%) as compared with LaSota ND vaccine (i.e., 32%). On encounter with virulent NDV I-2, 100% safety was accomplished in group 1 and 60% in case of group 2. All the birds in the control negative group had died. This study led to the conclusion that thermostable Vero cell adapted I-2 strain vaccine resulted in better immunization in broiler birds than obtained by the use of commercially available thermolabile vaccines.  相似文献   

2.
A rapid biological assay based on incubation time has been developed for determination of the potency of Newcastle disease virus strain I-2 vaccine. It is based on the observation that the interval between inoculation and the first detection of haemagglutinin (HA) depends on the titre of the vaccine inoculated. Chicken embryonated eggs were inoculated with different titres (109, 106 and 103 EID50/0.1 ml) of vaccine and incubated for 24 h. At hourly intervals, 5 eggs from each vaccine titre were tested for the presence of HA. The results showed that the HA activity was detected from 5, 11 and 15 h after inoculation with vaccine doses of 109, 106 and 103 EID50, respectively. On the basis of these results it is suggested that if there is no HA detected from 5 to 11 h after inoculation of eggs with the vaccine virus, the vaccine should not be used to vaccinate chickens as it might have an infectivity titre of less than 106 EID50/0.1 ml, which is equivalent to the recommended single chicken dose. It is concluded that measuring the time between inoculation of the vaccine virus and the onset of HA activity might provide an estimate of the titre of the vaccine within 24 h.  相似文献   

3.
The efficacy of green-coloured (GC) I-2 Newcastle disease vaccine was determined in the present study. I-2 vaccine was mixed with a green coloured dye and stored at 4°C for 6 months while assayed for the virus infectivity at a monthly interval. Chickens were vaccinated with the GC vaccine by eye drop. Serum samples were collected from all birds before and after vaccination at weekly interval for 4 weeks and tested for haemagglutination-inhibition (HI) antibody against Newcastle disease virus (NDV). These chickens were challenged with NDV virulent strain four weeks after vaccination. The results showed that there was no difference between the infectivity titres of GC and uncoloured vaccines. However, chickens vaccinated with GC vaccine produced higher HI antibody titres than chickens vaccinated with uncoloured vaccine. Results from the challenge trial showed that all vaccinated chickens survived whereas all unvaccinated chickens died. The findings from this study have shown that the GC vaccine is safe and produced protective antibodies against NDV in vaccinated chickens. Wambura, P. N., 2008. Protective antibody response produced by the chickens vaccinated with green coloured thermostable Newcastle disease virus. Tropical Animal Health and Production.  相似文献   

4.
Formulation of nano-encapsulated vaccine tablet is a novel technique for the delivery of Newcastle disease (ND) vaccine to village chickens. Vaccine tablets were prepared using gelatin, trehalose and casein as thermostabilisers and binders, respectively, and each vaccine tablet contained a nominal oral dose of Newcastle disease virus (NDV) strain I-2 for a single chicken. These ND vaccine tablets maintained a titre of 108.5 EID50/0.1 mL for 90 days at ambient room temperatures (25–34°C). When these vaccine tablets were given to village chickens, a single oral administration of the vaccine produced protective antibody response (≥3.0 log2) against challenge with virulent NDV. The findings from the present study showed that, if the vaccine tablet formulation technique is optimised, it will allow the delivery of the ND vaccine without depending on cold chains to rural areas in tropical countries.  相似文献   

5.
将表达H9亚型禽流感病毒HA基因重组鸡痘病毒疫苗连续传代至30代，取第10、20、30代重组病毒作为受检代次，进行外源基因片段的克隆与测序，以间接免疫荧光试验检验各代次的表达，并以第10、20、30代重组鸡痘病毒疫苗进行免疫保护效力试验。对各代次模板进行PCR反应，分别扩增出特异的1．7kb外源基因片段，酶切位点与原始代次相同；各代次外源基因序列与原始序列相比，仅有1个碱基发生变化，不涉及氨基酸的变化；免疫荧光试验显示各代次均有显著表达；各免疫组在免疫后第7、10、14、20天的HI抗体效价(log2)逐渐上升；攻毒后第5天各免疫组排毒率与对照组相比差异显著，各免疫组之间无显著差异。结果表明：此重组载体疫苗具有较好的遗传稳定性，经过30代的传代后外源插入基因及其表达未见变化，免疫保护效力亦与原代一致。  相似文献   

6.
The formulation and evaluation of trehalose nano-organogels for storage and oral delivery of Newcastle disease (ND) strain I-2 vaccine to chickens were carried out in this study. Trehalose sugar was blended with vegetable oil to form nano-organogels where trehalose also acted as a stabilizer against thermal inactivation of I-2 ND virus. Results from infectivity titration assay indicated that the titre of 107.5 EID50/0.1 mL was maintained after 12 weeks of storage of nano-organogel I-2 vaccine at ambient room temperature. Serology results showed that 33% chickens which were vaccinated with nano-organogel I-2 vaccine after 14 days had HI antibody titres of ≥ 3.0 log2 with GMT of 2.3. Moreover, results showed 100% of chickens vaccinated with nano-organogel I-2 vaccine had the mean antibody titres of 3.4 and 3.7 log2 at 21 and 28 days after vaccination, respectively. All vaccinated chickens (100%) survived the challenge of virulent ND virus whereas all unvaccinated chickens succumbed to challenge and died of signs consistent with ND. The findings from this study showed that the nano-organogel I-2 vaccine was stable at room temperature, safe and produced protective antibody response in vaccinated chickens. Moreover the nano-organogel I-2 vaccine was used for oral administration and hence is suitable for mass vaccination. However, optimization of the formulation of trehalose nano-organogel vaccine is required in order to achieve its application potentials.  相似文献   

7.
The complete genome sequence of the Australian I-2 heat-tolerant Newcastle disease virus (NDV) vaccine (master seed stocks) was determined and compared to the sequence of the parent virus from which it had been derived after exposure of the parent stock at 56 degrees C for 30 min. Nucleotide changes were observed at a number of positions with synonymous mutations being greater than those observed for non-synonymous mutations. Sequence data for the HN gene of a parental culture of V4 and two heat-tolerant variants of V4 were obtained. These were compared with the data for the I-2 viruses and with published sequences for parental V4 and for a number of ND vaccine strains. Sequence analyses did not reveal the ARG(303) deletion in the HN protein, previously claimed to be responsible for the thermostable phenotype. No consistent changes were detected that would indicate involvement of the HN protein in heat resistance. The majority of alterations were observed in the L protein of the virus and it is proposed that these alterations were responsible for the heat-tolerant phenotype of the I-2 NDV vaccine.  相似文献   

8.
The Newcastle disease virus (NDV) occurring in Australia is apathogenic for chickens following natural infections. Some properties of the avirulent Australian V4 strain of NDV and of 12 new isolates of NDV were compared.The viruses grew to high titres following infection of chick embryos by the allantoic cavity and allantoic fluid had infectivity titres of from 108·7to 109·5EID500.2 ml. With only two isolates did sufficient mortalities occur to allow calculation of mean death times and these were in excess of 140 h. Five of nine isolates failed to kill 100% of embryos when doses in excess of 107·9 EID50 were used. When strain V4 was inoculated into the yolk sac of 10-day-old embryos, the LD50 was similar to the ID50 obtained with allantoic cavity inoculation, and the mean death time was 103 h.The intracerebral pathogenicity index for strain V4 was 0.91 and 1.02 in two experiments. The index was not significantly reduced when the virus was taken through a further cycle of plaque purification or when the inoculum was heated at 56°C for 30 min. Chickens with maternally derived antibody to NDV were not susceptible to intracerebral inoculation with strain V4. Chickens dying after intracerebral inoculation with strain V4 had haemorrhagic and necrotic liver lesions. The intracerbral pathogenicity indices for four other isolates varied from 0 to 0.22.The infectivity of V4 and three other isolates was relatively stable at 56°C and that of another eight isolates was labile. Haemagglutinins of all viruses studied were stable at 56°C for longer than 60 min. None of four isolates tested lost haemagglutinin activity on treatment with ether.Haemagglutination-elution patterns were variable but four isolates did not elute from chicken erythrocytes after 24 h at 4°C and strain V4 and isolate PM12 did not elute after 96 h at 4°C. Six viruses, including V4, agglutinated erythrocytes from all of six test horses. The haemagglutinin activity of the remaining viruses varied between horses.Four viruses including V4 haemolysed chicken erythrocytes. Gradient centrifugation allowed the separation of an infectious and a noniffectious haemagglutinin. Haemolytic activity was associated with the infectious haemagglutinin.  相似文献   

9.
D J King 《Avian diseases》2001,45(2):512-516
In a study of low-virulence Newcastle disease virus (NDV) isolates from poultry, 38% of the isolates had a more thermostable hemagglutinin than the lentogenic reference strains B1 and La Sota or live vaccines derived from those strains. Whether those strains with a more thermostable hemagglutinin are truly indigenous or whether they could have originated from vaccines used in the flocks was unknown. Seven monovalent NDV vaccines of B1 or La Sota type and reference B1 and La Sota strains were heat treated at 56 C to select variants more thermostable than the parent virus. Four thermal treatment cycles were completed, and virus propagated from the second and fourth heat treatments was assayed for changes in thermostability and antigenicity. The hemagglutinin thermostability of all vaccine and reference strain variants increased from the initial < or =10 min to > or =120 min after four treatments. Antigenic changes evaluated by hemagglutination inhibition against NDV monoclonal antibodies identified changes in only the heat-treated La Sota strains. The results demonstrate that the field isolates with a more thermostable hemagglutinin could have been derived by selection from the heterogenous NDV populations in vaccine strains and that minor antigenic changes may be a result of that selection.  相似文献   

10.
鸭坦布苏病毒病是新发的一种以蛋鸭产蛋下降为主要特征的传染病,目前仍没有疫苗可预防和控制该病。将鸭坦布苏病毒强毒（FX2010株）在鸡胚成纤维细胞（chicken embryo fi broblasts,CEFs）上连续传代培养180代,获得1株致弱毒株（FX2010-180P株）,利用该弱毒株研制了鸭坦布苏病毒病活疫苗。本研究为了测定鸭坦布苏病毒病活疫苗（FX2010-180P株）毒种的保存期,将-80℃条件下保存了16个月的原始种子批和基础种子批各取3支,进行纯净性检验、鉴别检验以及病毒滴度测定。结果表明,各批次毒种在保存16个月后,病毒纯净无污染,病毒滴度没有明显下降。把基础种子在CEFs上增殖后,低剂量接种鸭子,检验毒种的免疫原性。结果显示,用毒种增殖的病毒免疫原性良好,101.5和102.5 TCID50的剂量可以为接种鸭提供90%和100%的保护。  相似文献   

11.
The resistance of canine parvovirus (CPV) to inactivation by chemical and thermal means was investigated. CPV with and without extraneous protein was tested against 15 commonly used disinfectants at room temperature. The titres of CPV remaining after 5 minutes disinfection time were greater than or equal to those remaining after 30 minutes regardless of the presence or absence of protein. Disinfection of CPV was accomplished more quickly and at lower concentrations of disinfectants when extraneous protein was absent. Halogen compounds, aldehydes and sodium hydroxide were the most acceptable CPV disinfectants. The presence of protein interfered with the two most frequently recommended CPV disinfectants—sodium hypo-chlorite and formaldehyde. The resistance of CPV to inactivation by heat depended on the temperature and the duration of heating. Boiling (100°C) rapidly inactivated CPV. The virus was more resistant to lower temperatures. Detectable infectivity remained after 7 hours at 80°C and 72 hours at 56°C. At both 37°C and room temperature there was no significant change in infectivity titres over 72 hours.  相似文献   

12.
Forty-five avirulent Australian strains of Newcastle disease virus had been examined for antigenicity in chickens and 18 of these were tested for thermostability. Strain I2, chosen for a combination of antigenicity and thermostability, was artificially selected for enhanced thermostability. Master seed material was then prepared in minimal disease eggs, and vaccine by a further two passages in conventional eggs. Strain I2 virus at seed and vaccine level induced adequate levels of antibody in chickens vaccinated by eye drop and usually in their contacts. The serological response to oral vaccination was less certain. Antibody titres indicative of substantial protection against virulent challenge were maintained in a simulated village flock for 38 weeks by vaccination of the foundation flock on two occasions, with subsequent vaccination confined to clutches of chicks as they were produced. Strain I2 virus survived for at least 12 weeks when stored at 22 degrees C in 1% gelatin. Strain I2 is suitable for local production of thermostable vaccine in regional laboratories in developing countries.  相似文献   

13.
Observations were made on the effects of five different methods of laboratory maintenance on the infectivity and virulence of Babesia bigemina for the tick Boophilus microplus. The original isolate was highly infective and virulent, causing premature death of engorged female ticks and reduced egg production. Maintenance of the strain by syringe passage in unsplenectomised calves at six to 10 week intervals reduced both its infectivity and virulence for ticks. When slow passages were preceded by a series of rapid passages in splenectomised calves, the changes to the strain were less pronounced. The other three procedures, rapid syringe passage in splenectomised calves and tick passage in either splenectomised or intact calves, had no statistically significant effect on the characteristics measured.  相似文献   

14.
Abstract

Mortality associated with Edwardsiella ictaluri infection is a serious impediment to the commercial production of fingerling Channel Catfish Ictalurus punctatus. A patented, live, attenuated, orally delivered vaccine has been developed that offers exceptional protection against E. ictaluri infection in both laboratory and small-scale pond trials. Further vaccine development is contingent on the successful completion of large-scale field trials that accurately reflect industry conditions. This current work focuses on the validation of fermentation protocols and the optimization of downstream processing procedures to produce sufficient quantities of vaccine to conduct commercial-scale field trials. Eight vaccine serials were produced from a master seed stock (S97-773-340X2) in a 50-L floor model fermenter over two consecutive years. Following fermentation, cells were harvested, concentrated 10-fold, and cryogenically stored (?74°C). To assess processing protocols and determine shelf life of cryogenically stored vaccine, serials were tested for cell viability and vaccine potency at various intervals over 24 months. There were no significant differences in cell viability between the fresh vaccine and the stored frozen product. All serials provided a high level of protection (77–100% relative percent survival) against E. ictaluri infection in juvenile Channel Catfish and exhibited excellent poststorage viability. This data demonstrates that the live, attenuated, orally delivered vaccine can be stored at ?74°C for at least 2 years with no reduction in cell viability or vaccine potency.

Received May 17, 2016; accepted January 19, 2017 Published online April 4, 2017  相似文献   

15.
A fully attenuated apathogenic reovirus vaccine was developed by 235 serial passages of S1133 strain avian reovirus in embryonating chicken eggs and 100 additional passages in chicken embryo fibroblast (CEF) cultures, 65 of which were cultured at 32 C. Chickens with and without maternal antibodies to avian reovirus were vaccinated subcutaneously at 1 day of age and challenged via footpad at 14 days of age. It appeared that the 40th, 66th, and 100th CEF passage levels were apathogenic at doses ranging from 10(2.5) to 10(6.8) TCID50/chick. No gross or microscopic lesions of tenosynovitis developed in vaccinated chicks. Vaccinated chicks were protected against challenge; unvaccinated control chickens were not.  相似文献   

16.
利用4型禽腺病毒HLJ1701株进行灭活疫苗的研制,并对疫苗的免疫效果进行评价,为家禽4型禽腺病毒的防控提供数据及参考。将HLJ1701株用灭菌生理盐水作10~4倍稀释后,接种9日龄SPF鸡胚,37℃孵育72 h后收获感染鸡胚尿囊液,经甲醛灭活后,加白油佐剂乳化制成油乳剂灭活疫苗,对制备疫苗的性状、安全性、免疫效力等进行检验。结果显示,制备的3批4型禽腺病毒灭活疫苗(HLJ1701株)均为油包水型,黏度均在50 cP以内,对3批疫苗取样,样品经3000 r/min离心15 min,管底无水相析出。安全性试验结果显示,将疫苗按1 mL/只超剂量接种3周龄SPF鸡,试验鸡在观察期内全部健活,未出现局部或全身不良反应,表明疫苗对SPF鸡具有良好的安全性;免疫效力及攻毒保护试验结果显示,用疫苗按0.2 mL/只的剂量免疫接种3周龄SPF鸡1次,免疫接种后21d试验鸡血清中HLJ1701株的抗体平均效价可达2~8以上,使用4型禽腺病毒(HLJ1701株)接种0.2 mL/只(100 LD_(50))对免疫鸡进行攻毒,疫苗对免疫鸡的保护率均为100%。研究表明,实验室条件下研制的4型禽腺病毒(HLJ1701株)灭活疫苗的各项指标均符合标准。  相似文献   

17.
  相似文献   

18.
Abstract

The largemouth bass virus (LMBV) was characterized in cell culture, by infectivity in five cell lines of fish origin, optimum replication temperature, and ether and pH sensitivity. Viral induced cytopathic effect (CPE) appeared most rapidly in bluegill fry-2 (BF-2) and fathead minnow (FHM) cell lines where the optimum temperature for LMBV replication was 30°C. In a one-step growth curve in BF-2 cells, LMBV reached 108.6 TCID50/mL (±0.12 log SD) in 24 h. The virus showed reduced infectivity when treated with ether but was stable when held in medium with a pH 3–9 for 12 h at 4°C. These characteristics further support the classification of LMBV in the family Iridoviridae.  相似文献   

19.
某地区猪繁殖与呼吸综合征病毒(PRRSV)与中国高致病性猪繁殖与呼吸综合征病毒(hp-PRRSV)同源性极高,为了筛选适合该地区病情的疫苗,指导养殖户生产,试验选择hp-PRRS弱毒活疫苗(JXA1-R株)和PRRS弱毒活疫苗(VR-2332株)作为疫苗候选株,选取30日龄、健康状况良好、群体差异性小的断奶仔猪30头,随机分成A、B和C组,每组10头,A组注射hp-PRRS弱毒活疫苗(JXA1-R株),B组注射PRRS弱毒活疫苗(VR-2332株),C组注射相同剂量生理盐水作对照,免疫前和免疫后14、28、42、56、70、84 d采集血清,通过淋巴细胞计数、血清病毒核酸检测、血清抗体检测等分析猪体内hp-PRRS弱毒活疫苗(JXA1-R株)和PRRS弱毒活疫苗(VR-2332株)免疫应答情况.试验结果显示,淋巴细胞数量方面,仔猪免疫后,淋巴细胞数量均上升,42 d时A、B组均达到最大值,A组为19.3×109/L,B组为16.7×109/L,C组则一直处于原始水平;抗体阳性方面,14 d时A组为80%,B组为60%,C组为0,42 d时A组为100%,B组为80%,C组为0;病毒核酸阳性率方面,14 d时A组为90%,B组为100%,C组为0,42 d时,A组为40%,B组为70%,C组为0,70 d时,A组为0,B组为20%,C组为0.由此可知,hp-PRRS弱毒活疫苗(JXA1-R株)能快速诱导猪发生免疫应答、产生免疫抗体,抗体持续时间长、效价高、稳定性良好,且疫苗毒在体内存在时间短、减毒时间快、安全性高,对所研究地区猪群免疫具有优越效果.  相似文献   

20.
The response of the Houghton strain of E. tenella to monensin and lasalocid is described. Neither drug was able to completely control this strain at 125 ppm. At this concentration oocyst production was not completely suppressed by monensin in birds given ten oocysts. At higher concentrations both drugs were able to control E. tenella (H) in birds given 1 × 105 oocysts but monensin was toxic. 375 ppm monensin did not prevent oocyst production in birds given 4 × 106 oocysts. Resistance could not be developd to either of these compounds after 12 serial passages in the presence of drug. Serial passage of E. tenella (H) in the presence of monensin however resulted in an increase in pathogenecity. This greater pathogenecity was not due to a better ability to multiply in the host.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号