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 31 毫秒
1.
Antibody responses in indigenous village and commercial chickens vaccinated with 12 thermostable Newcastle disease (ND) vaccine and protection levels against challenge with a virulent field isolate were determined. The antibody response of village chickens vaccinated by eye drop revealed that 30, 60 and 90 days after primary vaccination, the mean log2 HI titres were 6.1, 5.4 and 3.6, respectively, whereas for commercial chickens, the antibody response after 14, 30 and 90 days were 8.2, 5.1 and 4.2, respectively. Village chickens vaccinated orally via drinking water had mean log2 HI titres of 3.4 after 30 days. After booster vaccination, the mean HI titre was 5.4 and 3.3 after 30 and 60 days post-secondary vaccination (i.e. 60 and 90 days after primary vaccination). Antibody response of mean log2 HI titres of 2.6 was recorded 30 days after primary vaccination orally through food; 30 and 60 days after secondary vaccination (i.e. 60 and 90 days after primary vaccination), mean log2 HI titres were 5.3 and 3.2, respectively. All commercial and village chickens vaccinated by eye drop survived the challenge trial whereas village chickens vaccinated through drinking water and food had protection levels of 80% and 60% 30 days after primary vaccination, respectively. However, 30 days after booster vaccination, the protection level was 100%. At 60 days after secondary vaccination, the protection level dropped again to 80% for chickens vaccinated orally. All control chickens used in the challenge trials developed clinical ND and died 3-5 days after inoculation with the virulent virus. Supported by laboratory findings, I2 strain of NDV seemed to be avirulent, immunogenic and highly protective against virulent isolates of NDV. It may be a suitable vaccine to use in village chickens to vaccinate them against ND in rural areas.  相似文献   

2.
Virulent Newcastle disease virus (NDV) was isolated from susceptible and immune chickens following intra-ocular challenge with the Essex '70 strain. Challenge virus was isolated from the trachea and cloaca of susceptible birds until they died 7 to 9 days after challenge. This virus was isolated from immunised chickens for up to 14 days after challenge. The duration of excretion was influenced by the prechallenge serum antibody titre to NDV. It persisted longest in chickens with titres of 2(3) to 2(7) and decreased in length and frequency from chickens with titres in the range 2(8) to 2(12). Chickens with pre-challenge titres of 2(3) to 2(5) developed 2- to 3- fold increases in post-challenge titres, whereas those with higher pre-challenge titres had smaller proportional increases in titre. Excretion of virulent virus from immunised birds should be considered in the development of Newcastle disease control programs.  相似文献   

3.
From March to April 1992, 200 culled chickens sent to an abattoir in Tokyo, Japan were examined for the presence of growth agglutinating antibody in the serum. In the serological survey, 11 (5.5%) of 200 chicken sera had high growth agglutination titres against Erysipelothrix rhusiopathiae, ranging from 1:16 to 1:128. These findings indicate a high rate of erysipelas infection among chickens in the field.  相似文献   

4.
Village chickens are an important livestock for many rural families in Myanmar and other developing countries. Village chickens are kept under free-ranging conditions, with confinement only at night. Therefore, it is likely that some deaths are not observed by farmers. We conducted a longitudinal study from November 2003 until May 2004 to describe temporal patterns of mortality of village chickens in 10 villages in Myanmar. Field veterinarians first identified the numbers of birds in all chicken-owning households in each village. We then selected 307 households randomly with stratification by flock size. Each study household was then visited once monthly at which time questionnaires were completed recording current flock structure and numbers of hatchings, mortalities, sales and birds consumed since the previous visit. In addition, sera were collected from a sample of adult birds and growers. Depending on month and age group of chicken, from 71 to 231 (out of 290-307) households had discrepancies in the counts of birds. For chicks, at least one-quarter of the households had unobserved losses of at least 5 chicks per household (maximum 66 chicks); unobserved losses were less for growers and adult chickens. The median month-specific, village-specific mortality rates per 1000 bird-days at risk (counting missing birds as deaths) ranged from 0.8 to 1.7 for adults, from 0.4 to 4.7 for growers and from 8.0 to 16.5 for chicks. Across all birds, the prevalence of protective titres against Newcastle disease virus was 79% (95% confidence interval 74, 84); higher prevalences of protective titres were associated with reduced mortality rates in the following months.  相似文献   

5.
The aim of this study was to develop a strategy to control Newcastle disease (ND) in free ranging village chickens using the Nobilis ND Inkukhu vaccine (Intervet South Africa). The study was conducted at Thibella village in Qwa-Qwa, South Africa from April 2001 to October 2002. Three different routes of vaccination (administration via eye-drop, drinking water and feed) were investigated. The haemagglutination inhibition (HI) test was conducted monthly in order to measure the antibody response of village chickens after immunization against Newcastle disease. Using a South African isolate of velogenic ND virus, challenge trials were conducted to determine the efficacy of the vaccine. A questionnaire was provided to evaluate perceptions of farmers on vaccinations. The eye-drop vaccination route produced the highest HI titres ranging between 2.7 and 4.4, followed by the drinking water vaccination route with titres ranging between 2.3 and 4.0. The lowest titres were from the feed vaccination route which ranged between 1.6 and 3.0. Following the challenge, the entire control group died on the third and fourth day after infection. However, 70% of the chickens immunized by using either the eye-drop or drinking water route survived the challenge. Only 20% of the chickens from the group immunized through the feed route survived. Evidently both the eye-drop and drinking water routes were efficient in preventing disease. Necropsies showed that vaccinated chickens had mild lesions whilst control chickens had severe lesions compatible with Newcastle disease. The efficacy of the vaccine using either of the routes can be enhanced by administration of booster vaccinations at 3-month intervals during the first year of a vaccination campaign and then at 6-month intervals from the second year onwards. The majority of the owners indicated that they would prefer to vaccinate their flocks using the drinking water route.  相似文献   

6.
不同鸡新城疫疫苗免疫鸡血清HI抗体的测定   总被引：3，自引：0，他引：3  
将试验鸡分成3个试验组和1个对照组。A组鸡接种鸡新城疫系疫苗,B组鸡接种油乳剂灭活苗,C组鸡接种鸡新城疫系疫苗,并在接种疫苗后第3、4、5、6、7、9、11、13、15、20、25d采取各组鸡血并分离血清,检测HI抗体。结果表明,接种系疫苗的组,HI抗体效价均值从4.67log2上升到10log2,接种后第5d开始上升,接种后第11d达到峰值,持续6d保持高滴度抗体水平。接种系疫苗的组,HI抗体效价均值从4.67log2上升到7log2,接种后第4d开始上升,接种后第9d达到峰值。接种油乳剂灭活苗的组,HI抗体效价均值从4.67log2上升到9.33log2,接种后第5d开始上升,接种后第11d达到峰值,持续16d保持高滴度抗体水平。系疫苗HI抗体效价上升快,效价高,较适合于紧急接种,油乳剂灭活苗HI抗体效价可在高水平维持较长时间,较适合于预防接种。  相似文献   

7.
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   

8.
Prevalence studies have shown that almost 100% of free-range chickens are infected with a wide range of parasites. The infections are mostly subclinical in nature, resulting in production losses and occasionally mortality. Newcastle disease (ND), on the other hand, results in high mortality rates during epidemics. ND is a limiting factor for increasing poultry production in many tropical countries, where frequent reports indicate vaccination failures. The aim of our study was to investigate the influence of helminths on the antibody response after vaccination against Newcastle disease of free-range chickens naturally infected with parasites. Sixty chickens were divided into six groups, of which three were vaccinated against ND with a live De Soto vaccine, while the other three remained non-vaccinated. One group within the vaccinated groups and the one within the non-vaccinated group was kept naturally infected with helminth parasites, while the other two groups in each set were dewormed with fenbendazole and niclosamide, and one of each of these groups was subsequently infected with Ascaridia galli. After vaccination, all the groups were followed for 5 weeks and their antibody titres were determined weekly using a HI test. All the birds were finally challenged 4 weeks after vaccination with a virulent velogenic ND virus obtained from a field outbreak. All the vaccinated chickens seroconverted and had high antibody levels after 3 weeks, but these dropped to low levels at 4 weeks after vaccination. After challenge, the antibody titres rose in the dewormed groups but not in the parasite-infected groups. After 5 weeks, all the parasite-infected animals had significantly lower antibody titres than the dewormed animals. All the vaccinated chickens survived the challenge infection, emphasizing the importance of the cellular immune response. Further studies are needed to examine the effects of the parasitic infection on protection against ND over a longer period.  相似文献   

9.
This study aimed at isolating and genotyping Toxoplasma gondii from serologically positive free-range chickens from Argentina, and to evaluate the use of sentinel animals during a short time period of exposure to determine environmental contamination with T. gondii oocysts. Two groups of chickens on six farms were compared in this study: (i) young, 2-3 month-old broiler-type chickens reared as sentinel animals on the farms and (ii) adult chickens reared on the same farms for more than one year. Seroconversion rates of 7.0% or 5.7% were observed in sentinel broiler chickens reared for a period of 74 days (January-April 2010) or 88 days (August-November 2010) respectively, as shown by a T. gondii specific immunofluorescent antibody test. Fifty-three percent (17 of 32) of adult chickens were positive and showed higher titres than sentinel animals. Isolation of T. gondii from tissues (brain and heart) of serologically positive chickens was achieved from six of seven free-range adult birds with IFAT titres of 200 and higher. The isolated parasites were analysed by multi-locus polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The isolated T. gondii showed three different genotypes: two genotypes consisted in atypical allele combinations, and the remaining genotype had exclusively clonal type II alleles. All isolates obtained at a single farm, corresponded to the same genotype. The T. gondii genotypes observed are identical to those described in cats, dogs, chickens and capybaras elsewhere in South America. Two isolates, which showed different allele combinations in PCR-RFLP, were characterized in a mouse virulence assay. While one isolate showed a low virulence a second isolate was of intermediate virulence to mice.  相似文献   

10.
Sera from 161 dogs in the Bloemfontein area in South Africa were tested for the presence of antibodies reactive with Ehrlichia canis and E. chaffeensis by indirect fluorescent antibody testing. Overall, 68 (42%) of the dogs had significant antibody titres (> or = 1/64) against E. canis and 61 (38%) had significant titres (> or = 1/64) against E. chaffeensis. Seven (11%) dogs had higher titres to E. chaffeensis than E. canis (1/2048 and 1/1024 (2 dogs); 1/1024 and 1/512 (2 dogs); 1/2048 and 1/512; 1/512 and 1/256 and 1/512 and < 1/64, respectively). The remaining seropositive dogs had equal (n = 26; 42%) or 2-(n = 17; 25%), 3-(n = 13; 2%) or 4-fold (n = 5; 7%) higher titres against E. canis. Dogs from economically depressed, high-density suburbs (60/112; 48%) had significantly higher prevalences of antibodies against E. canis than those from more affluent, low-density suburbs (8/49; 14%) (chi 2 = 19.38, p < 0.001). Higher titres to E. chaffeensis than E. canis were found in dogs from affluent, low-density suburbs (3/49) and in dogs from economically depressed, high-density suburbs (4/112).  相似文献   

11.
Several structural components of the type III secretion systems (T3SS) encoded by Salmonella pathogenicity island (SPI)-1 and SPI-2 are exposed to the host's immune system prior to/during the infection/invasion process, making them potential vaccine candidates. In this study we evaluated whether chickens vaccinated with SPI-2 T3SS components could mount a significant humoral immune response (as measured by serum IgG titres) and whether these antibodies could be transferred to progeny (as measured by egg yolk IgG titres), and whether vaccinates and progeny of vaccinates could be protected against challenge with SE. The results of our studies show that vaccinated chickens do produce high levels of SPI-2 T3SS specific serum IgG that they are able to transfer to their progeny. It was demonstrated that vaccinates and progeny of vaccinates had lower overall countable recovered Salmonella enterica subspecies enterica serovar Enteritidis (SE) per bird in most situations.  相似文献   

12.
An enzyme-linked immunosorbent assay using the expressed protein sigma B as the coating antigen (sigma B-ELISA) for detecting antibody to avian reovirus (ARV) in chickens was developed and compared with a conventional ELISA. Both ELISA s and a serum neutralisation (SN) test were used to test the sera from experimentally vaccinated and farm chickens. The sigma B-ELISA could clearly distinguish the SN-positive and -negative sera in 38-week-old chickens. The correlation rate between SN and a sigma B-ELISA was 100 per cent (65/65), and that between SN and conventional ELISA was 84 per cent (55/65). With the sigma B-ELISA, all SN-negative sera had low absorbance values (below 0.06), and the absorbance values correlated closely with the SN titres. However, the sera which were antibody-negative by SN had various absorbance values, ranging from 0.07 to 0.39 in the conventional ELISA. Hence, the sigma B-ELISA had lower non-specific binding reactions than the conventional ELISA against sera from ARV -negative birds. Antibody against ARV could be detected by sigma B-ELISA after vaccination. Absorbance values peaked 4 weeks after vaccination at 2 weeks of age and were maintained until the birds were 27 weeks old. The results suggest that the presence of antibody against viral protein sigma B in birds may be used as a good indicator by the sigma B - ELISA for detecting immune status of a chicken flock or to detect chickens infected with ARV.  相似文献   

13.
White leghorn chickens were placed on a diet containing 0, 1000, or 3000 ppb aflatoxin B1 for 7 weeks. At the end of that time, the birds were challenged orally with the organophosphate pesticide malathion. A malathion dose of 215 mg/kg resulted in significant clinical signs of cholinergic poisoning in 4/10, 5/10, and 8/10 birds fed 0, 1000, and 3000 ppb aflatoxin B1, respectively, and the chickens required antidotal atropine 40 min later. Activity of brain cholinesterase was significantly lower than control levels in all birds given this dose of malathion, with activities being 28% +/- 6, 21% +/- 2, and 15% +/- 2 of control values (Mean +/- standard error, N = 5) if fed 0, 1000, and 3000 ppb aflatoxin B1, respectively. Plasma cholinesterase values paralleled those of brain, with significantly more inhibition in samples from birds given 1000 and 3000 ppb aflatoxins with malathion. Brain and plasma cholinesterase activities in birds fed aflatoxins and given a dose of malathion below the threshold for cholinergic signs (125 mg/kg) were also lower than activities in birds given malathion alone. Although aflatoxin alone had no direct effect on the activities of these enzymes, it appears that this mycotoxin may contribute to the esterase inhibition that is a manifestation of the acute toxic effects of malathion in chickens.  相似文献   

14.
The present study was to investigate the feasibility and efficiency of the DNA vaccine to protect chickens against very virulent infectious bursal disease virus (vvIBDV) infection. A plasmid DNA carrying VP2-4-3 genes of vvIBDV SH95 and a plasmid DNA carrying chicken interleukin-6 (ChIL-6) genes were constructed and designated as pALTER-MAX-VP2-4-3 and pALTER-MAX-ChIL-6 respectively. Several DNA vaccination experiments were performed: 1-week-old chickens were intramuscularly injected with only plasmid pcDNA3-VP2, pALTER-MAX-VP2-4-3 or mixture with pALTER-MAX-ChIL-6. The chickens at 4 weeks old were orally inoculated with vvIBDV SH95. The results showed that immunization with the mixture of pALTER-MAX-VP2-4-3 and pALTER-MAX-ChIL-6 three times conferred protection for 90% of chickens. Enzyme-linked immunosorbent assay (ELISA) antibody titres in chickens immunized together with pALTER-MAX-ChIL-6 were higher than those immunized simply with plasmid pcDNA3-VP2 or pALTER-MAX-VP2-4-3. IBDV was not detected in the bursa of the protected chickens at 8 days after challenge by RT-PCR. The results indicate that protection against vvIBDV can be achieved by using the VP2-4-3 gene of vvIBDV as a DNA vaccine. Furthermore, the simultaneous injection of ChIL-6 plasmid significantly increased the protection after challenge with the very virulent strain.  相似文献   

15.
A longitudinal study to monitor prevalence and incidence of antibodies against Newcastle disease (ND) virus and prevalence of antibodies against Avian Influenza (AI) virus in scavenging village chickens was conducted in 20 villages within 4 districts of Timor-Lesté. A total of 3600 blood samples was collected from 1674 individual birds in 300 household chicken flocks during three sampling periods (December 2008-February 2009, March-May 2009, and June-August 2009). The mean interval between household visits was 101.6±1.9 days. None of the birds enrolled in the study was vaccinated against ND or AI. A haemagglutination inhibition (HI) test was used to determine antibody titres against ND virus and a competitive ELISA and HI tests were used to detect antibody against AI virus. The bird-level ND seroprevalence pooled across all samplings (adjusted for clustering by households) was 4.4% (95% CI 3.5-5.2). The bird-level ND seroprevalence in each of the three sampling periods (adjusted for clustering by household) was 3.0% (95% CI 2.0-4.0), 6.6% (95% CI 5.1-8.0) and 3.6 (95% CI 2.5-4.6), respectively. A total of 12.6% individual birds tested ND seropositive at least once over the total study period (95% CI 10.5-14.7). The flock-level ND seroprevalence (at least one bird tested had antibodies against ND virus) pooled across all samplings was 15.9% (95% CI 13.5-18.3). A total of 35.3% flocks had a minimum of one bird being ND seropositive at least once over the study period. The bird-level incidence rate for the period between the first and the second sampling and between the second and the third sampling was 5.6 (95% CI 4.1-7.5) and 0.5 (95% CI 0.5-3.8) per 10,000 bird-years-at-risk, respectively. A total of 1134 serum samples from the last sampling period between June and August 2009 was tested for antibodies against AI virus. Only 4 samples tested Influenza A positive, indicating a bird-level seroprevalence level for Influenza A of 0.4% (CI 0.0-0.7%). These Influenza A positive samples were further tested for HI antibodies against AI virus subtypes of H5N1, H5N3, H7N3 and H9N2, but all tested negative, suggesting that the influenza antibodies in those four birds resulted from exposure to low pathogenic AI viruses of different H subtypes. Our results indicate that village chickens in Timor-Lesté are exposed to ND virus; there was a higher risk of infection during the early months of 2009 than either immediately prior or subsequent to this. No evidence of infection of village chickens with H5, H7 or H9 AI viruses was detected in this study.  相似文献   

16.
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   

17.
The objective of the present study was to develop and evaluate a local vaccine (strain TPV-1) against Fowl pox (FP) in chickens. Two separate groups of chickens were vaccinated with FP vaccine through oral (coated on oiled rice) and wing web stab routes, respectively. The results showed that the haemagglutination-inhibition (HI) antibody titres in both vaccinated groups were comparable and significantly higher (P < 0.05) than the control chickens. It was further revealed that 14 days after vaccination HI GMT of ≥2 log2 was recorded in chickens vaccinated by oral and wing web stab routes whereas 35 days after vaccination the HI antibody titres reached 5.6 log2 and 6.3 log2, respectively. Moreover, in both groups the birds showed 100% protection against challenge virus at 35 days after vaccination. The findings from the present study have shown that oral route is equally effective as wing web stab route for vaccination of chickens against FP. However, the oral route can be used in mass vaccination of birds thus avoid catching individual birds for vaccination. It was noteworthy that strain TPV-1 virus could be propagated by a simple allantoic cavity inoculation and harvesting of allantoic fluid where it survived exposure at 57°C for 2 hours. If the oral vaccination technique is optimized it may be used in controlling FP in scavenging and feral chickens. In conclusion, the present study has shown that FP vaccine (strain TPV-1) was safe, thermostable, immunogenic and efficacious in vaccinated chickens.  相似文献   

18.
鸡马立克氏病Z4＋Fc126双价活疫苗配比试验   总被引：2，自引：0，他引：2  
本研究用不同剂量的Ｚ４和Ｆｃ１２６配制成鸡马立克氏病双价活疫苗做配比试验。２个试验８种配比的Ｚ４和Ｆｃ１２６双介活疫苗免疫易感鸡，攻毒保护试验结果表明，Ｚ４无论与Ｆｃ１２６细胞结合毒还是与Ｆｃ１２６冻干毒配成双价活疫苗，均能给免疫鸡群提供坚强的免疫保护力，Ｚ４与Ｆｃ１２６间存在很强的免疫协同作用，即使Ｚ４剂量小至仅占疫苗病毒ＰＦＵ总数的１０％，这种协同作用仍能使免疫鸡群产生较强的免疫保护力。  相似文献   

19.
SUMMARY: Australian lentogenic Newcastle disease viruses were evaluated as uninactivated vaccines in Australian chickens, the response being evaluated by the production of haemagglutination-inhibition (HI) antibodies. Two viruses, V4 and PM9, induced high levels of antibody and were readily transmissible between chickens by contact exposure. Three other viruses were poorly immunogenic and poorly transmissible. Chickens vaccinated intramuscularly with the V4 strain produced higher HI antibody titres than chickens vaccinated by the orotracheal, intranasal and intraocular routes. HI antibody titres in chickens vaccinated with the V4 strain reached peak levels 3 to 5 weeks after vaccination and waned considerably during the next 2 to 4 weeks. However, low levels of HI antibody persisted for at least 36 weeks after vaccination. Intramuscular vaccination with the V4 strain of one-day-old chicks lacking maternal antibody to Newcastle disease virus resulted in 42–70% mortality and the survivors developed very high titres of HI antibody. Similar chickens inoculated orotracheally showed signs of depression and developed high titres of HI antibody, but there were no mortalities. Chickens 1-, 2-, 3- and 4-weeks-old and lacking maternally derived HI antibody to Newcastle disease virus suffered no adverse reaction to intramuscular or orotracheal vaccination. The antibody response of the 1-week-old chickens was considerably poorer than that of the older chickens. Following orotracheal vaccination with the V4 strain, chickens with low levels of maternally derived antibody responded with low levels of HI antibody. On the other hand, in the progeny of hens hyperimmunised with the V4 strain the production of active antibody following orotracheal vaccination was delayed until the level of passive antibody had declined considerably. There was no response to intramuscular vaccination in congenitally hyperimmune chickens. The minimum HI antibody inducing dose of V4 vaccine, when measured 3 weeks after vaccination of 6-weeks-old chickens, was 105.6 50% egg infectious doses.  相似文献   

20.
对利用IBDV地方野毒株所制备的囊毒和胚毒二价灭活油乳苗免疫效果进行了比较研究。结果表明,所制备的囊毒灭活苗免疫效果显著优于胚毒灭活苗和活疫苗,在接种后各个时期所产生的抗体效价均显著高于其它两种疫苗(P<0.01),最高AGP效价可达4.8log2;胚苗的免疫效果虽然差于囊苗,但明显优于活疫苗,当活苗免疫组鸡血清中已无可测性抗体时,胚苗组仍具有1.0log2的AGP效价。在攻毒试验中,囊苗组鸡对IBDV标准毒、两株野毒株的攻击均100%地获得了保护;胚苗组也均可获得80%的保护,这两种由地方毒株所制备的疫苗均未呈现出对不同毒株抵抗性的不同,而活苗组对不同毒株的攻击则分别只有53.3%、40%和46.7%的保护率,呈现出一定的差异性。  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