Vaccination Of Broilers Research Articles

Passive Protection Afforded by Maternally-Derived Antibodies in Chickens and the Antibodies' Interference with the Protection Elicited by Avian Influenza–Inactivated Vaccines in Progeny

Systematic vaccination can be applied when a disease has become enzootic in a country or region. The final goal of the approach is to control or eradicate the disease within the country. This is a long-term vaccination plan that could be applied nationwide to all commercial and backyard poultry. However, after several months of vaccination in enzootic areas, maternally derived antibody (MDA) is present in young chicks, providing some protection and/or interference with vaccination. The aim of this study was to evaluate the level of protection afforded by MDA against challenge with highly pathogenic avian influenza virus (HPAIV), and its suspected interference with current inactivated vaccines in broilers under controlled laboratory conditions. In the first set of experiments, broilers were vaccinated with inactivated vaccines containing H5N2 subtype antigens in the presence or absence of homologue MDAs and challenged with a clade 2.2 H5N1 HPAIV. In the second set of experiments, day-old broilers, either with or without avian influenza MDA, received a regular-type monovalent H5N2 AI vaccine (0.5 ml) or a concentrated (0.2 ml) AL-Newcastle disease virus combined inactivated vaccine subcutaneously. They were then challenged at 11 or 35 days of age. In conclusion, our results indicate that protection induced by day-old administration of inactivated vaccine (regular or concentrated) in the presence or absence of MDA to H5N2 AIV induces poor protection against challenge with H5N1 HPAIV and should not be recommended. Based on our results, vaccination of MDA-positive chickens at a later age (10 days) seems to be a valuable recommendation, although MDAs may still interfere with vaccination to a lesser extent because they are present up to 3 wk posthatch. Therefore, in areas with high infection pressure, when possible, two vaccinations are recommended for optimal protection. Also, it might be advisable to take into account day-old AI MDA titers when one is determining the optimal age of vaccination.

The Efficacy of Escherichia coli AroA-Live Vaccine in Broilers against Avian E. coli Serotype O78 Infection

The Efficacy of Escherichia coli AroA-Live Vaccine in Broilers against Avian E. coli Serotype O78 Infection

Comparison of the Efficacy of the Immune Complex and Conventionally Live Vaccine in Broilers against Infectious Bursal Disease Infection

Comparison of the Efficacy of the Immune Complex and Conventionally Live Vaccine in Broilers against Infectious Bursal Disease Infection

Effects of Echinacea purpurea extract on the immunological response to infectious bursal disease vaccine in broilers

Echinacea purpurea is among the most widely used herbal medicines throughout Europe and North America for the prevention or treatment of infectious diseases. However, there have been few reports on the effect of the herb in chickens. In order to investigate the immunomodulatory effect of Echinacea purpurea in fowls, 150 seven-day-old broilers were randomly divided into five groups (30 in each group). Birds in Groups A, B, and C were orally given Echinacea purpurea extract once a day at low (0.1 g, Group A), medium (0.5 g, Group B), and high (1 g, Group C) doses for seven days, while Group D and Group E, assigned as control Group I and control Group II, respectively, were given distilled water in the same amount as Groups A, B, and C. Broilers in Groups A, B, C, and D were normally immunized with infectious bursal disease (IBD) vaccine at 14-day-old, whereas Group E was neither treated with Echinacea purpurea extract nor vaccinated. Results indicated that antibody titers were higher (P<0.01) in the three Echinacea purpurea extract treated groups (Groups A, B, and C) compared with Group D on days 21, 28, 35, and 42 after treatment. The antibody titer raised more strikingly in groups treated with higher doses of Echinacea purpurea extract (0.5 g and 1 g) than lower dose (0.1 g). The IL-2 level in peripheral blood was significantly higher in Groups B and C compared with Group D (P<0.01 on day 21 and P<0.05 on days 28 and 35). No significant difference was observed between Group A and Group D. The TNF-α content in Group B was significantly higher than that of Group D (P<0.01 on day 21 and day 28, P<0.05 on day 35). Birds in Group C also showed a higher TNF-α content than Group D (P<0.05 at the three measuring dates). These results indicated that Echinacea purpurea extract significantly enhanced IL-2 and TNF-α production and antibody titers to the IBD vaccine. The Echinacea purpurea extract was also found to increase the feed conversion ratio.

The effect of aflatoxins on the immunological response to hydropericardium hepatitis syndrome vaccine in broilers

The effect of aflatoxins on the immunological response to hydropericardium hepatitis syndrome vaccine in broilers

Comparative Immune Response Pattern of Commercial Infectious Bursal Disease Vaccines Against Field Isolates in Pakistan

A comparative study was undertaken to evaluate immune response against four types of infectious bursal disease (IBD) vaccines in broilers. The decline pattern of maternal antibody titres in unvaccinate d chicks was compared with those given IBD vaccines, following different vaccination schedules. Indirect ELISA as well as challenge with field virus evaluated the immune response of these vaccines. The results indicated that immune response against different vaccines varied in accordance with the vaccine schedule and levels of maternal antibody against IBDV in the chicks. The challenge studies indicated that only those birds stayed refractory to the challenge in which either sufficient IBDV maternal antibody titres were present or the birds were challenged at least 2 weeks post IBDV vaccination, providing sufficient time for developing an effective immune response. So it is suggested to devise IBD vaccination schedule in the light of prevailing maternal antibody tires in day-old chicks of each flock.

Comparative sero evaluation of live and killed Gumboro vaccine in broilers

Infectious Bursal Disease (IBD) is a fatal disease, which is caused by a Birna virus. Vaccination is one of the most effective ways to prevent virus. Two types of vaccines (live and killed) are normally used to induce immunity. In the present experiment, comparative sero evaluation of live and killed Gumboro vaccine in broilers was carried out. For comparing the titers obtained with the two vaccines, one broiler group was vaccinated with live and the other with killed vaccine. At four points in time serum was collected from these broilers. Serum samples were collected on day 0 and day 14 of age (i.e. before vaccination was administered at 14 days of age) and subsequently on day 28 and day 42 (i.e. 14 and 28 days after vaccination). Collected serum samples were examined to determine antibody titer using the indirect ELISA method. The average maternal antibody titers were 2888.80 and 224.80 on day 0 and day 14 of age, respectively. The average combined titer of killed vaccine was 3582.1 on day 28 and day 42 and the average combined titer of live vaccine was 1513 on days 28 and 42. The efficacy of killed vaccine was higher than that of live vaccine. It was observed that live vaccine induced the desired immunity for a limited period of time. Higher antibody titers were obtained from killed vaccine after live vaccine administration. For these reasons, it is suggested to administer live vaccine first and subsequently the killed vaccine in order to obtain an immediate immune response and subsequently to maintain high antibody titers for a long period.

Anticoccidial vaccines for broiler chickens: Pathways to success

The use of live vaccines, either attenuated or non-attenuated, for the control of coccidiosis due to Eimeria infections in broiler breeder or layer chickens is well established. Use in broilers, however, has been slow to gain acceptance. This has been partly for economic reasons, but also because of perceived adverse effects on early chick growth, particularly with non-attenuated vaccines, and concerns about timely onset of protective immunity in such short-lived birds. This review describes advances in understanding of epidemiological factors and recent improvements of administration methods that have helped to allay these fears and to make the use of anticoccidial vaccines in broilers technically achievable. Topics discussed include: (1) types of commercially available vaccine, (2) vaccines in development, (3) vaccination methods and equipment, (4) basis of vaccine efficacy and immunogenic variation of parasites, (5) key factors in the survival, sporulation and dissemination of vaccinal oocysts, (6) descriptions and significance of patterns of litter oocyst accumulation and occurrence of intestinal lesions in vaccinated flocks, (7) rotation of anticoccidial vaccination and chemotherapy to restore drug sensitivity to resistant wild-type coccidia, (8) combinations of anticoccidial vaccination and chemotherapy, (9) interactions between coccidiosis and clostridiosis in broilers and compatibilities of potential control methods, (10) published performance data for live anticoccidial vaccines in broilers, (11) possible further developments of live vaccines.

Sustainable coccidiosis control in poultry production: the role of live vaccines

The development of new methods of administering coccidiosis vaccines has facilitated their use in the hatchery and thereby improved prospects for the economic vaccination of broilers. The acquisition of protective immunity to Eimeria species is boosted by further exposure to infection after vaccination. Factors that affect the reproductive efficiency of non-attenuated and attenuated vaccines are considered and the key role that oocyst production plays in establishing and maintaining uniform immunity in a flock of chickens is discussed. In addition to immunisation, a possible advantage to the application of certain vaccines is that their use could repopulate poultry houses with drug-sensitive organisms. Theoretical rotation programmes in which the use of drugs is alternated with that of vaccines are described. Variability of the cross-protective immune response between strains of the same species should be considered during vaccine development and subsequent use. The significance of less common species of Eimeria, not included in all vaccines, also needs to be assessed. An important consideration is the occurrence of pathogens other than Eimeria (such as the bacterium Clostridium) in flocks given coccidiosis vaccines and the methods by which they might be controlled. More research is required into the relationship between bacterial and viral infections of poultry and coccidiosis vaccination. Vaccines need to be developed that are simple to apply and cost effective for use in areas of the world where small-scale poultry production is commonplace. In the near future it is likely that more live vaccines based upon oocysts derived from attenuated strains of Eimeria will be developed but in the longer term vaccines will be based on the selective presentation to the host of specific molecules that can induce protective immunity. This achievement will require significant investment from the private and public sectors, and, if successful, will facilitate the sustainable control of coccidiosis in poultry production.

Immune response to Newcastle disease virus in broilers: a useful model for the assessment of detoxification of ervil seeds

Ervil (Vicia ervilia) seeds are produced in the Mediterranean region and used as a source of protein for cattle and poultry. The methods used to assess the toxic effects of legume seeds in the feed of poultry include the observation of one or more parameters, including abnormal signs, weight gain, feed consumption, gall bladder weight, pancreas weight, pancreas proteolytic and amylase activity, haemolysis of red blood cells, liver weight, liver glutathione level, liver and plasma lipid levels, and plasma lipid peroxide levels. The authors describe the use of quantitative determination of the immune response to Newcastle disease virus (NDV) vaccine in broilers as a model that can be used to assess different detoxification treatments of ervil seeds. Broiler chicks fed differently-treated ervil, supplemented as 25% of the diet, at one to four weeks of age and vaccinated intraocularly with live NDV vaccine at eight days of age, showed different immune responses at three weeks post vaccination. Immunosuppression with regards to NDV was apparent in the group of birds raised on untreated ervil supplement, resulting in a mean immune response (titre) of 798.5. Five of the six different treatments of ervil seeds resulted in different degrees of rectification of the immunosuppression, with some broilers reaching a mean NDV immune titre of 2070.6, similar to that obtained in control broilers raised on a basal diet with no ervil seed supplement (mean NDV immune titre of 2333.8; P > 0.05). The five successful treatments of ervil (in increasing order of rectification of immunosuppression in broilers, with mean NDV titres in parentheses) were: ground soaked dried ervil (971.6), ground autoclaved dried ervil (1223.1), soaked autoclaved dried ervil (1273.1), soaked dried ervil (1340.0), and ground-soaked autoclaved dried ervil (2070.6).

Significance of Infectious Bursal Disease Serology in an Integrated Quality Control Program under European Epidemiologic Conditions

In this study performed between 1993 and 1997, infectious bursal disease virus (IBDV) antibody titers and performance data were recorded in a vertically integrated monitoring scheme in order to make a follow-up from day-old parents down to the broilers at slaughter. All measured data were used two by two in a simple correlation study to calculate the degree to which they were linearly correlated. It appeared that high and/or uniform antibody titers in the parents were correlated with increased daily weight gain and decreased mortality and slaughterhouse condemnation in the broilers. Antibody titers and their CVs were negatively correlated in broiler parents and their offspring at day-old and even at slaughter. Results indicate that high and uniform antibody titers against IBDV in broiler parents are important for good performance of the broiler offspring, at least under the epidemiologic conditions of this study, which included the presence of very virulent IBDV strains in the field and the sole use of live intermediate vaccines in broilers as well as broiler parents.

Dose-Response Effects of Inactivated Newcastle Disease Vaccines: Influence of Serologic Assay, Time after Vaccination, and Type of Chickens

Knowledge of the dose-response relation of inactivated vaccines and of the factors that influence this relation is essential for the evaluation of existing vaccine potency assays and the development of new potency assays that are based on the antigen content of the inactivated vaccines. We quantified the relation between vaccine dose, serologic response, and clinical protection after vaccination for three different inactivated Newcastle disease (ND) vaccines. Qualitatively, similar dose-response curves were obtained for the three vaccines when either the serologic response or the clinical protection of specific-pathogen-free (SPF) chickens was plotted against the different vaccine doses applied. However, the vaccines differed quantitatively: doses of vaccines that induced similar antibody titers or clinical protection differed 2-8-fold. In contrast with the narrow range of antibody titers induced by a full vaccine dose, a very broad range of titers was obtained after dilution of the vaccines. At least 95% of the SPF chickens with detectable antibody in the serum were protected against a challenge with virulent Herts ND virus. The relation between the dosage of two different ND vaccines and the serum antibody titers remained markedly constant between 3 and 18 wk after vaccination. Vaccination of broilers instead of layers with a dilution series of inactivated ND vaccine resulted in significantly lower antibody levels and less clinical protection against virulent challenge. In conclusion, despite quantitative differences, we found comparable dose-response relations for the three inactivated ND vaccines studied.

Vaccination of Chickens against Ornithobacterium rhinotracheale Infection

Vaccination of young broilers with inactivated vaccines against experimental Ornithobacterium rhinotracheale challenge was found to be effective, but the results of vaccination were influenced, in a negative way, by the presence of maternal antibodies. The use of a strong adjuvant, such as mineral oil, in a bacterin was necessary to obtain good protection when maternal antibodies were present. Vaccination of broiler breeders resulted in high serologic responses and protection of their progeny against experimental O. rhinotracheale challenge up to an age of 4 wk. Vaccination of broilers with a live vaccine was found to be effective when the maternal antibody levels were low. A combination of vaccinating the breeders with a bacterin and their progeny with a live vaccine at approximately 3 wk of age seems to be the best way to protect broilers against O. rhinotracheale infection.

Field vaccination of broilers against coccidiosis

Control of coccidiosis by vaccination or by medication with anti-coccidial drugs were compared on a commercial broiler farm. An attenuated, embryo-adapted line of Eimeria tenella, a virulent laboratory strain of E. acervulina and a precocious (attenuated) line of E. maxima, used for vaccination, were given in three combinations: E. tenella alone, E. tenella plus E. acervulina or E. tenella together with E. acervulina and E. maxima. Oocysts were given via feed when chickens were 2 to 8 days old. In four trials the performance of 8,416 chickens vaccinated with E. tenella alone or in combination with E. acervulina was as that of chickens given anticoccidial drugs. The performance of 3,601 chickens vaccinated with E. tenella, E. acervulina and E. maxima was not better than that of chickens vaccinated with E. tenella and E. acervulina only. The performance of 61,772 chickens vaccinated with E. tenella and E. acervulina in four large scale crops was similar to that of the control chickens and that of the previous six crops, which had been medicated with anticoccidial drugs.

Newcastle Disease Vaccination of Broilers with High- and Low-Titered Commercial Vaccines

The virus titers of seven commercial B1 strain Newcastle disease vaccines were evaluated. A 2 log difference in virus content was found between the vaccine with the highest titer (10(8.8) EID 50/ml) and the one with the lowest titer (10(6.8) EID 50/ml). Broiler chickens were vaccinated with the high- and low-titered vaccines to compare hemagglutination-inhibition (HI) antibody and challenge responses. The effect of vaccination at different ages on the HI titers was also examined. There were no significant differences between vaccine groups in HI antibody response or resistance to challenge. However, the high-titered vaccine may provide a margin of safety with the currently used methods of mass vaccination.

Field Trials to Test the Efficacy of Polyvalent Marek's Disease Vaccines in Broilers

The efficacies of trivalent (Md11/75C + SB-1 + HVT), bivalent (SB-1 + HVT), and turkey herpesvirus (HVT) vaccines against Marek's disease (MD) were compared in commercial broiler flocks in four trials involving 11 farm locations and 486,300 chickens. In all four trials, chickens receiving polyvalent vaccines had lower leukosis (MD) condemnation rates than chickens vaccinated with HVT alone; when data were summarized for each vaccine type in each trial, condemnation rates for the bivalent- or trivalent-vaccinated groups were 56-96% (mean 78%) lower than those for HVT-vaccinated chickens. Polyvalent vaccination was clearly mor efficacious than HVT in 8 of 11 individual farms, although it did not always reduce leukosis condemnations to acceptable levels. Body weights of chickens vaccinated with polyvalent vaccines did not differ consistently from those vaccinated with HVT. Chickens inoculated with the trivalent vaccine had slightly lower overall leukosis condemnation rates (0.24%) than those inoculated with the bivalent vaccine (0.45%) in trials 1-3, where direct comparisons were made. Bivalent vaccines containing either 1,500 or 200 plaque-forming units of SB-1 virus were equally effective; thus, HVT may need to be supplemented with only small amounts of SB-1 to obtain the benefits of protective synergism. SB-1 virus did not appear to carry over from polyvalent-vaccinated flocks to subsequent HVT-vaccinated flocks in the same houses, even when old litter was used.