TYPES OF POULTRY VACCINES
Types of poultry Vaccines against different diseases are to give protection against a number of viral or bacterial diseases. Many infectious diseases are ubiquitous worldwide and airborne pathogens are difficult to control even with very good biosecurity measures. For the poultry industry, the main practical method of controlling infectious diseases is vaccination. There are mainly two types of poultry vaccines are available in the market.
More importantly, Newcastle disease always associated with intestinal coccidiosis in broiler and pullet layer hen. therefore, before applying vaccine dosing of coccidial drugs running at least two days.
1. Killed or inactivated the vaccine
Killed poultry vaccines consist of a high dose of inactivated antigens combined with an oil emulsion or aluminum hydroxide adjuvant. They must be injected into each individual bird It often antigens of two or more different disease organisms are included in one vaccine (multivalent vaccine).
They give high and prolonged levels of immunity, especially when used after ‘priming’ with live vaccines.Handbook of Poultry diseases
General characteristics of killed or inactivated vaccine
- Generally slower onset of immunity
- There is no microbe replication; therefore, no tissue reaction outside that which is adjuvant dependent.
- Combinations are less likely to interfere.
- Generally slower onset of immunity
- A large amount of antigen. No multiplication after administration.
- Almost always injected to the birds
- Adjuvanting killed vaccines is frequently necessary
- More capable of eliciting an immune response in the face of an existing antibody.
- In the immune bird, additional immune response frequently is seen.
- Local immunity may be re-stimulated if used as a booster but poor if not a secondary response
- Little danger of vaccine contamination
Common Killed or Inactivated vaccines
Marek’s Killed vaccines
Mycoplasma gallisepticum inactivated the vaccine
2. Live vaccine
The live vaccine usually contains only one antigen and may be administered by spray (aerosol), via drinking water, eyedrop or by injection (optional). The antigen may either be the disease organism, which has been deliberately attenuated, i.e. made less virulent by some suitable means.
General characteristics of Live vaccine
- The live vaccine induces the rapid onset of immunity
- Tissue reaction commonly referred to as a “vaccine reaction” is possible and frequently visible in a variety of tissues.
- The live poultry vaccine contains a smaller quantity of antigen. Vaccination response relies on multiplication within the bird.
- It Can be mass administered—drinking water, spray.
- There is no need to add any Adjuvant in poultry live vaccines.
- Susceptible to existing antibody present in the bird.
- In immune bird, a booster vaccination is ineffective
- Local immunity stimulated (i.e., trachea or gut).
- The danger of vaccine contamination (e.g., egg drop syndrome, reticuloendotheliosis virus).
- Relatively limited combinations—due to interference of multiple microbes given at the same time (e.g., infectious bronchitis, Newcastle disease virus, and laryngotracheitis).
- Live vaccines may stimulate the production of local or mucosal immunity as well as general (systemic) immunity
Common Live vaccines
Infectious bronchitis disease
A smaller amount of antigen is required in live vaccines because the organism will multiply rapidly in the target organ(s). for instance, the Respiratory tract for viruses-RT and IB, the intestine -AE, the bursa of Fabricius- IBDHandbook of Poultry Diseases
Common Poultry vaccine Risk
Although the Multiplication of the vaccine organism in vaccinated birds is important and excretion may be helpful in producing a good flock immunity by the bird to bird transmission.
The spread of Poultry Diseases
Cycling of vaccine virus is advantageous in achieving good flock immunity to IBD, ND, and IB. However, cycling is undesirable with TRT or ILT. Lateral spread of vaccine viruses can be very undesirable on multiage sites. some poultry diseases are spread and take shed into the poultry farm are following
Avian Encephalopathy (AE) And Infectious Bronchitis (IB)
For example, if AE or IB H52 strain spread into older, unvaccinated groups of birds inlay, the vaccine itself may then cause production problems.
birds show a reaction after the administration of the live vaccines, for example, mild coughing or ‘snicking’ after NDV vaccination, indicating that the vaccine has ‘taken’. Unless concurrent bacterial or mycoplasma challenge is present this mild reaction disappears in a few day’s time and is not a cause for concern.
3. Recombinant vectors Vaccines
Agents that carry selected genes encoding foreign antigens are known as vectors. Genetically engineered vectors can either be used as vaccines themselves or used to produce large amounts of antigens in vitro that can then be incorporated into vaccines.
- bacteria– Mycobacterium Bovis, BCG, lactobacillus, or salmonella as vectors
- DNA viruses – poxviruses, adenoviruses, and herpesviruses
- and even plants
Advantages Using virus as VECTOR
- Viral vectored vaccines have the advantage of being able to induce both antibody- and cell-mediated immune responses without the need for an adjuvant.
- As a result, these vaccines are safe, they cannot be transmitted by arthropods, and they are not excreted in body fluids.
- They can generate antigens in the correct conformation and they can deliver more than one antigen at a time.
- They do not require complex purification.
- Their major advantage is that the antigens are synthesized within infected cells and thus act as endogenous antigens.
- they produce a “balanced” immune response compared to inactivated viral vaccines.
4. Nucleic Acid Vaccines and Reverse Vaccinology
An innovative and effective technology that works in humans and appeals to scientists may not be sufficiently economical to produce nor to satisfy animal vaccine needs. Nevertheless, two new technologies are in the process of transforming veterinary vaccinology. These are the development of DNA-plasmid vaccines and of reverse vaccinology.
In conventional vaccines, a modified live virus is injected into an animal. The virus infects cells and then uses its genome to encode viral antigens. These antigens are processed and fragments expressed on the cell surface. The expressed viral proteins are recognized as foreign by B and T cells, and the animal responds by mounting antibody or cell-mediated immune responses.
An alternative way to trigger these responses is to inject a DNA plasmid (a piece of circular DNA, usually from Escherichia coli that acts as a vector) containing the genes encoding the specific protein antigen of interest
Messenger RNA is produced by transcription of DNA and translated into proteins. Thus when it enters cells it triggers protein expression. This mRNA is only transiently expressed, and as a result, is potentially safer than persistent DNA. RNA can be synthesized so that it incorporates open reading frames that encode proteins combined with sequences at both termini that regulate translation and protein expression.
These epitopes are the essential structures that must be present in vaccines to trigger protective immune responses. Thus “vaccinomics” can be used to accurately identify protective epitopes that may then be experimentally tested in animals, a process called reverse vaccinology.
Ramzan, DVM,Poultry Veterinarian
Avian medicine and surgery in practice companion and aviary birds-Doneley Bob – CRC Press LLC 2016
Diseases of poultry 12th Edition
Essentials of Avian Medicine and Surgery-Brian Coles – Wiley-Blackwell 2007
Handbook of Foodborne Diseases Dongyou Liu-CRC Press 2019
Handbook on Poultry Diseases 2nd Edition
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Vaccines for veterinariansIan R. Tizard