Application of autogenous vaccines in the poultry industry
Autogenous vaccines, also known as autovaccines or custom vaccines, are produced by bacterial or viral pathogens or antigens from infected flocks on the same farm. Autogenous vaccines are essential for controlling emerging and evolving diseases in broiler breeder, layer, turkey, and duck segments.
In 2022, the autogenous vaccine market was USD$129.6 million with a compound annual growth rate of 5.4%, and by 2033 it is expected to reach $231.6 million. Advancement in vaccine manufacturing and rapid and accurate diagnostic assessments make these vaccines rapidly accessible to combat a variety of diseases including salmonellosis, colibacillosis, infectious bursal disease, viral enteritis, to name a few.
Various types of autogenous vaccines
All autogenous vaccines are inactivated products in the form of a bacterin, viral vaccine, or a viral/bacterin combination. Autogenous bacterin vaccines control bacterial infections in breeder birds, increase maternal antibody titers in progeny, decrease the prevalence of infection in progeny birds, and contribute to the reduction of antibiotic use in poultry flocks. Currently, the prominent autogenous bacterins produced by US manufacturers include Salmonella enterica, Pasteurella multocida, Escherichia coli, Ornithobacterium rhinotracheale, Eryspielothrix rhusiopathiae, and Riemerella anatipestifer. Autogenous viral vaccines combat viral diseases caused by emerging and evolving antigenic variant viruses in breeder birds to prevent vertical transmission of viruses, and to protect progeny through maternal immunity. Currently, the prominent autogenous viral vaccine produced by US manufacturers include infectious bursal disease, viral arthritis and tenosynovitis, viral enteric diseases, and inclusion body hepatitis.
Production requirements
Bacteria and viruses are used as a seed to prepare vaccines. These microorganisms must be the causative agent of disease and come from sick or dead birds in the flock of origin. Although with proper approval by a veterinarian, adjacent and nonadjacent flocks can utilise the autogenous product. To avoid future unauthorised use of autogenous biologics, the expired products must be removed by manufacturers from the licensed premises.
Autogenous vaccine production
Isolation, identification, and characterisation of bacteria and viruses are the main steps in autogenous vaccine production. Virus isolation and identification is a longer process compared to the isolation and identification of bacteria. Molecular methods are often used for rapid identification of microorganisms affecting poultry. Advancements in molecular characterisation methods such as type-specific real-time PCR and next generation sequencing have increased the ability for full genome characterisation of bacteria and viruses at a reduced cost. In addition, characterisation of antigenicity and pathogenicity of bacteria and viruses are done through in vivo methods.
Manufacturing process
The quality control standards for selected microorganisms are established by the manufacturer to ensure purity. In addition, safety, efficacy, and potency of the vaccines need to be evaluated at different degrees in each type of vaccine. Purity is defined as the freedom from extraneous organic or inorganic materials in vaccines. Safety is defined as the absence of properties causing undue local or systemic reactions. Efficacy is the ability of the vaccine to create the expected results. Potency is referred to as the relative strength of a vaccine. Subsequently, the antigen is inactivated with formalin or binary ethylenimine. Next step includes testing the inactivated antigen followed by batching and formulation with selected adjuvants such as in oil, oil-in- water, or water-in-oil formulations. Then, vaccine bottles are filled, and the product is tested once more for sterility before release and then labelled and stored. Final product retention bottles are also stored for quality assurance.
Legal framework of autogenous vaccines
In the US autogenous vaccines do not require a federal licensing to be produced. The Federal Regulations allow the owner of the affected birds or a state-licensed veterinarian to manufacture vaccines. Some infections that cannot be resolved by adjustments to existing commercial vaccines or by inactivated autogenous vaccines require the manufacturing of an in-house live autogenous vaccine for the exclusive use of the poultry operation. Although autogenous vaccines should not interfere with existing local and federal legislation, eradication programmes, or vaccination ban.
What to consider before implementing autogenous vaccines
It is important to consider the field challenge, evaluate the outcome of the current vaccination programme, find out the presence of immunosuppression, and figure out if existing vaccination programmes with licensed vaccines can resolve the issue. In addition, it is essential to address management and sanitary problems on poultry farms to increase the success of autogenous vaccine programme. Autogenous vaccines are primarily recommended for long-life birds such as breeders and layers to protect the progeny due to high vaccine and labour cost. A good monitoring programme is necessary for proper selection of vaccine candidates across all levels of poultry production. Production and implementation time is another important factor to consider. Federally licensed autogenous vaccines require 4-9 months to be produced and 6-12 months to be fully administered in a poultry flock in the US Although the development of autogenous viral vaccines needs more time due to more testing on the master viral seed, availability of raw material, regulatory requirements, and shipping scheduling.
Concluding remarks
Autogenous vaccines are practical options to control evolving and emerging viral and bacterial pathogens in breeder and layer poultry flocks. It is estimated that the implementation of autogenous vaccines will increase in the US for the next decade due to the constant evolution of different bacteria serovars and viral antigenic variants. However, it is required to continuously monitor regulatory framework to ensure manufacturers produce high-quality autogenous vaccines in a timely manner.
