In ovo delivery of an immunogen containing implant

Abstract

The disclosure provides a method for administering an agent to an avian species by in ovo delivery of an implant releasably containing the agent. In one embodiment, the method is particularly advantageous for stimulating an immune response in a bird by in ovo administration of a biocompatible implant releasably containing an immunogen. The implant can provide for sustained or delayed release of the immunogen or both. The amount of immunogen that is released from the implant into the bird is preferably sufficient to effectively stimulate a primary immune response to the immunogen. Other agents which can be administered according to the method of the invention are disclosed.

Description

BACKGROUND OF THE INVENTION [0001] In the first few weeks of life a newborn chick, poult, duckling or other avian hatchling (“chick”) is relatively incompetent at producing antibodies in response to antigenic stimuli. During this period, a significant amount of resistance to infectious diseases is provided by passive immunity derived from maternal antibodies of the hen. However, the presence of passive immunity can also contribute to the immuno-incompetence of the chick during the early post hatching period. [0002] Passive immunity is transferred from the hen to the chick via the egg. IgY antibodies are sequestered from the hen's serum and secreted in the ovary and incorporated in the yolk before ovulation. The antibodies are stored in the yolk until the later stages of embryonic development when they are absorbed by the embryonic membranes and transferred to the circulation of the chick to provide passive immunity. [0003] Maternally derived antibodies provide immunological protecti...

AI Technical Summary

Benefits of technology

[0014] The present disclosure is directed to implants and methods for delivering an agent to an animal. The invention can be particularly advantageous for delivering an agent to a bird in ovo. In one embodiment, the agent can be an immunogen and the method used to induce active immunity in a young bird. This embodiment provides for stimulating active immunity in a population of birds regardless of the immune status of an individual bird. The embodiment advantageously reduces handling, administration repetition and costs associated with most presently available immunization systems.

[0015] According to a preferred embodiment of the invention, an immunogen is contained within an implant, or multiple implants, that are administered to a bird in ovo and released into the tissues after administration. In preferred embodiments, the immunogen can be released from the implant at a predetermined time. Thus, a single administration of an immunogen to a population of birds can provide stimulation of active immunity in an individual bird when the individual is sufficiently immunocompetent to mount an immune response against that immunogen.

[0016] An implant of the invention can provide for delayed release, sustained release, or a combination thereof, of the immunogen at a selected time after administration. In ovo administration of an immunogen contained in an implant has numerous advantages over conventional vaccination techniques. For example, in ovo administration can reduce the stress associated with handling of the bird. In addition, sustained or delayed release of an immunogen enables each individual bird in a flock to respond to the antigen when the bird becomes immunocompetent. Thus, the internal variability of response to immunization in a flock is reduced and overall vaccine efficacy is increased. The method also reduces vaccine reactions that are often associated with administration of modified live vaccines.

Problems solved by technology

However, the presence of passive immunity can also contribute to the immuno-incompetence of the chick during the early post hatching period.

However, the presence of maternal antibodies can also interfere with the ability of the young bird to actively respond to an immunogen through a mechanism involving antigen elimination which prevents active immunity to that antigen.

This non-uniformity of passive immune protection can significantly influence the effectiveness of a vaccination program.

Under commercial rearing conditions of poultry it is often not feasible to use an injectable vaccine or to immunize birds on an individual basis due to the large number of birds within a flock.

However, using live vaccines in the presence of maternal antibodies has a number of inherent disadvantages.

The presence of maternal antibodies to that antigen can inhibit replication of a live immunogen resulting in insufficient levels of the immunogen to stimulate an immune response, resulting in a failure to stimulate active immunity.

In addition, the consumption of maternal antibodies which were used to inhibit replication of the live immunogen can leave the animal without passive protection.

Live vaccines also cause significant reactions which can result in decreased body weight, increased mortality, increased medication costs and increased condemnations.

The stress on the animal and expense for the breeder makes this an unfeasible alternative.

In fact, one problem with any repeated immunization program is the requirement for increased handling of the animals which causes stress that can result in a significant reduction in weight gain and efficient feed conversion.

A drawback, however, is that there will be a certain percentage of animals who lose passive protection before others and are therefore vulnerable to infection before they are vaccinated.

However, such preparations do not provide adequate long-term delivery of an immunogen and may cause adverse reactions such as a granuloma at the site of injection.

In addition, there is a risk that the person administering the injection accidentally injects themselves with the preparation, resulting in an adverse reaction from the injected ingredients.

Such methods of immunization, however, are still subject to the interfering affects of circulating maternal antibodies.

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