In ovo vaccination with Embrex® technology helps support earlier

AVINEWS INTERNATIONAL| AviNews September 2024 | In-ovo Vaccination

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Recombinant vaccines pair well with Embrex in ovo vaccination technology to help deliver strong early protection against viral challenges.

At hatch, chicks can be exposed to health challenges, such as Marek’s disease virus (MDV), Newcastle disease (ND) and infectious bursal disease (IBD), and their immune systems may be too underdeveloped to protect against infection.

It can take one to two weeks for the newly hatched chick’s immune system to fully mature, creating a period of vulnerability. But there are ways to help protect chicks sooner.

Recombinant vaccines based on herpesvirus of turkeys (HVT) applied accurately through in ovo vaccination help hasten maturation of the chicken embryo immune system, shifting the onset of immunity closer to hatch and allowing the chick to respond to a disease challenge sooner.

Accurate site of injection during in ovo vaccination, in the amnion, is important to help maximize the full potential of vaccine investments and support an immune response.

In a study, chickens vaccinated against MDV at Day 17 of incubation had a lower incidence of lesions when challenged with MDV during the first five days after hatch compared with birds vaccinated at hatch, demonstrating that chicks vaccinated in ovo initiated a prehatch immune response (Figure 1).

Figure 1. An MDV challenge study compared chicks vaccinated in ovo at Day 17 of incubation with chicks vaccinated subcutaneously at hatch against MDV. It showed that the in ovo-vaccinated group had a lower incidence of lesions at Days 1 to 5 after challenge compared with the subcutaneous-vaccinated group, demonstrating that an in ovo-vaccinated chick has protection up to five days earlier.

Recombinant vaccines – such as Poulvac^® Procerta^® – that are based on HVT, are commonly used with in ovo vaccination systems.

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The HVT virus – related to MDV and conferring protection against MDV – is a large virus, and that helps make it a good candidate for gene inserts from other viruses (particularly ND virus, IBD virus and infectious laryngotracheitis).

Research has shown that replication of recombinant HVT, or rHVT, is greater when administered in ovo than when administered subcutaneously at day of age.

Since rHVT vaccines are cell-associated, they may overcome maternal antibodies and confer lifelong protection because they establish latency and periodically reactivate in long-lived birds.

In ovo vaccination not only helps with adaptive immunity through development of antibodies (humoral immunity) but also helps chickens develop cell-mediated immunity — an immune response that helps fight pathogens by destroying infected cells that display certain proteins known as antigens on their surface.

Research has demonstrated that in ovo vaccination with HVT also can hasten maturity of the chick embryo immune system. In ovo administration of HVT at Day 18 of incubation resulted in innate and cell-mediated immunity responses comparable to those of chicks 1 to 2 weeks of age..

Earlier development of the immune system via in ovo vaccination helps protect young birds against pathogens unrelated to those they’ve been vaccinated against.
In a study, a group of chicks were given an HVT in ovo vaccination.
A second group received a sham or diluent-only in ovo vaccination.
All the in ovo-vaccinated chicks were exposed to KLH, an unrelated antigen.
Unvaccinated 7- and 14-day-old chicks were also exposed to KLH.

When KLH antibodies were evaluated a week later,

100% of the HVT in ovo vaccinated chicks developed detectable antibodies to KLH,
as well as 100% of the unvaccinated 7- and 14-day-old chicks.

Only 20% of the sham in ovo vaccinated chicks developed detectable KLH antibodies.

When all the chicks were exposed to KLH a second time, the antibody activity level for the HVT in ovo vaccinated chicks was much higher compared to the sham in ovo vaccinated group.

Comparing the HVT in ovo vaccinated chicks to the unvaccinated 7- and 14-dayold chicks, the HVT-in ovo vaccinated chicks had 61% of the KLH antibody activity compared to the 7-day-old chicks (46.7% compared with 76.4%).

This shows in ovo vaccination helps enhance maturation of the chicken immune system. Previously it was thought that chicks do not develop humoral immune response until 1 to 2 weeks of age.

RECOMBINANT VACCINES PAIR WELL WITH EMBREX IN OVO DEVICES

The fast-acting line of Poulvac Procerta vector vaccines from Zoetis are designed to help protect against costly viral challenges.

The pairing of the accurate and reliable Embrex in ovo vaccination systems with Poulvac Procerta vaccines can enable great value and optimum results from a hatchery vaccine program.

Poulvac Procerta HVT-ND, offering protection against MDV and ND virus, showed 93% to 98% protection at 19 days of age when administered with an Embrex in ovo vaccination system on Day 18 of incubation.

To help protect against IBD, Poulvac Procerta HVT-IBD helps protect chicks fast and helps deliver strong overall protection to contemporary IBD virus challenges, demonstrating protection against IBD virus in chicks with high maternal antibody levels.

In a study comparing with a competitor, Poulvac Procerta HVT-IBD provided the earliest protection against a very virulent IBD challenge – Day 12 – when administered in ovo with Embrex technology.
Another study, comparing with a competitor, showed Poulvac Procerta HVT-IBD provided the highest protection against classic IBD challenges at Day 14 when administered in ovo with Embrex technology.

Poulvac Procerta HVT-IBD-ND, an advanced double insert vector vaccine, delivers powerful early protection against three diseases – MDV, IBD and ND – through a single-dose vaccine.

A study showed Poulvac Procerta HVT-IBD-ND provided protection against a very virulent IBD challenge at Day 18 when administered in ovo with Embrex technology.

Another study showed Poulvac Procerta HVT-IBD-ND provided early protection against a velogenic ND virus challenge at Day 21 when administered in ovo with Embrex technology.

Embrex in ovo vaccination technology delivers on five critical success factors for in ovo vaccination that support efficacious vaccine response and help reap the benefits of vaccine investments.

Those five in ovo technology success factors include:

Adaptive egg location;
Cconsistent shell penetration;
Thorough sanitation;
Accurate site of injection;
Maintains vaccine integrity.

Embrex technology is backed by more than 30 years of combined poultry health and engineering experience, working with poultry producers to effectively immunize chickens and address disease challenges.

Zoetis is committed to delivering on the excellence in service, training, support and in ovo technology that the Embrex brand is consistently known for around the world.

Note: Product information, registration and availability may vary per country and may change without notice. Contact your local Zoetis representative for details.

References upon request from the author

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In ovo vaccination with Embrex® technology helps support earlier, more robust immune response in chicks

Zoetis Technical Team

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