Is it possible to vaccinate chicks with a multi-serotype vaccine for IBV virus at one day of age?

Professor Dr. Salah Mahdi Hassan

Consultant and expert in poultry diseases and production

The question seems very strange in the current reality of the poultry industry in Iraq for many reasons that I will outline in points to be closer to understanding and knowledge. This question is a comment on what was published by the Nahrain Veterinary Network on 9/15/2024 for an article by one of the colleagues, which we must clarify to our dear colleagues working in the poultry industry sector and for all specializations and circles, and God is the Grantor of success.

The publication indicates the possibility of using more than one type of serum and specified it with the number (4 types of serum) live attenuated for the IB virus in newly hatched chicks. Therefore, the presence of the virus can be confirmed by doing a PCR test to confirm the presence of the four viruses in the chick at the age of 5 days. After that, to confirm the success of the vaccination, he can challenge any infection with the IB virus (the source of the challenge virus was not specified) at the age of 14 days, and the chicks will have good immunity.

1- Everyone must ensure that the modern and old poultry industry is a commercial sector to achieve profits and more than that it is a food security sector to provide healthy food to the consumer free from diseases, pathogens, drug residues and fungal toxins. Therefore, those in charge of this sector, especially breeders, because they are the legitimate owners of this sector, must work to avoid financial losses, and secondly, work to ensure that production is clean.

2- Today’s poultry, with its two lines, broiler and layer, are highly genetically selected commercial hybrids to achieve the two purposes, meat and high weights and a short period of time (4-6 weeks), as is the case with the commercial hybrid Rose 308, and as for layer, today breeders consider each produced chicken as a carton of eggs (360 eggs), meaning high production as well. Despite these productive positives, there must be negative effects on the bird, including morphological negatives, i.e. anatomical, physiological negatives, and immune negatives. As for the morphological and physiological negatives, I will leave them for another article, God willing, and I will address the immune negatives that are related to my observation about the post.

3- The severe genetic selection programs have caused mutations in the genetic pools of these chickens, which led to the inhibition of immune compatibility in commercial poultry, which in turn had a negative impact on the humoral immune response. While scientific sources indicate that the genetic hybrids have a strong cellular immune response, in addition to the lack of influence on the innate immunity of these poultry.

4- Scientific research, studies and field observations confirm that vaccinating chicks during the first week (1-7 days) with IB vaccines generates a very weak immune response, and that vaccinating chicks at the age of one day produces an immune response of the IgY type that is less effective compared to the immune response after 4 weeks. It is worth noting that the humoral immune response is delayed in vaccinated chicks during the first two weeks (1-14 days). (See van Ginkel et.al. 2015. Vaccine,33:2655-2661).

5- These facts seem to be consistent with the nature of growth and development of B cells in poultry, which are exposed to genetic mutation (Gene Conversion) at the age of 12-16 days of incubation inside the egg, which results in B cells being fully immune compatible at that age. This is why in-egg vaccination has been successful, and is currently widespread in the world, at the age of 18 days of incubation, in addition to the similar case at the age of one day at hatching, at which point vaccination can be carried out.

6- Consequently, after the first day, B cells carrying the IgM immune body begin to lose their compatibility property, which gives them the property of transforming to produce IgY immune bodies. This is the reason for the delay in the immune response on the one hand, in addition to making the vaccination process during the first two weeks of the chick’s life unsuccessful in protecting the birds from the diseases that are intended to be protected from. It is worth noting that there is research indicating the availability of a high level of IgM immune bodies in chicks at the age of two weeks, that they are natural immune bodies that have nothing to do with the vaccine given, which is very true. Finally, the second genetic mutation of the gland of Fabricius occurs at the age of 4-6 weeks of the bird’s life, and then the B lymphocytes are of high quality in immunocompatibility and it is called (somatic hypermutation), and then the B cells carrying IgM are converted to IgY, and thus the immune response is completely compatible and efficient.

7- Scientific sources also indicate that the use of respiratory virus vaccines in early ages of chickens leads to an inefficient humoral immune response, which appears to be due to a deficiency in the development of TLRs receptors at the age of one day, which are from the group of pattern recognition receptors (PRRs) that play a vital role in the immune response by recognizing the pathogen, compared to the presence of these receptors in chicks at the age of 4-5 weeks (see Brownlie et. al. 2009. Mol.Immunol. 46:3163-3170).

8- As I mentioned in a previous article on the Nahrain Veterinary Network page on 6/24/2024, recent studies published in the world’s first poultry magazine, Avian Disease, in its volume issued this year, indicate the dangerous role played by live vaccines for IB disease in the continued occurrence of the disease and its great losses in the poultry industry, through the link between the genes of field viruses and the genes of vaccine viruses, especially S1 sequencing of these viruses, which results in hybrid viruses that current vaccines cannot provide immunity to due to their penetration of antibodies (escape immunity) or the ability of modern viruses to cause greater harm to chickens vaccinated with current vaccines. Therefore, today scientists are calling for the manufacture of non-traditional vaccines and new technologies such as recombinant vaccines, subunit vaccines, or nucleic acid-base vaccines, meaning moving away from vaccination with the whole virus. Thus, modern vaccines are safer, more immunogenic, and provide higher protection for poultry from infectious diseases. (see Camila Cuadrado et.al. 2024. Avian Diseases 68:89-98).

9- Most of the live IB vaccines currently available in the Iraqi market contain very harmful strains to vaccinated chicks. There is a complete master’s study at the University of Mosul that indicated this harm and with visual and histological images of what the combined IB vaccines caused to the body tissues, in addition to their destruction of the tracheal cilia. It is the only study that used this criterion to determine the harm of vaccines. (See: Abdul Jabbar Mohammed Hussein Aljoburi 2012. MSc. Thesis, Mosul University).

10- We must emphasize that one of the most important elements of the success of the modern commercial poultry industry is maintaining maternal immunity, which is the main factor in maintaining the chicks’ health during the first two weeks due to the low ability of early-age chicks to respond to the specialized immune system, as we mentioned previously. Therefore, vaccinating chicks at one day of age with four serotypes of the IB virus will work to suppress maternal immunity to the disease and make the chicks vulnerable. Early infection with the field IB virus is a very serious condition because it causes damage to the oviduct tissue, especially in broiler chicks or layer chicks, which in turn leads to the occurrence of a false layer condition, in which the hen appears to be a laying hen with an active ovary, but does not lay eggs due to the destruction and perhaps disappearance of the oviduct. It leads to infection of the urinary system, kidney enlargement, and death as a result of uricemia. Here, too, the infection occurs in broiler chicks.

11- Accordingly, and for all that was mentioned above, the issue of mixing different serotypes of the IBV vaccine virus, with the number 4 as mentioned in the relevant article, is a destructive process for the bird completely, leading to deaths and a decrease in its productivity.

12- The modern strategy for using vaccines in the poultry industry sector, as one of the pillars of managing the manufacturing process, is based on the use of non-typical vaccines, especially recombinant vaccines, and today there is work in the technology of using (mRNA) in the manufacture of vaccines, which is considered a high-quality technology in the immunization process. Here it must be noted that these vaccines were designed based on the property of vaccination in the egg or on the first day as a result of the development of the immune system of poultry, as I mentioned previously.