vaccines against infectious laryngotracheitis virus

The following are my experiences with egg layer chickens in the US: Good results have been seen with the rHVT-ILT vaccine to prevent early problems due to early exposure. In combination with either the CEO vaccine by eyedrop or the rPox-ILT vaccines, very good protection is seen over the long term. The rHVT-ILT by itself at day one by subQ will hold in moderate risk situations while the rPox-ILT vaccine by itself will only hold in very low risk conditions.

Interesting forum about Infectious laryngotracheitis virus. In Peru, the LT problem began in 2007, a comprehensive work of the health authority (SENASA), Poultry Farmers Association (APA) and private laboratories and state agreed to not using live vaccines for the control of LT.
We have had a remarkable success with a harmonic work between biosafety,using recombinant vaccines (HVT-IBD-LT, HVT-LT and FOWL POX- LT) and inactivated vaccines with adjuvants that stimulate the immune response at mucosal level.

Today in our lab we are working on the development of multi epitope vaccines

Dear Dr. Greg,

I already use this vaccine in many layer & broiler breeders farms as I was working in CEVA SANTE ANIMALE as a key account manager in KSA. This enabling me to study & notice the advantages of vector vaccine FP LT or FP LT AE vaccine. Yes, I agree with you that with this vector vaccine there is no way to virus recovering to return back to its virulence while on the other hand i saw how is attenuated traditional vaccine can cause virus recovering to be virulent & infect other birds which have lower immune level against ILT specially in multi-age layer farms as the virus transmitted from newly transmitted poults in production houses to older birds at neughbour houses (lower immunilty due to decline in AB after 20 weeks from vaccination with attenuated ILT vaccines) which give a chronic or mild form of ILT with moderate increase in mortality & slight decrease in production. Also i saw how much traditional attenuated vaccine has a role to transmite disease to broiler in winter season in EGYPT. This is one advantage enough to change mind towards ILT prevention while there are other advantages which are valuable like:

1- No post vaccinal reaction which in attenauted types cause respiratory manifestation which adversely affect growth & cause mortality and it needs antibiotic cost to overcome PVR .
2- with this vaccine you vaccinate against 2 or 3 diseases within one shot.
3- by using this vector vaccine specially in hot countries with strict hygeinic measures you can eradicate disease at local areas where there is no way for virus shedding beside character of ILT virus itself which are:

a- ILT virus are easily distructed by heat over 32 C
b- ILT strains have only one serotype (no variants)
c- ILT virus has only one host which is chicken so there is no carriers for ILT except chicken
while at the level of effectiveness it gave excellent results

Yasser HUSSEIN

Dear Dr. Greg,

I had worked with recombinant vaccines in my laboratory for over 10 years against a number of agents-- ILT, Gumboro, Newcastle, Marek's. These worked very well in the laboratory, giving complete protection against contolled challenge. However, in the field they were a disappointment in that small disease breaks consistently occurred. Recently in the state of Florida (USA), the recombinant ILT was used and these flocks broke with the disease. Since these vaccines worked very well in the laboratory and poorly in the field, it is clear that this is due to sanitary and vaccine application errors. I feel that if the poultry house is completely decontaminated of agents that would interfere with the replication of the vector virus, then these products will be successful.

My main problem at this time is that for a vaccine to be accepted it has to be at least as good in protecting as the currently available vaccines on the market and it has to be economical. I do not feel the ILT recombinant meets these critera at this time.

Gary Butcher

The PERU is one of the few country in the world where LT control have Not been used live vaccines. The use of recombinant vaccines (HVT-LT, HVT-IBD-LT and FP-L) associated with LT inactivated vaccine have remarkable success in controlling LT.
The marketing system in PERU of broilers is 75% live (standing), and laying hens at the end of its production is sold for consumption 100% live in standing.
That shows if possible the LT control with recombinant vaccines and oil vaccines.
In Australia in July 2012 has been reported recombination of two commercial live vaccines in cell culture leading to a new highly pathogenic virus with mortalities more than 20%, this would not be possible in the control program of PERU

I  think that a possible solution would be the use of tissue culture ILT Vaccination

Dear Mr. Manolo,

Nice to meet with you, I got your contact address from your colleague Mr. Avi. I am Dr. Mahadi Hasan working in vaccine field and more interested in recombinant vaccine. I saw you discussion and know that your company can produce recombinant vaccine, I would like to work on your vaccine and interested to import your vaccine in our country. In Bangladesh there is a huge business opportunity, there is no local manufacturer and we are fully depends on import from other MNC companies but they can't meet the full demand. So there is a gap and also there is huge demand of this new technology. I believe I will capture the full market and give you good business with your best cooperation. So if you are interested please contact me.

Waiting for your quick and positive feedback.

Best Regards,

Dr. Mahadi Hasan
Dhaka, Bangladesh

In my farm birds are producing voice like (garer) and sneezing. the age of broiler birds are10 days. killed vaccination was given at 5th day (ND and IB). I think this is ILT problem but I'm not sure about it. Mycoplasma galisepticum and synovi are negative. What can I do? Please, help me.

I totally agree with you. Attenuated live ILT vaccine (CEO) can be transmitted to low immunity chicken or unvaccinated chicken lead to vaccinal laryngotracheitis infection, and also have severe vaccine reaction but you can use live vaccine tissue culture, which has a low vaccine reaction.
About usage vector ILT vaccine, I have some comment about it , immunity and protection against ILT mainly cellular immunity not humoral immunity vector vaccine induce cellular immunity or not some scientific article about vector ILT vaccine will provide 35 % protection in high challenge area but if you like to maximize protection should be give booster dose to achieve 80% protection.

Thanks,
Dr. Mustafa Ezat
Poultry Health Division Head.