Discussion created on 11/04/2011

Vaccines for Marek's disease

Forum: Cause of vaccination failure against Marek's disease

Dear poultry scientists, I would like to start with the new subject regarding possible vaccination failure in MD prophylaxis. From my actual experience nowadays in spite of frequent use of bivalent vaccines against MD (Rispens+HVT) or (SB1+HVT) the MDV strains with raised virulence are isolated from field cases of the disease. I know in some cases this may be due to the low hygiene conditions in farms. However I also consider in some cases farmers apply double vaccination with bivalent vaccines at the 1st and 7th day of chickens life. From my own study I found that in such cases I commonly detect DNA of virulent MDV strain and HVT strain but not Rispens in spite of proper vaccination of chickens. Therefore I am curious about your experience and explanations of this problem. Please fell free to add comments. Thank you.

Grzegorz Wozniakowski
Doctor of Veterinary Medicine
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Stephen Adejoro Dr Stephen Adejoro Dr
Doctor of Veterinary Medicine
November 9, 2011

I am happy that we now all agree that vaccination failure to Marek's disease do occur despite bivalent vaccination strategy as it is widely practiced, and this confirm our field advise that the hatchery vaccination is not a full proof guarantee for solid immunity 

You raised important factor of hygiene as a probable aetiology for vaccination failure and this seem to agree with my view of exogenous potentiating factors that include contaminated feed with mycotoxin.I strongly believe that in view of the recent knowledge on the immuno pathology of mycotoxin, certain groups of Toxin like DON and Fuminoxin may AFFECT Cytokins functions and trigger the production of non specificity to antibodies which may allow emergence of DNA of virulent MDV strain 

This is why I strongly recommend that in endemic region revaccination with HVT must be syn energized with the administration of Nanotechnology Toxin Binder to maintain the integrity and functionality of the immune system.it is worthwile to look at this challange of our field experience as a laboratory trial and this will be a good collaboration between the lab and the field for the benefit of the industry 

 

Stephen Adejoro 

Reply
November 9, 2011

Double vaccination is very interesting.

Double dose - 

Single dose applied twice (to cover missed ones). The dutch like to give Rispens in the leg muscle using data showing protection one day earlier than intramuscular 

Revaccination at one or two or three or four weeks. There are many examples where birds that are stressed (no water, or no feed [double brooding without hiting growth curves], high mortalities in the first two weeks) can not respond to vaccination and break under challenge. 

In most cases where you are having marek's disease despite vaccination concentrating on reducing early challenge can pay dividends - for example moving rearing off production farms. Had a nice example of this in Russia where all the flocks reared off farm had very little mareks while contempories reared on farm had problems. This is often more useful than double vaccination uinless there is a systematic problem with the vaccinatiion. 

See my chapter in google books http://books.google.com.au/books?id=zdVFZxlmwcEC&pg=PA49&dq=marek+morrow&hl=en&ei=8KO6TqnjKsa6-AaXq8ypCA&sa=X&oi=book_result&ct=book-thumbnail&resnum=2&sqi=2&ved=0CDIQ6wEwAQ#v=onepage&q=marek%20morrow&f=false 
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Dr.m.suresh Dr.m.suresh
Veterinary Doctor
November 9, 2011

Good article about vaccines for marek's disease. In my experience we must and do vaccinate on 1st day with HVT+SB1 and booster with HVT monovalent gives better result.

Reply
November 9, 2011

Thank you for your all your valuable opinions. I like the new vision of dr Adejoro of the influence of mycotoxins on immune system function. According to reply of dr Chris Morrow indeed the best idea is rearing off of farms, However it is obvious that in many cases the main goal is highly profitable and fast production without rearing off farms. However I am thankful for your opinion and I always refer your data regarding economic impact of MD in my papers as well as PhD thesis. I am also thankful for the opinion of dr Suresesh. Unfortunately SB-1 in forbidden to apply for vaccination in many EU countries due to higher risk of the incidence of lymphoid leucosis in chickens. I know the practice of boosting with HVT but since the new very virulent plus variants of MDV appeared it may be not enough to protect chickens.
Another question: Do you think that revaccination with bivalent vaccine may cause overloading of immune system of birds so they are more susceptible to infection with very virulent MDV?

Reply
November 9, 2011
Past history shows that HVT monovalent vaccine remained protective till early 1980's - then very virulent viruses (vvMD) emerged.
Industry started bivlent vaccine (serotype-2 MD vaccines combined with HVT) which gave good protection till early 1990s - then very virulent plus (vv+) MD emerged.
This suggests that current management of intensive poultry farming is favouring increase in the virulence of field viruses that are not prevented by the existing vaccines.
The last hope remains with the rispen vaccine. At the moment there appears no development in pipeline that can replace rispen.
When more protection is needed, Rispen vaccine strains may be added to make a trivalent combination.
There appear two important factors to control virulent MD:
1. Reduction of early challenge.
2. The use of Rispens vaccine where necessary.
Moreover, immunosuppressive diseases (IBD, CAV, mycotoxins), coccidiosis and stress during first few weeks of live can prevent adequate immunological response to MD vacination.
DR ANJUM
Reply
Maqsood Jaffery Maqsood Jaffery
Doctor of Veterinary Medicine
November 9, 2011
A lot has been written about problem of Vaccine failure agaist MD. Vaccination is not the sustitute to better management & Biosecurity. If the chicks travell for long distances from hatchery to farm will also lessen the efefctiveness of vaccination. At farm brooding, rearing if not appropriate causes stress resulting in lesser protection from vaccination. Only healthy birds get better immunity. Immuno suppressive disease like IBD & CIAV (Chicken Infectious anemia viral disese) outbreak during early age wil adversly affect the immunity buildup against MDV. In my opinion combination os Rispen +HVT is working well if administered as per standard procedures. Chiks remain healthy during brooding & rearingwill also help in efficay of vaccine against MD. Other immunosuppressive factor are the mycotoxins. As mentioned by Stephen Adejoro about the role of mycotoxins, it is really an important factor & should be taken care of. Idea of Dr.Chris Morrow is again saving the new chicks from challange of MD field virus. If there is higher challange due to unhygeinic conditions, multiage, breach in biosecurity measures, there are chances of vaccination failure.
In my opinion one vaccination with Rispen +HVT properly handled & administered is enough. It should be emphasized that there should be least stress in transportation, brooding & rearing of chicks. By proper vaccination against IBD & CIAV, better results can be obtained. Feed should be as per requirement of chicks & toxin free. In my opinion presence of mycotoxins in feed is one of the definite reasons of vaccination failure not against MDV but against other diseases also. Better Biosecurity & environmanegemnt is also helpful in efficay of vaccine for buildup of immunity.
Maqsood Jaffery
Reply
Nabil Tanios Nabil Tanios
prof. Poultry Diseases
November 9, 2011

In spite of bivalent vaccination against Mareks disease, I agree that some cases appears and we can summarise the main causes as follows:
1. Improper handling and storage of vaccines.
2. Delay or insufficient vaccination.
3.Bad hygiene either in hatcheries or in poultry farms.
4.stressed birds e.g overcrowding,bad ventilation,omphalitis and vertical transmitted diseases.
5.Immunosuppressor factors either from food, causative agents...
6.Genetic susceptibility of some breeds especially some native breeds.
7.Revaccination may correct missing unvaccinated birds.

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Danka Maslic-Strizak Danka Maslic-Strizak
Veterinary Doctor
November 9, 2011

I think they Mosqsood Jaffery and Nabil Tanios completely right about what the main reason for the occurrence of Marek's disease vaccines are considered improper handling and respect for the biosecurity measures in the process of keeping poultry.
Farms where Marek's disease occurred in one or two times you should not settle for a longer period (six months) and the next two times done disinfection.
A large number of different vaccination certainly conditioned by weaker immune response.

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Karna Bahadur Bohara Karna Bahadur Bohara
Master of veterinary science (M Sc)
November 10, 2011
During late 90s MD was the bigest enemy threatning our poultry industry in Nepal.The incidence Rate in egg layers was more than 67 % and gradually shifted to broiler Industry too.I was given responsibility to handle the situation.It was a big challange for me as young boy and I consulted to Dr RL wittor of USA,Dr Vnogopalan of UK ,Dr Davidson of Israel & many more experts around world. The incidence rate was brought to around 4 to 5% from 67% in 3 to 4 years of time.
Now sporodic cases MD vaccine failure are seen increasingly evidenced again.My fight with MD remained almost regular in last 15 years,I realised win win sirtuation a number of times but never wined the battle.I had tried a number strategies only a few resulted with very satisfectory results which I would like toshare with you.
Whether you go for single vaccination(it should be propely done without mising a single birds and damaging the quality of Rispens vaccine+HVT at hatchery) or dauble vaccination at different interval( A week apart) it gave the smame result but best results was acheived only when
Best hygiene and biosecurity was maintained
Growing pullets was done in a clean environment ,enough away from laying farm
Mycotoxin level in feed raw matterials were regularly monitored and contaminated pullet feed was discarded
My experience says the most imortant factor which play greatest role in MD vaccination failure is USE OF MYCOTOXIN COTAMINATED FEED from day one to 12 th week of age and Presence of Imunosuppresents particularly up to 6 weeks of age of the pullets.
Dr Bohara
Reply
Dr Mahendra Chaudhari Dr Mahendra Chaudhari
M.V.Sc. Animal Nutrition Masters Degree Veterinary
November 10, 2011

Dear G. Wozniakowski,

Thanks for forum on Marek's disease. I have seen many cases of Marek’s in broiler breeders. I feel the first vaccination at hatchery is very important. Proper vaccination at hatchery before chicks goes in to other environment is important. The vaccination method is equally important specially vaccinator needle guaze ,mixing, keeping vaccine cool. I had seen lapses in above leads to improper vaccination. We need to make sure that every chick is vaccinated. Amongst various types we used 2doses HVT +1 dose SB1 commonly , in some cases 2 HVT + 1 dose Rispens in case of non availability of Rispens we tried 2 doses of HVT + 301 Marek’s vaccine at day old. I have seen first vaccination at Day old is important. I saw few farmers are repeating vaccine on 5th day or 18th day and claiming they are getting good response. However I did not see and advantage of doing 2nd vaccination in filed. It is very difficult to see response in multiage group farms. Proper IBD immunized flocks less problem noted. Similarly we have seen problems in coccidiosis out break flocks. Flocks brooded till 8 weeks in isolated new premises proven good results if flocks grown in minimal stress conditions. Doing double dose SB1 , we noticed cancers lesion in few cases around 4o week age. Many times the problem I had seen is due to improper vaccination or missing few chicks while vaccinating at hatchery at day old.

Dr Mahendra Chaudhari

Reply
Dr Jaydip Mulik Dr Jaydip Mulik
Master Of Veterinary Science & Master of Business Administration
November 10, 2011

Dear Grzegorz Wozniakowski ,

Thanks for posting such wonderful topic for discussion. All experts in this field have expressed their views and i also supports the same. The main reasons for any vaccine failure including Marek's disease vaccines on field are closely related to...
1) Hygiene
2) Biosecurity
3) Feed Toxins
4) Drinking Water Quality
5) Environmental factors.
6) Improper storage & handling of vaccines.
7) Improper Nutrition etc.

Regards,

Dr Jaydip

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Dr Wisal M.Khan Dr Wisal M.Khan
Doctor of vet Med
November 10, 2011

I am fully agrre with the coments of Dr AD Anjum, important thing which i want to discuss here is vaccination prepartion at the Hatchery Level, as the water Bath Temp should not be high and the time period for the vail of vaccince vail may be less than 1 minute time , as most of the vaccince lost its efficay before applying .
2nd thing is that if the Farm has a history of MD than a proper cleaning and disinfection must be done the chicks arrived there.
3rd thing is that the only way for the Virus infection is the wk of life if there is any chances of fielf infection so at the First 2 wks a good bio security is important and even latter is important.
3rd thing is provide Toxin Free Feed for the first 5-7 wks so that less imune supersion.
4th is that preven the flock from some very imune supresive disease in 5wks like IBD/CAV/COCCI etc.
5th is that provide some good vitamins suplelments at the start of the flock with additionaly added of Vit E& Sel in feed and in D/W.
I hope that by Following some of the nice coments from the Group one can easily protect his Flock from the Marek's disease.
Thanks

Reply
Stephen Adejoro Dr Stephen Adejoro Dr
Doctor of Veterinary Medicine
November 10, 2011
I am very happy that this topic is becoming very stimulating, and shows that it has become a global issue not restricted to tropical climate alone. I congratulate Dr Worniakowski for presenting this problem for discussion
Engormix editor may come up with a summary of possible recommendations that farmers may adapt on the field.

The major issues may include:

Acceptability of the problem of vaccination failure
The role of biosecurity and handlings
The role of mycotoxin and immunosuppressionion
The critical age of 12 weeks and onset of outbreak
The implications of LARGE MOLECULE TOXINS LIKE DON in affecting memory function of cytokins and ccausing non specific antibodies prodonuction

Can we come up with a prophylactic suggestion on the management of mareks vaccination failures?

ADEJORO


Reply
Rudolf Hein Rudolf Hein
Consultant Micobiologist
November 10, 2011

Several of the possible causes of the MDV failures have been put forward.I would like to add some comments re possible failures.
In several cases the Marek's disease vaccines are simulteneously applied with other vaccines ,one has to make sure that these vaccines do not interfer with the MD vaccine (only use these vaccines as recommended by the vaccine manufactory),in addition in most cases antibiotics like gentamycin are added extra to the diluent ,one has to be carefully with the dose since we have shown that incresed doses of antibiotics have an effect on the MD titer,
MD vaccines like basically all vaccines will not even if applied properly provide 100% protection further on a vaccination will not provide immediate protection ,it will take some days to provide full protection (see also comment Chris Morrow).In ovo vaccination may reduce the delay in onset of immunity.
Maternal antibodies specific for MDV type 1 ,2 and 3 have shown in laboratory trials to interfere with the onset of immunity however it is not known how far this plays a role in the field.Use only low passage vaccines since it has been clearly shown that high passage levels of HVT and CVI988(Rispens) will reduce its efficacy despite it will induce higher vaccine (PFU) titers.

Reply
Dr.m.suresh Dr.m.suresh
Veterinary Doctor
November 10, 2011

Possible cause of Marek's disease virus spresd through feathers. So that we should take care to complete burning of feather before placing chicks.

Reply
November 11, 2011
Thank you again for an interesting discussion. I agree with your all opinions. It is interesting that personally I have taken very rarely into account the role of mycotoxins in prophylaxis of Marek's disease. I think the main problem in achieving successful vaccination is the hygiene and early infection as it was pointed out by dr Adejoro, dr Mulik and dr Khan. The idea of burning feathers would be good solution to prevent early infection. By the way what is your experience of broiler flock vaccination with HVT since in a part of Europe including Poland this is the main vaccine use for these chickens?
Reply
November 12, 2011

Few years back, we compared performance (live weight, FCR, etc) of HVT vaccinated broilers with non-vaccinated broilers EXPERIMENTALLY. HVT vaccinated broilers had better performance BUT the difference was not statistically significant. So the use of Marek's disease vaccine did not become popular for commercial broilers in Paksitan.

Reply
Nadim Amarin Nadim Amarin
Key Account and Poultry Vaccine Technical manager - MENA Area
November 13, 2011

All the participants covered the topic very well especially Mr. Nabil tanious and Mr Ahmad froM Egypt and Saudi Arabia.

In Jordan the main problems of Marek's disease detected due to failure of vaccination (due to improper cold tranefer of the vaccine from the country of origin) so all the companies now vaccinating their layer twice in Hatchary with different source of MD vaccines and Rispin approved to give good protection against MD.

But i believe the fear from Lymphoid leukosis due to MD is not very clear unless you have reliable publication?!

Reply
November 13, 2011
Indeed the incidence of Lymphoid leukosis may be induced by MDV strains belonging to 2nd serotype including SB-1. There were some experimental studies conducted by Bacon et al. (1989) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC247718/pdf/jvirol00069-0046.pdf and Ewert et al. (1999) http://www.ncbi.nlm.nih.gov/pubmed/10696433.
That's why the use of SB-1 based vaccines is not allowed in EU countries.
Reply
Dr Wisal M.Khan Dr Wisal M.Khan
Doctor of vet Med
November 14, 2011

Marek's disease vaccination in broiler , i think due to genitic potential and the age of Marketting is reduced from 48/42 to up to 35 days in some countries and also in these countries the live weight is not even more than 1.5kg so for this case i will say that using of the MD alone is not good , how ever if using with some vaccince like IBD at DO may be good , but the cost will be higher and now if some one take care for the cost reduction in this instances no need for it just IBD alone is also available if there is a real thread in the area , and if not than Normal IBD vaccination will protect the birds .
How ever i did not seen / notice any much difference in the weight for the DO MD vaccinated and un vaccinated chicks .
For the Failure of MD due to Transportation or storage is always Q mark .
Yes it is good to vacciante twice so that it will give more protection and also if any chicks were miss in first short may get the vaccince in second one , how ever it need some rest period between the two shorts of vaccinations which may be about 2-3 hrs .
Thanks

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