Genetic experts - any info on B21 gene?

Discussion in 'General breed discussions & FAQ' started by ChicKat, Nov 14, 2011.

  1. ChicKat

    ChicKat Overrun With Chickens Premium Member

    Does someone here with expertise in chicken genetics have information that they could share on the B21 gene?

    Here is some info -- I think from Merk Vet manual about Mareks and B21

    ..."Genetics can help by increasing the frequency of the B21 gene that confers increased resistance to Marek's disease challenge. "

    I heard that some breeds are more susceptible to Mereks....but are there breeds that are LESS? How would one find information about B21 gene? Also the statement that some chicken owners are trying to "breed in resistance to Mereks..." any thoughts? Any success stories?

    Thank you if you have insight to share...
     
    Last edited: Nov 14, 2011
  2. Henk69

    Henk69 Chillin' With My Peeps

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    Don't know about the US but inoculating (is that the word?) against Marek in Europe's fancy poultry is a disaster.
    The effect is that the strains of chickens remain vulnerable for Marek if not inoculated, while the virus persists in the flock!

    For classic Marek's the breeding for resistance shows promise.
    But new more virulent cases have arisen. I don't favor the culling of diseased flocks, but in these cases I tend to vote yes.
     
  3. ChicKat

    ChicKat Overrun With Chickens Premium Member

    Thank you for the insight Henk69.

    Surfing the net, I had found that both Europe and the US are experiencing more virulent strains of Mareks.


    Also surfing I foiund some info on the B21 gene in relation to disease resistance. The experimentors used a flock of White Leghorns and a flock of Rhode Island Reds, and it seems that there was more resistance to certain 'tumors' in the Leghorn flock. It was more technically genetic than my understanding, but it does lead to some interesting ideas.

    BTW - I love the Netherlands. Lucky me, one year I was in Delft on Easter and in Kirkenhof (spelling) in the spring. It doesn't get much better than that.

    YOUR chicken calculator link is awesome!
     
    Last edited: Nov 15, 2011
  4. Henk69

    Henk69 Chillin' With My Peeps

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    keukenhof.... [​IMG]
     
  5. flgardengirl

    flgardengirl Chillin' With My Peeps

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    I don't know about the actually genes but resistance seems to be present in some of the 'wild' or long standing feral chicken flocks. I adopted key west chickens (the first ones were straight from wild key west flocks) and am in my 3rd generation and none have ever had any illness even when the other pure breeds at my place have gotten ill. They and thier offspring never caught fowl pox either when every other bird has gotten it. They also seem resistant to mites. I had to treat some of my other pure breeds for mites and so I caught up the key wests and none had any.

    Resistance has probably been bred out of most pure breeds rather than bred into them lol. Just a guess.
     
  6. Year of the Rooster

    Year of the Rooster Sebright Savvy

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  7. cgmccary

    cgmccary Chillin' With My Peeps

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    Henk69: Don't know about the US but inoculating (is that the word?) against Marek in Europe's fancy poultry is a disaster.
    The effect is that the strains of chickens remain vulnerable for Marek if not inoculated, while the virus persists in the flock!

    For classic Marek's the breeding for resistance shows promise.
    But new more virulent cases have arisen. I don't favor the culling of diseased flocks, but in these cases I tend to vote yes.

    hello Henk.

    inoculating=vaccination (vaccinating). Has vaccinating in Europe led to more virulent strains of Marek's? How are they more virulent? Does the vaccine not work on new strains? Marek's is worldwide and long lived on a premises (50+ years) so would it matter if all or none were vaccinated? Any advantage or promise of birds that get classic Marek's but then fully recover?​
     
  8. ChicKat

    ChicKat Overrun With Chickens Premium Member

    Quote:hello Henk.

    inoculating=vaccination (vaccinating). Has vaccinating in Europe led to more virulent strains of Marek's? How are they more virulent? Does the vaccine not work on new strains? Marek's is worldwide and long lived on a premises (50+ years) so would it matter if all or none were vaccinated? Any advantage or promise of birds that get classic Marek's but then fully recover?

    cgmccary

    Just read an article in the Volume 25 Number 7 (2011) ISSUE of "International Hatchery Practice" The article is called The evolution of Marek's disease and solutions to increase protection. It is by Dr. Tariscio Villalobos, Director of Technical Marketing, Broilers Pfizer Animal Health Global Poultry.

    He says:
    "Evolutionary Trend

    One of the greatest concerns facing the poultry industry is the evolutionary trend of MDV toward greater virulence. (MDV is Marek's Disease Virus)
    Unfortunately, the great effacy of MD vaccines seems to have been accompanied with an increasein MDV virulence. Both HVT and bivlalent vaccines have provided adequate protection for a period of about 10 years. The era of CV1988 vaccines have already exceeded that of HVT or bivalent vaccines. The evolution of MDV has been mainly monitored in the USA. CV1988 was used without interruption in Eurppe and other countries since 1972 and no obvious 'vaccine failures' were reported until early 1990s.

    At present it is not clear why more virulent pathotypes are able to break vaccine immunity. An increased ocogenic potential might be a reason. However, it is also possible that the severe immunosupperssion together with stronger in vivo replication of the highly virulent MDVs could be responsible for the loss of vaccine efficacy. "


    Your local university ag. department, or an avian vet or professional hatchery may have a copy of the publication if you want to read the article in full.
     
    Last edited: Nov 16, 2011
  9. ChicKat

    ChicKat Overrun With Chickens Premium Member

    Quote:Thank you very much, I will read the thread.
     
  10. ChicKat

    ChicKat Overrun With Chickens Premium Member

    Quote:flgardengirl,

    You may really be on to something there. Only those with resistance would survive in the feral environment. Thanks for the information.
     

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