Moving Forward- Breeding for Resistance to Marek's Disease

Discussion in 'Emergencies / Diseases / Injuries and Cures' started by sassybirds, Jun 5, 2014.

  1. Nambroth

    Nambroth Fud Lady

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    I understand your frustration. I really do. I have wondered this, often. One thing we must realize is that Marek's is a complex Alpha Herpesvirus...
    To put it into perspective, how many viruses of human beings have we not even developed ANY vaccine for? How many still plague us, despite millions (billions?) spent in research, and being able to communicate with patients (unlike dealing with a sick animal, that can not describe exact symptoms in detail...). Ironically, the research into and development of a vaccine for MDV-1 Chicken Marek's Herpesvirus led to the research that developed the first human vaccine against HPV (Human Papilomavirus), which is cervical cancer. Like Marek's virus which can cause lethal cancer within our birds, HPV is a virus that causes cancers in humans.
    In fact, some of the herpesvirus family is known occasionally to cause cancer in humans, too. Here's some reading: http://www.faseb.org/portals/2/pdfs/opa/2008/HPV.pdf

    Anyway, my point is... what we have is surprisingly good. Not great, but... we can't say the same for some human disease.

    Oh no, I'm so sorry. This is just the worst thing to have to do. My heart breaks for you.
     
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  2. Northie

    Northie Chillin' With My Peeps

    There's a bit of talk on here detailing how breeding for resistance should be a very scientific affair with a controlled environment and numerous tests... It could be done that way for sure, but I don't know how many of us have the means to do it. If people can and do take that approach, awesome, please share the results and what you learn along the way! (Pretty, pretty please with the kuuuuuuutest little fluffy chick top!!! ;) )

    For me it's more or less going to be a matter of simply not just giving up. Limiting the variables that I can and hodge-podge working through it as I go. If I want to keep chickens I have to. I can't get a hold of small batches of vacine and I have very little access to vet care unless I go to the university, not to mention I chose breeds that are known for being broody and could raise their own chicks any time... so personally vaccinating isn't a feasible option... That sucks... And it's why I'm following this thread closely.
     
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  3. tridentk9

    tridentk9 Chillin' With My Peeps

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    I mentioned original sin the other day meaning to explain more and then forgot. It's really Original Antigenic Sin, it's the hypothesis that contact with one version of a viral disease makes it even more difficult for the body to produce antibodies to different serotypes of the same disease. The memory cells are primed to work against serotype A and don't realize serotype A1 needs different antibodies. http://en.m.wikipedia.org/wiki/Original_antigenic_sin
    This *might* explain why vaccines made from HVT (Herpes Virus Turkey) don't really protect against MDV1.
     
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  4. JensChickies

    JensChickies Chillin' With My Peeps

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    That is very interesting that they discovered the HPV vaccine while researching Mereks. Thank you for the information. It's just frustrating to loose a bird to Mereks. All the heart ache we go through. Is there any way to improve the vaccine that is out now for it?
     
  5. Nambroth

    Nambroth Fud Lady

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    Very interesting!! It is something to think about for sure.


    I understand your frustration. I have read that they are working on an improved vaccine, but it may be years before we see it, if at all, as it goes through trials and approval processes. I don't know of it will be available to average keepers or not... It probably depends on administration methods, etc.
     
  6. seminolewind

    seminolewind Flock Mistress Premium Member

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    I hope its the end of a long week, too. My poor chickens will have to put up with my extra kissy huggy time with them-they'll be hiding from me. Well, not all of them, LOL
     
  7. chooks4life

    chooks4life Overrun With Chickens

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    @George: I guess we just have different viewpoints on this. I've read that the heritability of resistance to Mareks' is very strong, many vets recommend breeding your own resistant stock as being better than vaccinating for that very reason, hence my belief it's worth doing and easily achievable. Each to their own though.

    Thanks for clarifying the comment about wild birds carrying MDV. I haven't done that much reading up on it, obviously. ;) This thread has probably inspired me to do more reading up on it than I've ever done before, and so much info on it is not couched in definitive terms, just probabilities, which makes it difficult to stand behind any aspect of 'fact' regarding the disease.

    On that topic, though, regarding MDV being only a disease of chickens, from what I've read that is again just a strong probability, not proven beyond a shadow of a doubt.
    Quote: Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC415139/

    Hardly strong wording there, lol!

    I know it can infect quail sometimes, apparently Marek's also occasionally infects geese, egrets, ducks and Great Horned Owls (according to PubMed), and we know it's rapidly adapting, so how do we know for sure it isn't more widely contagious, or won't become so? As with so much else about the disease, the incontrovertible rules are few and far between.
    Quote: (Note: they didn't find MDV in the penguins but didn't rule out the possibility).

    Source: http://www.marineornithology.org/PDF/29_1/29_1_8.pdf

    While reading up on this I also came across info on lions with canine distemper antibodies... Heard about that years ago, since it was on the news, most of you probably heard about it too, but I'd forgotten. Also came across info on quail-chicken hybrids used in studies. Did not know such things existed, or, once again, forgot if I had known before, but as with fertile sheep-goat hybrids, it seems scientists use these 'impossibilities' in studies while the rest of the world remains convinced they are actual impossibilities.

    Some random info:

    Quote: "...However, there are cases of a transfer of virus lineages between distantly related hosts (Ehlers et al., 2007; Ehlers et al., 2008a). Altogether, the phylogenetic data clearly indicate a very narrow host range and specificity of herpesviruses but show at the same time that there is a residual potential to cross host species barriers and to adapt to new hosts (Ehlers et al., 2008b), which raises the question of the present and possibly future zoonotic potential of herpesviruses..."

    "...Zoonoses naturally occur more frequently among closely related host species, but transmissions of disease agents can also be found where barriers of transmission are inherently low or artificially lowered. Examples for such lowering of barriers of transmission are close contacts of humans to animals living in zoos or Safari Parks or situations where pets live in the same household with their owners..."

    "...Yet another alphaherpesvirus, Gallid herpesvirus 2 (GaHV-2, Marek’s disease virus), was claimed to be involved in human infections. First, a connection was postulated in some reports between GaHV-2 infection and multiple sclerosis (McStreet et al., 1992). Another study reported that human serum samples apparently tested GaHV-2-positive by PCR (Laurent et al., 2001). The results, however, could not be reproduced by other research groups and must therefore be deemed inconclusive (Hennig et al., 1998; Hennig et al., 2003). At least, there is no formal proof or even likelihood of an infection of humans with this avian herpesvirus that is capable of infecting host species other than the chicken, namely the turkey and the quail."

    Source:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2815145/

    Some info on Marek's which may or may not have new info for some people:
    Quote: http://www.veterinaryresearch.org/content/45/1/36

    (Note: this last link here is a good, more thorough read-up than you can get in most other places)

    Some more info on Marek's... Now THIS is a concern to me. I have people with multiple autoimmune diseases in my family and I did not know we could develop antibodies to these diseases, since I thought there would not be a reason for that...
    Quote: Author information ► Copyright and License information ►
    This article has been cited by other articles in PMC.
    Abstract

    OBJECTIVES: To compare the prevalence of antibodies against Marek's disease herpes virus (MDV) and against avian leukosis viruses type C (ALV) in groups of workers exposed to poultry and in unexposed groups.

    METHODS: Antibodies directed against avian viral proteins were detected by enzyme linked immunosorbent assay in 549 subjects. Exposure to chickens was high in two subgroups: farmers on intensive chicken farms and workers at chicken slaughterhouses. One subgroup, traditional farmers on dairy or pig farms with poultry, had moderate exposure to poultry. Another subgroup, farmers and slaughterhouse workers on quail farms, had high exposure to quails. Three subgroups were not exposed to chickens: farmers on dairy or pig farms without poultry, workers at cattle slaughterhouses, and white collar workers.

    Also, MDV antibodies were tested after serum sample adsorption with chicken antigens in 134 serum samples. RESULTS: The prevalence of antibodies against MDV was significantly higher in the exposed subgroups than in unexposed groups (odds ratio (OR) 6.17; 95% confidence interval (95% CI) 3.91-9.75). No association was found between seroprevalence and age.

    However, higher prevalence was found among women and was related to duration of exposure to chickens.

    The concentration of antibodies from a few subjects remained very high after adsorption. Significant differences between the men and women were found for the prevalence of antibodies for ALV but were not related to exposure to chickens.

    CONCLUSIONS: The prevalence of antibodies against MDV was significantly higher among workers exposed to chickens and was related to sex and duration of exposure. The higher prevalence of antibodies against avian oncogenic viruses found among women compared with men may be induced by differences in exposure or by genetic factors. The meaning of these high titres could be related to the presence of MDV in humans. Because the involvement of animal oncogenic viruses in human cancer is indicated by epidemiological and some experimental studies, the integration of viral DNA in human cells needs to be investigated.

    Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1128497/
    Quote: Quote: Interesting that they believe it's a risk, I hadn't heard anything but denials of it being a risk before that.

    Anyway, some random info to look though.

    Best wishes.
     
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  8. JeanR

    JeanR Chillin' With My Peeps

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    Interesting read. Thanks for all information.

    One bit about Marek's Disease often forgotten. Vaccine is made from a Turkey herpes virus, not from the Marek's virus. And it causes chickens to become immune to Marek's (most forms commonly suffered) if vaccinated at hatch. Marek's is world wide and sometimes losses are great. I had never heard of it, never had a bird infected until a "friend" sent me a pullet that started the limping on one leg, then the wing droop on the same side--progression and death. Had a few more infected from time to time,, but did not know what it was until the computer search some years later.

    Another bit of info: . IF YOU KEEP TURKEYS with your chickens, you will not have Marek's Disease in your flock. The Turkeys are not sick, and I have poultry breeder friends who do not keep Turkeys, but collect Turkey poop from their friends, dry it,and sprinkle in the coop litter, even a bit in the poultry feeders~ and they do not ever have Marek's, believe their chickens become immune. I keep bantams and do not have room for Turkeys, so vaccinate every chick. And I do not have friends who have Turkeys and could collect a sack of poop for me to use. Although I have Wild Turkeys on my farm, they are not helpful~

    Breeding for immunity is great, but I keep few birds--and breed Show and breeding birds. How do you know they are immune? And if Marek's appears, I could lose years of breeding successful lines of birds, if the ones that did not inherit immunity were the ones that became infected. Just wouldn't work for me.

    There is a great deal of information, some conflicting, about Marek's on many websites. We just do our best and our own experience is our best guide. Just keep learning......
     
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  9. speckledhen

    speckledhen Intentional Solitude Premium Member

    On the subject of MD being a disease of only (or is it mainly) chickens, if someone depopulated their MD-positive flock, did the usual disinfecting with Virkon, then waited, what do you think the chances are that repopulating with guineas would be a way to never see this disease again? Just thinking here because, way back, I originally wanted guineas and only got chickens because they are not just seasonal layers and they were available before the guineas were.

    I had that thought, that if I had to, I might end up going back to guineas, though we all know even tame guineas like I had years ago are not the same as the personable birds I have now. I've considered having them again when I had room for them, though, but are they resistant to this disease? Dr. Peter Brown once joked, when speaking of disease among guineas, that you couldn't kill a guinea with a .22, LOL.



    chooks4life, not something I'd like to contemplate, Marek's even possibly passing to humans, as if we don't already have enough disease troubles!
     
    Last edited: Oct 5, 2014
  10. Nambroth

    Nambroth Fud Lady

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    There are few things with this disease that are stone cold hard fact, as you are discovering. It's why it's so frustrating for us. Also something to keep in mind is that rational scientists-- true scientists, will not often make resolute statements of 100% confirmation, especially in areas of science that we are still struggling to understand. To do otherwise would go against scientific principles; the need to continue to learn, question, investigate without personal bias. So, to that end, we can take findings as as close to fact as they can get, until the next bout of research can either prove or disprove them.

    While bearing in mind that none of this is perfect 100% for sure, Marek's IS primarily a disease of galliformes. To date it is not known to manifest in passerines. Or psittaiscines, for that matter, which I am very thankful for because I keep parrots and they are very dear to me. This can change, of course, but as we dive deeper and deeper into research into this I caution against jumping at too many ghosts (it will make you crazy!!).


    Turkey Herpesvirus (HVT) is MDV3. This is a genotype of Marek's virus. It does not really make chickens immune when administered-- it introduces this related virus to the chicken's immune system when it is developing, so that the bird may (hopefully) build an immune response to the harmless MDV3 virus, so that if later exposed to MDV1 (Chicken Marek's) it will have a greater chance of causing latency BEFORE lymphomas, ataxia, and other symptoms develop. http://jvi.asm.org/content/75/2/971.full

    Quote: I must caution against making all or nothing statements. It's true that many see what seems to be benefit to keeping poultry like this; as the turkeys shed MDV3 around the chickens, the chickens pick it up and it is constantly (and harmlessly) being introduced to their immune systems. Many believe that this causes a greater immune response if the same chickens are later exposed to MDV1 (what we know as Marek's). It is not a guarantee, though, and one must use care when keeping mixed species for other reasons. It works well for some, and not for others. Some people have problems with blackhead in mixed flocks, others do not. Use of common sense and careful observation when keeping any of these birds is of great benefit!
     

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