I don't mean to derail the thread even more but I figured that I would respond to you, nambroth. Here is one abstract I read:
It deals with revaccination of non-symptomatic birds and one could infer that vaccination of birds which are non-symptomatic, even if they are older and even if they have been exposed to the virus through a maternal source, would have the same or similar results. I know that the vaccine is turkey herpesvirus while the chicken virus is a bit different but I've been vaccinating my older birds (like you sort of hinted around in your article) and it seems to be effective at just about any age. Just HOW effective, I have yet to find out, I guess only time will tell but so far, so good.
Revaccination with Marek's Disease Vaccines Induces Productive Infection and Superior Immunity▿
- Changxin Wu1,5,*,
- Junji Gan1,
- Qiao Jin1,
- Chuangfu Chen2,
- Ping Liang1,
- Yantao Wu1,
- Xuefen Liu1,
- Li Ma4 and
- Fred Davison3
+ Author Affiliations
- 1Laboratory of Animal Infectious Diseases of Agricultural Ministry of China, Yangzhou University, Yangzhou 225009, China
- 2Department of Veterinary Medicine, Shihezi University, Shihezi 832003, China
- 3Laboratory of Avian Immunology, Institute for Animal Health, Compton RG20 7NN, United Kingdom
- 4Research Centre, Northern Jiangsu Hospital, Yangzhou 225009, China
- 5Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, United Kingdom
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ABSTRACT
The most common lymphoproliferative disease in chickens is Marek's disease (MD), which is caused by the oncogenic herpesvirus Marek's disease virus (MDV). The emergence of hypervirulent pathotypes of MDV has led to vaccine failures, which have become common and which have resulted in serious economic losses in some countries, and a revaccination strategy has been introduced in practice. The mechanism by which revaccination invokes superior immunity against MD is unknown. After field trials which showed that revaccination provided protection superior to that provided by a single vaccination were performed, experiments were conducted to explore the interaction between revaccinated chickens and MDV. The results showed that the chickens in the revaccination groups experienced two consecutive productive infections but that the chickens in the single-vaccination groups experienced one productive infection, demonstrating that revaccination of viruses caused the chickens to have productive and then latent infections. Revaccination of the virus induced in the chickens a higher and a longer temporary expansion of the CD8+, CD4+, and CD3+ T-lymphocyte subpopulations, stronger peripheral blood lymphocyte proliferative activity; and higher levels of neutralizing antibody than single vaccination. These findings disagree with the postulate that MDV antigens persist, stimulate the immune system, and maintain a high level immunity after vaccination. The suppression of productive infection by maternal antibodies in chickens receiving the primary vaccination and a lower level of productive infection in the revaccination groups challenged with MDV were observed. The information obtained in this study suggests that the productive infection with revaccinated MDV in chickens plays a crucial role in the induction of superior immunity. This finding may be exploited for the development of a novel MD vaccine that results in the persistence of the antigen supply and that maintains a high level of immunity and may also have implications for other viral oncogenic diseases in humans and animals.
I have no idea where I came up with the idea of vaccinating a symptomatic bird. I need to start bookmarking the abstracts and articles that I read, but I'm usually looking for answers to something else and only find them interesting but not pertinent so I dont think ahead for the moment when they become pertinent later and by then I've lost them. So without a supporting argument I have to say that vaccinating a bird that is already symptomatic should be avoided. But if the other birds were not vaccinated, I would still say that they could be vaccinated.
I do have my Mareks shipped ground. I wait until the weather is cool but not freezing and then I stock up, so its only about $25 per vial. I feel confident doing it this way because I inadvertently left a vial of the vaccine out for a couple of weeks before I used it and then I re-read the part about keeping it in the fridge. Thought I had killed all of my chicks but it was still an effective vaccine, so now I go ground. (I live in an epidemic area so I would know with certainty if the vaccine had lost effectiveness) But I do keep it in the fridge once I get it- I will only tempt the hand of fate so much.
Also, I use u100's which are only $2 per bag of 10 from CVS so it makes it totally affordable.
I know, I'm bucking convention but it works so I go with it.
But I digress- sorry.
I do hope it isn't Mareks though and I guess I glossed over the part where she started showing symptoms at 2 weeks- I had the nine week figure in my head from the title. However while it is true that most cases don't show up until week 5, I have heard that in severe cases it can show up a little earlier, but two weeks does sound too early, so that would be good news- right?.
You were talking about fats and we've all been talking about B vitamin deficiencies but Vitamin E is one of the fat soluble vitamins and vitamin E and selenium have this mysterious relationship with neurological/muscular/skeletal development and health. If she isn't getting good fats and she has a malabsorbtion issue, maybe its just a vita E and selenium deficiency in both birds. Could be a deficiency which started in the hen that laid the eggs they hatched from.