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Online Discussion: Tracking new emerging diseases and the next pandemic

Don’t chicken out on chicken

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3) exposure of the general population, from inoculation with vaccines prepared from chicken embryo cells contaminated with these viruses;
 
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HOW SAFE ARE EGGS .... USED FOR VACCINES
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Title: OCCURRENCE OF AVIAN LEUKOSIS VIRUS SUBGROUP J IN COMMERCIAL LAYER FLOCKS IN CHINA

Authors
item Xu, B - CHINA AGRIC UNIV BEIJING
item Dong, W - CHINA AGRIC UNIV BEIJING
item Yu, C - CHINA AGRIC UNIV BEIJING
item He, Z - CHINA AGRIC UNIV BEIJING
item Lv, Y - CHINA AGRIC UNIV BEIJING
item Sun, Y - CHINA AGRIC UNIV BEIJING
item Feng, X - CHINA AGRIC UNIV BEIJING
item Li, N - CHINA AGRIC UNIV BEIJING
item Lee, Lucy

<> Submitted to: Avian Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 15, 2003
Publication Date:
February 1, 2004
Citation:
Xu, B., Dong, W., Yu, C., He, Z., Lv, Y., Sun, Y., Feng, X., Li, N., Lee, L.F. 2004. Occurrence of avian leukosis virus subgroup J in commercial layer flocks in china. Avian Pathology. 33(1):13-17.

Interpretive Summary: Subgroup J avian leucosis virus (ALV-J)
 
is an emerging economically important virus infection that can cause cancer-like disease and other production problems in meat-type chickens. The virus was first reported in 1991 in the United Kingdom and in 1993 in the United States in meat-type of chickens.
 
This paper describes the identification of myeloid leucosis in egg layer chickens in China. Immunohistochemical studies with monoclonal antibody against envelope glycoprotein gp85 of ALV-J revealed antigen in all organs examined. This is the first report of field cases of myeloid leucosis caused by ALV-J in commercial egg-type chickens. This new information is significant and useful to scientists in academia and industry who are studying the epidemiology and control of this important virus infection of chickens.

Technical Abstract: Mortality from myeloid leukosis was observed in commercial layers from 12 farms in northern China. Affected chickens were extremely thin and dehydrated, bleeding occurred in feather follicles and claws, combs were pale and anaemic, phalanges were swollen, and many yellowish-white tumours were seen on the visceral surface of the sternum. Focal tumour cells, with spherical eosinophilic granules in the cytoplasm, were found in the liver, spleen, kidney, ovary, oviduct, lung, bone marrow, proventriculus and gut by histopathological examination. Immunohistochemical studies with a monoclonal antibody to gp85 of avian leukosis virus subgroup J (ALV-J) revealed antigen in all organs examined. Polymerase chain reaction tests using a pair of ALV-J-specific primers H5/H7 (Smith et al., 1998) produced a 545 basepair fragment. The sequence of the Polymerase chain reaction product was compared with that of the ALV-J HPRS-103 prototype strain. The identity of nucleotides and predicted amino acids was 97.4% and 96.1%, respectively. On this basis the disease in the egg-type chickens was diagnosed as an ALV-J infection.

 
This is the first report of field cases of myeloid leukosis caused by ALV-J in commercial egg-type chickens.

 
 
 
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Title: ISOLATION OF SUBGROUP A AVIAN LEUKOSIS VIRUS FROM COMMERCIAL MAREK'S DISEASE VACCINES

Authors

<> Submitted to: International Marek's Disease Symposium Abstracts and Proceedings
Publication Type: Abstract
Publication Acceptance Date: July 14, 2004
Publication Date: July 14, 2004
Citation: Fadly, A.M., Silva, R.F., Hunt, H.D. 2004. Isolation of subgroup A avian leukosis virus from commercial Marek's disease vaccines [abstract]. International Marek's Disease Symposium Abstracts and Proceedings. Paper No. P.8.

Technical Abstract: Commercial Marek's disease (MD) vaccines were submitted to USDA-ARS Avian Disease and Oncology Laboratory for testing for possible contamination with
 
 avian leukosis virus (ALV).
 
Samples of MD vaccines manufactured by two different companies (A & B) were received from a breeder company; samples were also received directly from vaccine company B. Initially, samples tested positive by virus isolation for subgroup E (endogenous) ALV. However, upon re-passage, the vaccines also tested positive for exogenous (subgroup A) ALV. PCR and DNA sequencing of the envelope of isolated ALVs confirmed the results obtained from virus isolation assays that in addition to endogenous subgroup E ALV, an exogenous subgroup A ALV was also present in the vaccines tested. Although the source of this contamination of MD vaccines with exogenous subgroup A ALV has not be determined, the data presented in this paper should be of interest to vaccine manufacturers, suppliers of specific-pathogen-free (SPF) eggs as well as scientists from academia and government.

http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/61030000.htm

Name, Synonyms and Lineage

Synonym(s): "Avian type C retroviruses". Virus is assigned to the subfamily 00.061.1. Orthoretrovirinae ; assigned to the family 00.061. Retroviridae .

Taxonomic Proposals and Changes

A taxonomic proposal has been submitted to the ICTV by the Vertebrate Virus Subcommittee Study Group for Retroviridae at the meeting in San Diego, March 1998, to change the name from
 
"Avian type C retroviruses" to Alpharetrovirus.
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wikipedia....

A gammaretrovirus is a genus of the retroviridae family. Many species contain

 

Examples are the murine leukemia virus, the feline leukemia virus, the feline sarcoma virus, and the avian reticuloendotheliosis viruses.

 
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Reticuloendotheliosis viruses have been shown to be causative of
 
tumors in a variety of avian species.
 
The major structural protein of these non-genetically transmitted viruses is demonstrated to possess antigenic determinants common to those of all known mammalian type C viruses.
 
 These findings establish a mammalian origin for this oncogenic avian retrovirus group.
 
None of the known mammalian type C virus groups demonstrated a closer immunological relationship to avian reticuloendotheliosis viruses.
 
These results suggest that reticuloendotheliosis viruses have been non-genetically transmitted for a long period of evolution or that these viruses may have arisen by relatively recent infection of birds with an as yet undiscovered mammalian type C retrovirus.
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Excerpt....
 
Vaccines effectively reduce and prevent death and disease from many viral infections. However,
 
 vaccine production occasionally has been complicated by inadvertent contamination with adventitious agents that may have originated from cell substrates used to propagate vaccine strains.
 
Examples of such contamination include
 
simian virus in early polio vaccines grown on monkey kidney cells and avian leukosis virus (ALV) in yellow fever vaccines propagated in chick embryos (1). Hepatitis B virus has also been identified in yellow fever vaccines produced by using pooled human serum as a stabilizing agent
 
(2). Exposure of vaccine recipients to contaminated vaccines has been associated with effects ranging from benign to demonstrable transmission of infection, with or without subsequent disease (2,3).

Reverse transcriptase (RT) activity, an indicator of retroviruses, has recently been detected by sensitive polymerase chain reaction (PCR)-based RT assays in currently used vaccines produced in chick embryo fibroblasts or embryonated eggs (4-7).

The RT-positive vaccines include measles, mumps, and yellow fever vaccines produced by several manufacturers in Europe and the United States (4,5).
 
RT activity was detected in the vaccines despite strict manufacturing practices requiring that chick embryos and embryo fibroblasts be derived from closed, specific-pathogen-free chicken flocks.
 
Such chickens are screened for known pathogens, including two exogenous
 
avian retroviruses:
 
 reticuloendotheliosis virus
 
and ALV (8). 
 
 (AVIAN LEUKOSIS VIRUS)
 
 
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wikipedia...
 
Retrovirus
 
Retroviruses are RNA-containing viruses that use the enzyme reverse transcriptase to copy their RNA into the DNA of a host cell. Retroviruses have been isolated from a variety of vertebrate species, including humans, other mammals, reptiles, and fish. The
 
family
Retroviridae
includes such important human pathogens as human immunodeficiency virus (HIV) and human Tlymphotropic virus (HTLV),
 
the causes of AIDS and adult T-cell leukemia respectively.
 
 
The study of this virus family has led to the discovery of oncogenes,
 
 resulting in a quantum advance in the field of cancer genetics. Retro-viruses are also valuable research tools in molecular biology and gene therapy.
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Retrovirus
 
The virus itself stores its nucleic acid genome and serves as a means of delivery of that genome into cells it targets as an obligate parasite, and constitute the infection.
 
Once in the host's cell, the RNA strands undergo reverse transcription in the cytosol and are integrated into the host's genome, at which point the retroviral DNA is referred to as a provirus.
 
 
 
 
A provirus is a virus that has integrated itself into the DNA of a host cell.
 
One kind of virus that can become a provirus is a retrovirus.
 
When a retrovirus invades a cell, the RNA of the retrovirus is transcribed into DNA by reverse transcriptase, then inserted into the host genome by an integrase.
 
A provirus is not active while integrated into a host genome in this way. Instead, it is passively replicated along with the host genome and passed on to the original cell's offspring;
 
all descendants of the infected cell will also bear proviruses in their genomes.
 
Eventually, in response to changes in the host's environmental conditions or health, the provirus will be activated and begin massive transcription of its viral genome.
 
This results in the destruction of its host as its protein synthesis machinery is hijacked to produce more viruses.
 
Examples in humans include HIV and HTLV.
...................................
wikipedia...
 
A gammaretrovirus is a genus of the retroviridae family.
Many species contain ....*oncogenes..... and cause sarcomas and leukemias.
 
Examples are the
 
murine leukemia virus,
 
the feline leukemia virus,
 
the feline sarcoma virus, and the
 
avian reticuloendotheliosis viruses.
 

An *oncogene
 
is a modified gene, or a set of nucleotides that codes for a protein,
 
that increases the malignancy of a tumor cell.
 
Some oncogenes, usually involved in early stages of cancer development, increase the chance that a normal cell develops into a tumor cell, possibly resulting in cancer.
 
New research indicates that small RNAs 21-25 nucleotides in length called miRNAs can control expression of these genes by downregulating them.
 
 
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Please see this...
 
photos etc... AVIAN CHOLERA
 
 
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Please see this...

photos etc... AVIAN CHOLERA

http://www.nwhc.usgs.gov/publications/field_manual/chapter_7.pdf
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why wasnt mine clickable?

it was a copy and paste of the previous post?
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hi...Kilt.
 
yes..   right.   in order to click on it ... go to the source page and
copy/paste from the address bar.
 
(all note... pictures graphic)
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 "Avian influenza is a disease that affects all poultry. It doesn't recognise any differences between free-range, organic or conventional types of production. The virus will freely attack any sort of poultry, however it is kept. When we had low-pathogenic avian influenza back in the spring that occurred on two free-range farms and then went into a broiler breeder unit and we understood it was by fox carriage."

Could avian flu spell end free range eggs?

By Julia Stuart

Published: 08 February 2007

Peter Barton is as uneasy as the rest of them. The organic poultry farmer has 50,000 hens scuttling around his fields in East Sussex. He, like many farmers, thought if anyone was going to be hit by bird flu, it would be someone like him. "We are obviously very concerned about what has happened, but it's not a total surprise," he says. "We've been expecting this for the last two or three years. However, I am very surprised how it turned up on an intensive farm rather than on one of ours. They are able to have much higher biosecurity. Our birds just run around and come into close contact with all things wild and natural. It flies in the face of logic. Something has gone wrong somewhere."

Thankfully Grassington Farm near Lewes, which produces organic chicken eggs and pullets, is a long way from the turkey farm in Holton, Suffolk, where Britain's first case of the H5N1 strain of bird flu broke out last week, killing 2,600 turkeys and leading to the slaughter of 159,000 more. But there are about 62 free-range or organic farms in the controlled zone around Holton. Defra requires farmers to house their poultry or isolate them from wild birds, by, for example, netting them, and feeding them and watering them indoors where possible. Organic and free-range farmers throughout the country are being urged to maintain high levels of biosecurity and develop plans to enable them to bring their birds inside if required.

"A high standard of biosecurity, separation of poultry from wild birds and careful surveillance for signs of disease remain the most effective means of protection," says a Defra spokesman. "We do not intend to permit the vaccination of birds as an immediate disease control response."

Peter Barton has the facilities to keep his birds inside, not that he wants to. "To protect them we would have to [bring them inside] if Defra advised us to," he says. "At the moment they haven't, but that could change soon. We have to protect the welfare of the birds, and our staff. We all live and work on the farm, so we live cheek-by-jowl with our birds."

The Food Standards Agency has already received calls from worried members of the public concerned about the safety of eating poultry. Barton believes that the current scare might work in the favour of organic farmers. "If anything, in situations like this the consumer tends to move towards extensive systems rather than intensive systems. [Scares] can be a bit of good news for the smaller farmer."

Robin Maynard, campaigns director for the Soil Association, is relieved that the outbreak wasn't at an organic or free-range farm. He claims that some in the intensive poultry industry had predicted that such farmers would be responsible for bringing bird flu into Britain.

"We are very keen that the public still supports organic and free-range. It's one of the success stories in farming," he says. "People are surprised to learn that 8,000 turkeys were kept in one shed and they've had to slaughter 160,000 overnight. That is why turkey is so cheap. But the turkeys live much shorter lives, they don't get fed the type of food that organic and free-range birds get and they are kept in pretty inhumane conditions. That's why organic and free-range turkey costs more, tastes a lot better and you can eat it with a clear conscience. What we don't want to see is the industry wiped out by unfortunate incidents such as this."

He claims there is "interesting evidence" to suggest that organic and free-range poultry may have naturally stronger immune systems than those reared intensively. "The whole principal of organic farming is built on positive health and naturally immune livestock poultry. One of the examples that supports this is the fact that there was an outbreak of a different strain of bird flu, H7, in Norfolk last year. It was identified in an intensive indoor broiler flock and there was a high mortality rate. About 15 days later a vet from a nearby free-range unit rang up and said he thought they may have had it first. There had been a much lower mortality rate. Defra vets confirmed it was H7 and that it had broken out there first. But because the birds weren't packed so closely together and were going outdoors they hadn't died off so much or spread the disease so quickly."

The farm animal welfare organisation Compassion In World Farming (CIWF) has no qualms in blaming factory farming for what it calls "the myth" that wild birds have caused the current bird-flu crisis. "Factory farming was always bound to cause a disease backlash by pushing nature way beyond its limits," says CIWF's chief executive, Philip Lymbery. "Keeping massive numbers of poultry on intensive farms worldwide is now coming back to bite us in the form of avian influenza."

Intensively farmed poultry is often kept in overcrowded conditions that provide an ideal breeding ground for disease, the charity claims. The chronic stress to which the birds are subjected could also weaken their immune systems.

However, the British Poultry Council denies that factory farming is to blame. "I think that would be pure speculation," says a spokesman. "The most predictable way of avian influenza spreading remains via wild birds, and I don't think the question of intensive farming is something that should be considered in the spread of bird flu."

Neither does the NFU agree with Philip Lymbery. Maria Ball, the union's chief poultry adviser, says: "I don't know where the science is in his statement and I would not support that view at all." Blaming one part of the industry is "irresponsible", she adds. "Avian influenza is a disease that affects all poultry. It doesn't recognise any differences between free-range, organic or conventional types of production. The virus will freely attack any sort of poultry, however it is kept. When we had low-pathogenic avian influenza back in the spring that occurred on two free-range farms and then went into a broiler breeder unit and we understood it was by fox carriage."

Peter Barton, meanwhile, refuses to worry about the future. "Our birds are pretty robust," he says. "That doesn't mean that they won't get the disease if it becomes endemic. At the moment it just seems to be a breakdown somewhere along the line. What we would be concerned about is if large numbers of wild birds were found to be dead or dying, which would indicate that the disease has spread into the country. There is no evidence of that at the moment, thank goodness."

What is free-range?

* To qualify as free-range, the birds must have access to at least an acre of land for every 400 birds.

* To be certified organic, the birds must be free-range and fed on a diet produced without artificial fertilisers and pesticides. The use of medicines is restricted and flock sizes are smaller.

* In factory farms, birds are fed antibiotics to help prevent disease spreading.

* Free-range flocks are more vulnerable to exposure to avian flu through contact with wild birds. But free-range farmers argue that intensive farming helps to spread disease and that their birds have a stronger immune system and more resistance to infection.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote kparcell Quote  Post ReplyReply Direct Link To This Post Posted: February 20 2007 at 11:27am
O.k., the verdict is in, but does it have teeth?

Factory Farming is greatest source of bird flu pandemic threat, so if the factories shut down now then many millions of lives could be saved.
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kparcell  hi ,                after I read your post here and then in the news , I wandered over to the http://www.thepoultrysite.com/search/index.php?cat=0&q=vaccines+&x=10&y=14  I read and I read and I sooo agree with you . Spent a while on the diseases of chicken page . Hours http://www.thepoultrysite.com/diseaseinfo  then followed on to what vaccinations chickens have  here http://www.thepoultrysite.com/articles/377/small-flock-vaccination  just can't understand what gets folk excited about eating chickens now .......then remembering great info post from AnnHarra noticed this here . http://www.thepoultrysite.com/focus/scheringplough-animal-health/36/mycoplasma-vaccines-for-chickens-f-vaxmg   ahhhhh.....
 
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