Research renders good news about Marek's Disease

USPOULTRY and the USPOULTRY Foundation have announced the completion of a funded research project at the USDA Agriculture Research Service in East Lansing, MI, in which researchers found that the virulence of Marek’s disease virus may have plateaued. The project is part of the Association’s comprehensive research program encompassing all phases of poultry and egg production and processing. A brief summary of the completed project is shown below.
The project summary is as follows:
Project #F051: Pathotyping of Current Marek’s Disease Virus Field Strains and Identification of Sequence Variants to Predict Virulence
(Dr. John Dunn and Dr. Hans Cheng, Avian Disease and Oncology Laboratory, USDA Agricultural Research Service, East Lansing)
Researchers at the USDA Avian Disease and Oncology Laboratory recently completed a project that focused on the continued evolution of Marek’s disease virus (MDV). The disease causes tumors in chickens, has a long history of continuous evolution toward increased virulence in the field, which has required the continued development of more effective vaccines.
Dr. Dunn has completed the first survey of current MDV field viruses since 1997 and found, surprisingly, that the virulence of MDV in the U.S. poultry industry may have plateaued. He was not able to find MDV from current field cases that were any more virulent than viruses from 20 years ago. This is good news for the industry and may indicate that current management and vaccine programs have had a big positive impact.A complete report, along with information on other Association research, may be obtained by going to USPOULTRY’s website, www.uspoultry.org.

Marek’s disease control still a challenge for poultry industry

The development of the first Marek's disease vaccine in the late 1960's was a major accomplishment in the history of animal health, according to Dr. Isabel Gimeno, associate professor, College of Veterinary Medicine, North Carolina State University. She told the audience at the "Managing Marek's disease for your most valued birds" webinar, sponsored by Zoetis and presented by WATT Global Media on December 18, 2013, that the original Marek's vaccine was the first successful vaccine for a tumor-causing disease.
Gimeno, whose primary research interest is Marek's disease, said that the Marek's disease virus has evolved over time, and it will continue to present a challenge for poultry producers. She said that the original HVT vaccine for Marek's disease was effective from its introduction in 1969 until the 1980s, when it was replaced with bivalent vaccines, which were replaced themselves in the 1990s with the Rispens vaccines. The Maerek's disease viruses in the field continue to evolve and become more virulent, she said.
Vaccination tips
Management and correct use of vaccines are critical for protecting against the Marek's disease virus, according to Gimeno. She said that in ovo vaccination provides better protection against the Marek's virus for the bird than does subcutaneous vaccination. For farms that have a severe Marek's challenge, she recommended in ovo vaccination with HVT followed by day-of-age vaccination with a Rispens vaccine. She cautioned that, in all cases, it is important to administer the full dose of vaccine to all birds.
High challenge situations
Dr. Kalen Cookson, director of clinical research,  Zoetis, said that Marek's disease related mortality is just the "tip of the iceberg" when evaluating the true cost of the disease. He said that the immune suppression that non-fatal Marek's infections can cause is a major threat for flocks.
Cookson said that on farms with a strong Marek's disease virus challenge from a particularly virulent strain, using a Rispens vaccine gives significantly better protection than do conventional bivalent vaccines in both broilers and breeders and table egg layers. He said that Low-passaged "European" Rispens CVI-988 gives the greatest margin of efficacy in high challenge situations.
View the on-demand webinar here. 

Register for free webinar on managing Marek’s disease

Register for the free webinar, Managing Marek's disease for your most valued birds, which will be held Wednesday, December 18 at 9 a.m. CT.
Marek's disease is one of the most important poultry diseases that has a significant economic impact in poultry operations with losses exceeding US$1 billion annually. Recent outbreaks demonstrate the continued evolution of virulent strains in different parts of the world. Learn more about best practices to protect your operation against these virulent strains and improve the profitability of your operation.
What you'll learn:

• Insights behind recent Marek's disease outbreaks
• Differences in protection among Marek's disease vaccines based on level of passages
• Best practices for protecting against virulent strains of Marek's disease
• Best practices for monitoring Marek's disease vaccination programs
The speakers for this webinar are Dr. Kalen Cookson, senior technical services veterinarian, Zoetis; and Dr. Isabel Gimeno, associate professor, Poultry Health Management, North Carolina State University.
This webinar is sponsored by Zoetis and presented by WATT Global Media.

Ceva combines poultry vaccines into single dose against three diseases

Ceva has combined two of its poultry vaccines into a single dose that will protect against Newcastle, Gumboro and Marek’s disease.
The company's Gumboro vaccine, Transmune IBD, and its Newcastle Disease vector vaccine, Vectormune ND (which also protects against Marek's Disease), can be mixed in diluent with a blue vaccine tracer and administered in the hatchery, either in ovo or subcutaneously at one day old, according to Ceva. "Vaccinating chicks against Gumboro and Newcastle disease has always been difficult for broiler producers because of the uncertainty around what day to administer," said Ceva.
The two vaccines used to come in packages in different sizes, but the company has standardized the packaging for ease of use. Transmune IBD and Vectormune ND are now available in uniform 1,000-, 2,000- and 4,000-dose vials.

Poultry genetic markers potential tools in controlling Marek's disease

A new strategy for controlling Marek's disease in poultry is to develop a line of chickens which are genetically resistant to the effects of the virus, and genetic markers may be a tool in controlling the virus, according to research completed by the U.S. Poultry & Egg Association and the U.S. Department of Agriculture's Agricultural Research Service Avian Disease and Oncology Laboratory.
The disease is currently controlled by routine vaccination of commercial broilers, breeders and layer chickens, but because the Marek's disease viruses are constantly evolving, new vaccines need to be continually developed to control bird losses. Research was conducted to: identify single nucleotide polymorphisms (structural units of DNA) in susceptible chicken lines which are associated with Marek's disease susceptibility, and identify alternative units conferring resistance. A total of 57,636 single nucleotide polymorphisms were screened and 172 units located on chromosomes 1, 3, 15 and Z were found to be possibly associated with the disease.
One of the 172 single nucleotide polymorphisms was identified at the same gene location as the susceptible allele and as the resistant allele. These results suggest eliminating a susceptible gene in breeding programs may be helpful in the control of Marek’s disease. According to researchers, primary breeding companies may use this new research to genetically select commercial chicken lines with enhanced resistance to Marek's disease.

Dr. Karel Schat wins lifetime achievement award for poultry health contributions

Dr. Karel Schat of the Cornell University College of Veterinary Medicine was presented with a lifetime achievement award "in recognition of outstanding research and contributions to poultry health" at the 5th International Workshop on the Molecular Pathogenesis of Marek's Disease Virus.
The award, Schat's fifth relating to his work in poultry health, is meant to honor all his accomplishments in the field, including his work on Marek's disease. “This award is a fitting capstone to [Schat's] scientific career,” said Dr. Avery August, chair of the Department of Microbiology and Immunology to which Schat belongs. “I believe that it illustrates the esteem with which his colleagues view him and his work in avian health research, particularly his work on Marek’s disease."
Schat's other awards include the Beecham Award for Research Excellence, the Upjohn Achievement Award for distinguished contributions in avian medicine, the Bart Rispens Research Award in recognition of an outstanding research contribution in the field of avian pathology, the Pfizer Award for Excellence in Poultry Research and the Merck Award for Achievement in Poultry Science.

Budget cuts impact avian lab

The USDA-ARS Avian Disease and Oncology Laboratory in East Lansing, Mich., is experiencing difficulty in operations. The laboratory, which among other achievements was instrumental in developing the original HVT vaccine for Marek’s disease, has been subjected to successive USDA budget cuts and threats of closure.
The staff of the lab include highly trained scientists with specific expertise in leukosis and Marek’s, in addition to new molecular biological techniques for diagnosis and prevention of disease. Recently, two projects have been funded by Congress including an in-depth study of the mechanisms of action for Marek’s disease and avian leukosis viruses and a project on genomics and immunology of chickens.
Research conducted at the ADOL could shortly result in the release of a new recombinant vaccine against Marek’s disease. It is generally acknowledged that new vaccine strains lose effectiveness after 10 to 15 years.

Merial is exclusive distributor for AviTech's in ovo injection systems

Merial Limited has become the the exclusive distributor and technical service provider of the in ovo injection systems of AviTech, LLC.
As a result, Merial offers poultry customers worldwide its portfolio of avian vaccines together with in ovo technology. Merial produces vaccines for the treatment of Marek’s Disease and Infectious Bursal Disease, that are especially suitable for in ovo administration. The company supports its vaccine operations through the development and service of administration devices, and these activities are now complemented by its exclusive distribution of AviTech’s IntelliJect and ManualJect in ovo injection systems, Merial said in a press release.
“Merial has long recognized the value of working with the industry to make our products available conveniently and efficiently. The in ovo route is becoming ever more important, and we are delighted to partner with AviTech,” said Merial’s Global Head of Avian, Alain Wille.
AviTech is a poultry equipment manufacturer that provides engineered solutions for the poultry industry. The company’s leading equipment line consists of the IntelliJect and ManualJect systems.Merial is one of the largest global avian vaccines companies, providing a comprehensive range of products.
Merial operates in more than 150 countries worldwide.