**UNITED STATES DEPARTMENT OF AGRICULTURE ANIMAL AND PLANT HEALTH INSPECTION SERVICE** 

**VETERINARY SERVICES THE**  **CEN TER FOR VETERINARY B**  **IOLOGICS**



# Environmental Assessment **For Field Testing of a Marek’s Disease** 
**– Newcastle Disease**  **Vaccine ,**  **Serotype 3, Live**  **Marek’s Disease Vector**

Octob er 201 4 Prepared by: United States Department of Agriculture Animal and Plant Health Inspection Service

Veterinary Services The Center for Veterinary Biologics

_________________________________________________________________________________________________ Environmental Assessment Field Trial of an Experimental MD

– ND Vaccine, Seroty pe 3, L ive MD V ector**Environmental Assessment f**  **or Fi**  **eld Testing of a**  **Marek’s Disease**
**– Newcastle Disease Vaccine, Serotype 3, Live**  **Marek’s Disease Vector I**  . **Proposed Action** APHI S is considering granting authorization to ship an unlicensed Marek’s Disease

– Newcastle Disease Vaccine, Serotype 3, Live Marek’s Disease Vector, for field safety testing in chickens . Merial , In c., Athens, Georgia, has requested authorization to conduct the field tests under conditions of husbandry that are ty

pical of the commercial poultry industry in the United States. The vaccine is intended for use in healthy 18 - day - old or older embryonate d eggs or day - old chickens as an aid in the prevention of Marek’s disease and Newcastle disease. Under the provisions of the Virus - Serum - Toxin Act of 1913, as amended in 1985, the USDA must ensure that veterinary biologics are pure, safe, potent, and effi cacious and not worthless, contaminated, dangerous, or h armful. Accordingl y, APHIS has conducted a risk anal ys is and has concluded that, regarding in ovo or subcutaneous administration of this single - dose vaccine in embryonated eggs or chickens , the safety risks to animals, public health, and the environment are low. A copy of the firm’s risk analy sis with confidential business information re dact ed is available online in the Federal Register docket and b y request, as indicated in the Federal Regi ster Notice announcing the proposed field testing . APHI S considers the firm’s risk anal ys is, o ther studies and tests conducted b y the firm, the confirmatory testing completed by APHI S personnel on the Master Seed to confirm the vaccine’s purity, sterility , identity , and expression of immunogenic protein, and the results of literary and regulatory

review regarding this and similar previously

tested or licensed products. Based on APHI S ’ anal ys is of the relevant data, a preliminary determination has been re ached that field testing this veterinary vaccine will not have a significant impact on the quality of the human environment and that an environmental impact statement need not be prepared. We intend to authorize shipment of this vaccine for field testing following the close of the comment period of the Federal Register N otice announcing the pending trial unless new substantial issues bearing on the effects of this action are brought to our attention. **II. Background**  Marek’s disease virus (MDV) is found in chicken flocks worldwide. Virtually all flocks, except those kept under pathogen - free conditions, can be consider ed to be infected. This infection may

manifest itself as clinical disease consisting of depression, ataxia, enlarged nerves, and death, or as a subclinical decrease in egg production and growth rate. 1 Newcastle disease virus (NDV) can be neurotropic and/or viscerotropic, affecting the respiratory , nervous, and digestive s ys tems. NDV occurs in man y species of birds, is transmitted by

inhalatio n and ingestion, and display s wide variation in pathogenicityamong strains. NDV strains are classified as as ymptomatic, lentogenic (mildly virulent), mesogenic (moderatel y virulent), and velogenic (highl y virulent). Respiratory signs are most common in lo w virulence infections. Nervous signs usually follow but may occur simultaneously

with the respiratory

signs in neurotropic velogenic disease. Respiratory signs with depression, diarrhea, and swelling of the head and neck are common to the most virulent fo rm of NDV (viscerotropic velogenic Newcastle disease or VVND), but nervous signs may

be seen as well. 2 For both MDV and NDV, vaccination is the principal method of control for the strains common to the United States. The herpesvirus of turkeys (HVT), an avirulent strain related to MDV, has been widel y used commercially

as a heterot ypic vaccine against MDV. 1 HVT, classified as MDV seroty pe 3, is not pathogenic in chickens and has minimal risk of environmental dispersal, less so than the MDV strains of s erotyp es 1 and 2. The experimental vaccine to be used in the proposed field trials is a live virus consisting of the HVT backbone express ing an immunogenic protein from NDV . Several recombinant HVT vaccines have been used in recent ye ars featuring the inse rtion of genes from other poultry viruses including NDV, infectious bursal disease virus, and infectious lary ngotracheitis virus . The proposed field safety test will be conducted in at least three different geographical locations . T he product will be use d according to instructions on the product circular , and in accordance with standard requirements published in Title 9, Code of Federal Regulations ( 9 CFR), Part 103.3, concerning shipment of experimental biological products for use in animals. 3 The pote ntial for escape and dispersal of the experimental vaccine from the proposed release sites is low. The personnel to conduct the study are experienced in commercial po ultry health management. **III. Need for the Proposed Action**  MDV is a ubiquitous and economicall y important cause of neoplasm in poultry. The advent of vaccination has dramaticall y reduced losses due to MDV in broiler and layer flocks. However, disease can become a serious problem in individual flocks or certain geographic areas, most like ly due to earl y exposure to virulent virus strains. Protection against NDV generall y requires repeated vaccination throughout life, the frequency depending on the level of exposure. This recombinant vaccine represents an attempt by Merial, Inc., to produce an efficacious and safe vaccine against MDV and NDV that protects chicks earl y in life with one vaccination. **IV. Areas of Concerns**  The three areas of concern to APHI S are: 1) animal safety, 2) public health , and 3) environmental safety . APHI S has conducted its own risk anal ys is to assess whether risks are associated with the proposal to field t est this experimental vaccine. The safetycharacteristics of th e vaccine h ave been thoroughly evaluated. The conclusions derived from the risk anal ys is for each of the areas of concern are summarized below. **A. Animal Safety**  The risk to animals is low.  The HVT backbone of the vaccine is well - characterized and has been safely used previously

in numerous licensed vaccines. The NDV gene insert is th e same as that expressed without issue in a licensed recombinant NDV - fowl pox vectored vaccine , licensed in 1995. 4 The NDV - HVT vectored vaccine has similar attenuated characteristics as those of the parental HVT, as demonstrated in shed/spread and tissue tropism studies conducted by the firm.  In a reversion to virulence study in chickens conducted according to Veterinary Services Memorandum 800.201, following five passes in one - day- old chickens, no lesions were observed in any of the birds at seven weeks pos t - inoculation. Virus was recovered from all passages, but no virus was recovered from contact controls. There was no loss of expression of the NDV gene after the five passes.  Non - target animals: A safety study in mice indicated no virus recovery after subc utaneous injection and epidermal scarification of 15 mice. The safety study in non - target avian species consisted of groups of 40 quail, turkey s, ducks, pheasants, and pigeons that received 10x doses of the vaccine either in ovo or subcutaneous ly . T he groups were observed for 120 day s until necrops y. No MDV clinical signs or lesions were seen.  Target animals: A safet y study was conducted in chickens per 9 CFR , Part 113.330, using a 10x dose for the subcutaneous route in day- old chicks and the in ovo route for 18 - day - old embryos. The chickens were observed for 120 days , then weighed, euthanized, and necropsied. No MDV lesions and no weight loss, when compared to sham - inoculated controls, were detected .  Chicks vaccinated b y the subcutaneous route and chick s hatched from embryos vaccinated in ovo were challenged at 28 day s with NDV or MDV and were protected against disease . **B. Public Health**  The risk to public health is likewise low.  MDV strains , including the HVT strain (MDV seroty pe 3) , are not cons idered to be human pathogen s , and do not replicate in humans. The National Institutes of Health Guidelines for Research Involving Recombinant or Sy nthetic Nucleic Acid Molecules (NIH Guidelines) indicate that MDV is not associated with disease in healthy a dult humans and the lowest containment level (RG1) for human agents is recommended when used in laboratory work. 5 Insertion of the NDV gene has not increased virulence of the vaccine virus.  Q ualified personnel administering the vaccine could potentially be exposed to it through accidental injection, with the possibility of a local reaction . Although the safety of this specific vaccine has not been evaluated in humans and is thereforeunknown, accidental human injection is not expected to cause significant a dverse effects.  Millions of doses of various live HVT - vectored vaccines h ave previ ously been administered to chickens. No significant adverse events have been reported for those vaccines. **C. Environmental Safety**  The risks to the environment are low.  HVT replicates only

in avian - origin cells and is cell - associated. 6 A study perform ed b y the firm indicated that the NDV - HVT vaccine virus did not spread to HVT infected or naïve turkey poults, or to HVT infected or naïve chicks when administered subcutaneousl y to day- old SPF chicks.  In a comparison study conducted by

the firm, the parent and vaccine strains were inoculated into birds and on day s 7 and 28 post - inoculation, various organs were isolated and evaluated for the presence of virus. Results of the study indicated the tissue tropism was the same for both parental HVT and vaccine strain NDV - HVT.  A study

was performed by

the firm to compare the survivability of the parental HVT and the NDV - HVT on sterile shavings at room temperature (~25 o C). Neither virus was recovered after the initial day of inoculation.  The HV T backbone virus, the NDV gene and its site of insertion, the promoter, and the polyadenylation signal sequence have been used in previously licensed products. There have been no significant advers e effects to the environment as a result of their usage.  No bacterial DNA sequences , including no antibiotic resistance genes, have been inserted in the vaccine virus during its construction.  Confirmatory

testing was conducted at CVB to determine purity, s terility , identity , expression of immunogenic NDV protein, and stabil ity of the vaccine virus, with satisfactory

results.  The NDV gene did not react in the National Veterinary Services Laboratories surveillance testing for detection and differentiation of velogenic NDV and will not falsely

test positive as exotic NDV.  Recombination or horizontal gene transfer between HVT (serotyp e 3) and other MDV strains (serotyp es 1 and 2) has not been observed, perhaps due to the lower homology

among the seroty

pes. The f

irm conducted a study

to det ermine if co inoculation of the NDV - HVT vaccine with virulent MDV or with serot ypes 1 and 2 would perhaps result in recombination and a change in virulence. N o increase in virulence was observed and no indication of recombinati on was detected . The information above provides support to the claims made regarding the safety of the NDV - HVT vaccine to animals, publi c health, and the environment. There are no apparent substantial issues with adverse environmental impacts concerning use of this vaccine .**V. Alternatives** 

Two alternatives were considered. T he onl y alternative considered other than the preferred action alternative is not to approve the proposed field tests , the “no action” alternative. We have considered the applicants’ goals in light of the agency ’s public interest and responsibilities and any p otential environmental impact. Based upon the results of our risk analy sis and the potential applications for this vaccine in disease control, APHI S adopts the alternative th at the proposed field tests be approved. **VI. Conclusion**  Based upon the risk analysis documented in this EA, APHI S has determined that implementation of the proposal would not significantly affect the quality

of the human environment and that the preparation of an Environmental Impact Statement is not required (Finding of No Significant Impact). **References** 1. Dunn , J . 201 0 . Marek’s Disease in Poultry . In: The Merck Vet erinary Manual, Tenth Edition. C . M . Kahn , (Ed), Merck & Co., Inc., Whitehouse Station, N.J. Available online , last full review/revision July 2013 : http://www.merckmanuals.com/vet/poultry /neoplasms/mareks_disease_in_poultry . html# v3342416 2. Miller , P .J. 201 0 . Newcastle Disease in Poultry . In: The Merck Veterinary Manu al, Tenth Edition. C . M . Kahn , (Ed), Merck & Co., Inc., Whitehouse Station, N.J. Available online , last full review/revision January 2014 : http://www.merckmanuals.com/vet/poultry /newcastle_disease_and_other_param yx ovirus _infections/newcastle_disease_in_poultry .html 3 . Co de of Federal Regulations, Washington, DC. Available online: http://www.gpoaccess.gov/cfr/index.html 4. USDA Veterinary

Biological Products , Licensees and Permittees. 2014 , p 41 . Available online: http://www.aphis.usda.gov/animal_health/vet_biologics/publications/CurrentProdCodeB ook.pdf 5. The National Institutes of Health Guidelines for Res earch Involving Recombinant or Sy nthetic Nucleic Acid Molecules. March 2013, p 45. Available online: http://osp.od.nih.gov/sites/default/files/NIH_Guidelines_0.pdf 6. Purchase , H.G. , Burmester, B.R., and Cunningham, C.H. 1971 . Responses of cell cultures from various avian species to Marek’s disease virus and turkey Herpesvirus. Am J Vet Res 32:1811 - 1823.