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 Porcine Reproductive and Respiratory Syndrome
Vaccine
, Respiratory Form, Modified Live Virus

Novem ber 201 3

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 Porcine Reproductive and Respiratory Syndrome VaccineEnvironmental Assessment f or Field Testing of a Porcine Reproductive and Respiratory Syndrome Vaccine, Respiratory Form,
Modified Live Virus

I

. Proposed Action

APHIS is considering granting authorization to ship an unlicensed Porcine Reproductive and Respiratory Syndrome (PRRS) Vaccine

, Respiratory Form, Modified Live Virus , for
field safety testing in pig s

. ProtaTek International, Inc., St. Paul, Minnesota, has requested authorization to conduct the field safety tests under conditions of husbandry that are typical of the commercial swine industry in the United States. The vaccine is intended for use in healthy pigs, three weeks of age or older, as an aid in the reduction of lung lesions caused by PRRS virus (PRRSV).

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 efficacious and not worthless, contaminated, dangerous, or h armful. Accordingly, APHIS has conducted
a risk analysis and has concluded that, regarding intramuscular administration of this single

- dose vaccine in swine, the safety risks to animals, public health, and the environment are low. A copy of the firm’s risk analysis with confidential business
information re dact ed is available online and by request, as indicated in the Federal Register Notice announcing the pro posed field testing

. APHIS considers the firm’s risk analysis, but also review s other studies and tests conducted by the firm, the confirmatory testing completed by APHIS personnel on the Master Seed to confirm the vaccine’s purity, sterility, identity, a nd expression of immunogenic protein, and results of literary and regulatory review regarding this and similar previously tested or licensed products.

Based on APHIS ’ analysis of the relevant data, a preliminary determination has been
reached that field testing this veterinary vaccine will not have a significant impact on the

q uality 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 cl ose 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

PRRSV is a positive

- stranded RNA virus in the Arteroviridae family, with a genome of
about 15 kb. 1 The virus causes reproductive failure in sows and re spiratory disease in young pigs postweaning

. 2 Treatment options are limited ; PRRS continues to be a major challenge for swine veterinarians and produce rs . The best strategy is prevention using good management, biosecurity, and vaccination. 2, 3 PRRSV is not associated with disease in healthy adult humans.The vaccine is a chimeric virus constructed from an infectious PRRSV clone backbone

encoding nons tructural proteins and a portion of a field isolate encoding the structural proteins

. The chimeric clone contain s a genetic marker , i.e. a DNA polylinker that can be

use d to differentiate vaccine virus from field isolates of PRRSV.

The proposed field s afety test will be conducted in at least three different geographical
locations . T he product will be used according to instructions on the product circular

, and in accordance with standard requirements published in Title 9, Code of Federal Regulations (CFR), Part 103.3, concerning shipment of experimental biological products
for use in animals. 4

The potential for escape and dispersal of the experimental vaccine from the proposed release sites is low. The personnel to conduct the study are experience d in porc ine health
management.

III. Need for the Proposed Action

PRRSV causes widespread disease in both the US and European pig industries, with
more than $6 64 million lost annually by US swine producers. 5 The firm proposes to produce an efficacious , safe vaccine using a chimeric virus, as an aid in the prevention of respiratory disease due to PRRSV

.

It is expected that the data from these monitored field trials will confirm the safety of this

PRRS V accine , Respiratory Form, Modified Live Virus, f or use in swine at least 3 weeks of age within the environment of the United States.

IV. Areas of Concerns

The three areas of concern to APHIS are: 1) animal safety, 2) public health, and 3) environmental safety. APHIS has conducted its own risk analysis to assess whether risks are associated with the proposal to field test this experimental vaccine. The safety characteristics of this vaccine have been thoroughly evaluated. The conclusions derived from the risk analysis for each of the areas of concern are summarized below.

A. Animal Safety

The risk to animals is low.

 Fifteen three

- week

- old vaccinated pigs and eleven controls from the same litters were challenged thirty

- five days post

- vaccination. Fourteen days later, necropsies
indicated si gnificant protection in the vaccinated pigs compared to the non

vaccinated controls, average 2.8% lesions vs. average 27.7% lesions

, respectively.

 The vaccine is attenuated, but the virus can replicate in swine

. Vaccination will induce a viremia in pigs which is transitory. The firm reports that sentinel pigs adjacent to vaccinates remained negative for the PRRS vaccine virus when testedby qPCR, virus isolation

, or PRRSV

- specific antibody test during the course of one study.

 Backpassage studies conduc ted by the firm involved passage five times in three

week

- old pigs . T he fifth passage virus was then injected into pregnant sows at 90 days gestation as well as another group of 3 week

- old pigs. No reversion to virulence occurred: the pigs did not develo p respiratory disease and the sows gave birth to healthy piglets.

 The genetic stability of the master seed virus was demonstrated in Marc145 cell culture at passages 1 and 15 (the highest used in vaccine production), w hich shared 100% identity for an impor tant structural gene. Genotypic stability in vivo was shown by inoculation of three pigs with virus that was passaged five times in
three

- week

- old pigs previously. After isolation of three virus samples from each of the three pigs, gene sequencing of a m ajor structural gene indicated that they were 100% identical to the pass five virus, which was 99.6% identical to the
master seed virus. The genetic polylinker marker was maintained in the viral

genome

.

 Various species including mice, rats, and guinea pig s are resistant to PRRSV. However, some species of birds, especially mallard ducks, are sus ceptible to wild
type PRRSV. 6 The attenuated vaccine virus was not recovered by viral isolation or detected by qPCR when injected into mallard ducks during a 28

- d ay study conducted by the firm. No le sions were found in tissue samples collected from heart, lungs, liver, spleen, kidney, stomach, small intestine, large intestine, lymph nodes, thymus and muscle.

B. Public Health

The risk to public health is likewi se low.

 PRRSV is not considered to be a human pathogen, and does not replicate in
humans.

 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 therefore unknown, accidental human injection is not expected to cause significant adverse effects.

 Many doses of various live PRRSV vaccines h ave previously been administered

to swine . No significant adverse events have been reported for those vaccines.

C. Environmental Safety

The risks to the environment are low.

 Several c onventional, attenuated live PRRSV vaccine s have been previously developed, licensed, and made available for commercial use , without undue
environmental effects

. 7

 The stability and identity of the master seed was tested by the firm at passage s 1
and 15 in Marc 145 cell culture , using RT

- PCR and sequencing of a major structural gene to demonstrate 100% equivalence. APHIS testing at the Centerfor Veterinary Biologics (CVB) showed a high degree of stability and identity between passages 1 and 15 in four significant genomic regions of interest that

were sequenc ed. A PHIS

- CVB testing a lso demonstrated excellent protein expression by the master seed at passage s 1 and 15, using both fluorescent

a ntibody in tissue culture and Western blot analysis

.

 The master seed and another chimeric virus were co

- cultured in Marc145 cells by
the firm for 4

- 5 days and viral RNA extracted. RT

- PCR and analysis of PCR products indicated that recombination and horizontal gene transfer did not occur.

 Shed/spread studies in pigs were conducted by the firm

. Using virus isolation,

q PCR, and E LISA testing on blood samples, four pigs housed adjacent to the vaccinated pigs and three of four commingled pigs were negative by all three tests. One commingled pig was positive on day 28 only by qPCR and virus isolation, but negative by ELISA . All nasal, fecal, and urine samples collected were negative by virus iso lation. All samples from the sixteen vaccinated pigs were negative on day 28.

 The vaccine virus w as evaluated by the firm for survival at room temperature. After 24 hours, no vi rus wa s detected under dry conditions

. U nder liquid
conditions

, virus titer was reduced by ~2.4 logs and not detected at all after 4 days

. Risks associated with surviving virus are further reduced given the narrow host range, attenuation, and reduced tra nsmi ssion to commingled or adjacent pigs

, noted previously

.

The information above provides support to the claims made regarding the safety of the

PRRS vaccine to animals, public 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 only alternative considered other than t he 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 potential environmental impact. Based upon the
results of our risk an alysis and the potential applications for this vaccine in disease control, APHIS adopts the alternative that the proposed field tests be approved.

VI. Conclusion

Based upon the risk analysis documented in this EA, APHIS 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. Dea, S., Gagnon, C.A., Maardassi, B., et al . 2000. Current knowledge on the structural proteins of porcine reproductive and respiratory syndrome (PRRS) virus: comparison of the North American and European isolates. Arch Virol 145:659

- 688.
2. Overview of Porcine Reproductive and Respiratory Syndro me . In: The Merck Veterinary Manual, Tenth Edition, 2010. S.E. Aiello & M.A. Moses (Eds), Merck & Co., Inc., Whitehouse Station, N.J. Available online: http://www.merckmanuals.com/vet/index.html

3. Ov erview of Health

- Management Interaction : Pigs . In: The Merck Veterinary Manual, Tenth Edition, 2010. S.E. Aiello & M.A. Moses (Eds), Merck & Co., Inc., Whitehouse Station, N.J. Available online:
ht tp://www.merckmanuals.com/vet/index.html

4. Code of Federal Regulations, Washington, DC. Available online: http://www.gpoaccess.gov/cfr/index.html
5. Swine vets, researchers encouraged to submit PRRS proposals. 2013. Pork Network.
Available online: http://www.porknetwork.com/pork

- news/Swine

- vets

- researchers

- encouraged

- to

submi t

- PRRS

- proposals

- 219274431.html

6. Zimmerman, J.J., Yoon, K.

- J., Pirtle, E.C., et al . 1997. Studies of porcine reproductive and respiratory syndrome virus infection in avian species. Vet Micro
55:329

- 336.

7. USDA Veterinary Biological Products, Licensees and Pe rmittees. 2013, p45.
Available online: http://www.aphis.usda.gov/animal_health/vet_biologics/publications/CurrentProdCod eBook.pdf