Archives of Virology

, Volume 143, Issue 3, pp 601–612 | Cite as

Comparative sequence analysis of open reading frames 2 to 7 of the modified live vaccine virus and other North American isolates of the porcine reproductive and respiratory syndrome virus

  • S. X. Yang
  • J. Kwang
  • W. Laegreid
Brief Report

Summary

To elucidate changes associated with the attenuated virulence in a modified live porcine reproductive and respiratory syndrome (PRRS) vaccine (Boehringer Ingelheim Animal Health, St. Joseph, MO), derived from an American prototype ATCC virus VR-2332, nucleotide sequence of 3′ genome covering open reading frames (ORFs) 2 to 7 coding regions from the vaccine virus was determined by RT-PCR with two overlapping fragments. Comparisons showed 98 base changes (94 substitutions, 3 deletions, and 1 addition) out of 3318 nucleotides between the vaccine virus and its parental virus. There were 15, 26, 17, 29, 9, and 6 base substitutions in ORFs 2, 3, 4, 5, 6, and 7, respectively, resulting in 5, 13, 8, 13, 2, and 3 amino acid (a.a.) substitutions in their deduced proteins, respectively. Most of these a.a. substitutions were also present in 17 known virulent/wild type PRRS virus isolates from North America. However, there were 1, 4, 1, and 1 unique a.a. substitutions in the vaccine virus ORFs 2, 3, 4, and 5 deduced proteins, respectively. These unique amino substitutions may be responsible for the attenuated virulence in the vaccine virus.

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Copyright information

© Springer-Verlag 1998

Authors and Affiliations

  • S. X. Yang
    • 1
  • J. Kwang
    • 1
  • W. Laegreid
    • 1
  1. 1.USDA, ARS, U.S. Meat Animal Research Center, Clay Center, Nebraska, U.S.A.USA

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