title: Analysis of open reading frame 5 in Japanese porcine reproductive and respiratory syndrome virus isolates by restriction fragment length polymorphism.
abstract: For the epidemiological survey of porcine reproductive and respiratory syndrome virus (PRRSV) isolated in Japan, the open reading frame (ORF) 5 gene of 37 field isolates in Chiba prefecture from 1991 to 1999 were analyzed by restriction fragment length polymorphism (RFLP). Reverse tanscription-polymerase chain reaction (RT-PCR) amplifying the ORF 5 gene detected 35 field isolates except for 2 isolates. RFLP analysis with MluI, HincII, SacII, HaeIII and MspI demonstrated that 35 field isolates were divided into 14 distinct codes and 34 isolates were distinguished from VR2332-derived modified live PRRSV vaccine, indicating the existence of genetic diversity in PRRSV field isolates in Japan. Only one strain 98-4A had an RFLP pattern identical to the vaccine strain. Nine out of the 35 field isolates (25.7%) had the RFLP code 1-3-2-1-1 and these patterns occurred throughout the examination period. This suggests that these isolates are the prevailing strain of PRRS in Chiba prefecture. RFLP with 5 enzymes demonstrated that various strains existed in the same year, and that there were different codes on the same farm according to the year. These observations indicate that there is a genetic variation among field isolates in very limited regions and some viruses possess the ability to cause their own genomic substitutions within a herd in a short time.
authors.affiliation: Department of Preventive Veterinary Medicine and Animal Health, Nihon University School of Veterinary Medicine, Fujisawa, Kanagawa, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Itou
authors.forename: M
authors.initials: M
authors.lastname: Tazoe
authors.forename: T
authors.initials: T
authors.lastname: Nakane
authors.forename: Y
authors.initials: Y
authors.lastname: Miura
authors.forename: T
authors.initials: T
authors.lastname: Sakai
mesh_terms: D000818:Animals; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D007564:Japan / Q000453:epidemiology; D016366:Open Reading Frames; D012150:Polymorphism, Restriction Fragment Length; D019318:Porcine Reproductive and Respiratory Syndrome / Q000453:epidemiology / Q000821:virology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D013552:Swine
chemical_list: D004279:DNA, Viral; D012367:RNA, Viral