Efficacy of a transmissible gastroenteritis coronavirus with an altered ORF-3 gene.
Serial passage of virulent transmissible gastroenteritis virus through cell culture reduced its virulence in 3-day-old piglets. Intramuscular inoculation of pregnant gilts with 2 doses of this modified-live virus elicited a level of lactogenic immunity that protected their nursing piglets against a lethal dose of challenge virus. Sequence analysis of a 637-bp fragment of the spike gene containing most of the aminopeptidase receptor and the 4 major antigenic sites from the original and the serially passed viruses were nearly identical. Gel analysis revealed that the fragment from the ORF-3 gene of virulent virus was smaller than the corresponding fragment from the serially passed virus. Sequence analysis of the fragment from the passed virus revealed that the sequence between nt 5310 and nt 5434 was replaced by a 636-bp fragment from the polymerase 1A gene. This replacement resulted in the loss of the CTAAACTT leader RNA-binding site and ATG start codon for the ORF-3A gene but it did not affect the ORF-3B gene.
Woods
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RD
National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, Iowa 50010, USA. rwoods@nadc.ars.usda.gov
D000818:Animals; D000831:Animals, Newborn; D000833:Animals, Suckling; D000914:Antibodies, Viral / Q000096:biosynthesis / Q000097:blood; D001483:Base Sequence; D017931:DNA Primers; D005260:Female; D005761:Gastroenteritis, Transmissible, of Swine / Q000276:immunology / Q000517:prevention & control*; D007112:Immunity, Maternally-Acquired / Q000276:immunology*; D008892:Milk / Q000276:immunology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011247:Pregnancy; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012692:Serial Passage / Q000662:veterinary; D013552:Swine; D005760:Transmissible gastroenteritis virus / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity; D014765:Viral Vaccines / Q000235:genetics / Q000276:immunology / Q000592:standards*; D014774:Virulence / Q000235:genetics / Q000276:immunology
D000914:Antibodies, Viral; D017931:DNA Primers; D014765:Viral Vaccines