title: Comparison of pathological changes and viral antigen distribution in tissues of calves with and without preexisting bovine viral diarrhea virus infection following challenge with bovine herpesvirus-1.
abstract: OBJECTIVE
  To compare pathological changes and viral antigen distribution in tissues of calves with and without preexisting subclinical bovine viral diarrhea virus (BVDV) infection following challenge with bovine herpesvirus-1 (BHV-1).
  
  
  METHODS
  24 Friesian calves.
  
  
  METHODS
  12 calves were inoculated intranasally with noncytopathic BVDV-1a; 12 days later, 10 of these calves were challenged intranasally with BHV-1 subtype 1. Two calves were euthanized before and 1, 2, 4, 7, or 14 days after BHV-1 inoculation. Another 10 calves were inoculated intranasally with BHV-1 only and euthanized 1, 2, 4, 7, or 14 days later. Two calves were inoculated intranasally with virus-free tissue culture fluid and euthanized as negative controls. Pathological changes and viral antigen distribution in various tissue samples from calves with and without BVDV infection (all of which had been experimentally inoculated with BHV-1) were compared.
  
  
  RESULTS
  Following BHV-1 challenge, calves with preexisting subclinical BVDV infection had earlier development of more severe inflammatory processes and, consequently, more severe tissue lesions (limited to lymphoid tissues and respiratory and digestive tracts) and greater dissemination of BHV-1, compared with calves without preexisting BVDV infection. Moreover, coinfected calves had an intense lymphoid depletion in the Peyer patches of the ileum as well as the persistence of BVDV in target organs and the reappearance of digestive tract changes during disease progression.
  
  
  CONCLUSIONS
  In calves, preexisting infection with BVDV facilitated the establishment of BHV-1 infection, just as the presence of BHV-1 favors BVDV persistence, thereby synergistically potentiating effects of both viruses and increasing the severity of the resultant clinical signs.
authors.affiliation: Department of Comparative Pathology, Veterinary Faculty, University of Córdoba-Agrifood Campus of International Excellence (ceiA3), Edificio Sanidad Animal, Campus de Rabanales, 14014, Córdoba, Spain.
authors.forename: María A
authors.initials: MA
authors.lastname: Risalde
authors.forename: Verónica
authors.initials: V
authors.lastname: Molina
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: Sónchez-Cordón
authors.forename: Miriam
authors.initials: M
authors.lastname: Pedrera
authors.forename: Fernando
authors.initials: F
authors.lastname: Romero-Palomo
authors.forename: María J
authors.initials: MJ
authors.lastname: Bautista
authors.forename: Alberto
authors.initials: A
authors.lastname: Moreno
authors.forename: José C
authors.initials: JC
authors.lastname: Gómez-Villamandos
mesh_terms: D000818:Animals; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000473:pathology* / Q000821:virology; D002417:Cattle; D004279:DNA, Viral / Q000302:isolation & purification; D001908:Diarrhea Viruses, Bovine Viral; D006566:Herpesviridae Infections / Q000662:veterinary* / Q000821:virology; D007242:Herpesvirus 1, Bovine; D008168:Lung / Q000648:ultrastructure / Q000821:virology; D008297:Male; D012367:RNA, Viral / Q000302:isolation & purification
chemical_list: D004279:DNA, Viral; D012367:RNA, Viral