title: Immunisation of pigs with a major envelope protein sub-unit vaccine against porcine reproductive and respiratory syndrome virus (PRRSV) results in enhanced clinical disease following experimental challenge.
abstract: Disease exacerbation was observed in pigs challenged with virulent porcine reproductive and respiratory syndrome virus (PRRSV) following immunisation with a recombinant GP5 sub-unit PRRSV vaccine (rGP5) produced in E. coli. Eighteen animals were divided into three experimental groups: group A were immunised twice IM with rGP5, 21 days apart; group B acted as positive controls (challenged but not immunised); and group C were negative controls. Pigs in groups A and B were challenged 21 days after the second immunisation of the group A animals. Following challenge, three pigs given rGP5 exhibited more severe clinical signs than the positive controls, including respiratory distress and progressive weight-loss. Although not statistically significant, the more severe disease exhibited by group A animals may suggest previous immunisation as a contributory factor. The mechanisms of these findings remain unclear and no association could be established between the severity of disease, non-neutralising antibody concentrations and tissue viral loads.
authors: Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain.
authors: Cinta
authors: C
authors: Prieto
authors: Francisco Javier
authors: FJ
authors: Martínez-Lobo
authors: Francisco
authors: F
authors: Díez-Fuertes
authors: Patricia
authors: P
authors: Aguilar-Calvo
authors: Isabel
authors: I
authors: Simarro
authors: José María
authors: JM
authors: Castro
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D001483:Base Sequence; D004926:Escherichia coli / Q000276:immunology; D015686:Gene Products, env / Q000235:genetics* / Q000276:immunology*; D008969:Molecular Sequence Data; D019318:Porcine Reproductive and Respiratory Syndrome / Q000276:immunology / Q000503:physiopathology / Q000517:prevention & control*; D019316:Porcine respiratory and reproductive syndrome virus / Q000276:immunology* / Q000472:pathogenicity; D020539:Sequence Analysis, Protein; D034421:Sus scrofa; D013552:Swine; D013553:Swine Diseases / Q000503:physiopathology / Q000517:prevention & control* / Q000821:virology; D014611:Vaccination / Q000662:veterinary
chemical_list: D057134:Antibodies, Neutralizing; D015686:Gene Products, env