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.
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.
Prieto
Cinta
C
Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain.
Martínez-Lobo
Francisco Javier
FJ
Díez-Fuertes
Francisco
F
Aguilar-Calvo
Patricia
P
Simarro
Isabel
I
Castro
José María
JM
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
D057134:Antibodies, Neutralizing; D015686:Gene Products, env