title: [Significance of PRRS virus infections for respiratory tract infections in swine--a literature review].
abstract: The paper summarises present knowledge concerning the possible role of a virus which has in the meantime been classified as belonging to the arteriviridae and which causes PRRS (Porcine Reproductive and Respiratory Syndrome), in the pathogenesis of respiratory diseases four years after first isolation of the virus. Although the fact that PRRSV-infection produces an immunity which protects swine from repeated bouts of PRRSV is common knowledge by now, reinfection with the virus might be possible. An immunosuppression, which has been suggested by many investigators, and which was thought to be the result of destruction of alveolar macrophages during virus replication, was not found as yet. The significance of the extent and the duration of the decrease in the number of alveolar macrophages, which belong to the unspecific immunity, for the total immune system of swine infected with PRRSV remains unclear. A general impairment of specific immunity through PRRSV-infection could not be shown. The present role of PRRS for the pathogenesis of respiratory disease is seen very differently. The significance of PRRSV as primary cause of an "influenza-like" illness which is principally followed by severe bacterial infection of the respiratory tract, is questioned by the results of studies which identify PRRSV-infection as a mainly subclinical disease. In these studies, clinical cases are the exemption. Attempts at experimental reproduction of a clinically manifest, respiratory disease was not successful as yet. The paper describes factors which might be responsible for these variable results. Control of PRRS is difficult in areas with a high density of the swine population, since the spreading of the virus with the wind seems to be important besides the recruitment of new, infected animals. A vaccine has not yet been registered in Germany. First experimental experiences with vaccination are available from Denmark and the USA.
authors.affiliation: Epidemiologie der Tierärztlichen Hochschule Hannover, Bakum.
authors.forename: E
authors.initials: E
authors.lastname: Grosse Beilage
mesh_terms: D000818:Animals; D018018:Arterivirus / Q000502:physiology*; D018174:Arterivirus Infections / Q000175:diagnosis / Q000503:physiopathology / Q000662:veterinary*; D012008:Recurrence; D012141:Respiratory Tract Infections / Q000503:physiopathology / Q000662:veterinary* / Q000821:virology; D013552:Swine; D013553:Swine Diseases; D014779:Virus Replication