+1 Recommend
0 collections
      • Record: found
      • Abstract: found
      • Article: not found

      Dual infections of feeder pigs with porcine reproductive and respiratory syndrome virus followed by porcine respiratory coronavirus or swine influenza virus: a clinical and virological study


      Read this article at

          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.


          Dual infections of pigs with porcine reproductive and respiratory syndrome virus (PRRSV) followed by a second common respiratory virus, either porcine respiratory coronavirus (PRCV) or swine influenza virus (SIV), were studied. The aim was to determine if dual infections, as compared to single virus infections, result in enhanced clinical manifestations. It was also examined if PRRSV replication affects replication of PRCV or SIV in the respiratory tract. Groups of conventional 10 week old pigs were inoculated with PRRSV-only (3 pigs), PRCV-only (4 pigs) or SIV-only (4 pigs). Dual inoculations with PRRSV-PRCV (4 pigs) and PRRSV-SIV (3 groups of 4, 4 and 5 pigs) were performed at a 3 day interval. A group of uninoculated control pigs (8 pigs) was included.

          The infection with PRRSV-only induced a transient fever (40.2°C) at 2 DPI, but no respiratory signs. The PRCV-only infection remained subclinical. The SIV-only infection resulted in a one day fever (40.1°C) with moderate tachypnoea and dyspnoea. Mean weight gain in the virus-inoculated groups was retarded compared with the control group.

          The PRRSV-PRCV infection induced a 9 day lasting fever (peak 40.9°C) with tachypnoea, dyspnoea and productive coughing. The PRRSV-SIV infection resulted in fever and respiratory signs in all 3 groups. Clinical signs, however, were more pronounced in group 1 than in groups 2 and 3. Pigs of group 1 showed fever during 10 days (peak 41.4°C), tachypnoea, marked dyspnoea with abdominal breathing, and a productive cough. Pigs of groups 2 and 3 had fever for 5 and 3 days (peaks 40.6 and 40.3°C) respectively and mild respiratory disorders. Mean weight gain during 14 DPI of the 2nd virus was 5.9 kg in the PRRSV-PRCV group and 4.0, 6.8 and 6.7 kg in PRRSV-SIV groups 1, 2 and 3 respectively. Mean weight gain during the corresponding period in the PRRSV-only group was 8.6 kg. It was concluded that dual infections with viruses causes more severe disease and growth retardation than single PRRSV infection.

          PRCV excretion curves were similar in single and dual virus inoculated groups. Excretion of SIV was delayed by 2 days in the dual inoculated pigs. Thus, replication of the second virus is not (PRCV) or only slightly (SIV) affected by a prior infection with PRRSV.

          Related collections

          Most cited references14

          • Record: found
          • Abstract: found
          • Article: not found

          Sites of replication of a porcine respiratory coronavirus related to transmissible gastroenteritis virus

          A porcine respiratory coronavirus (prcv) was inoculated by aerosol into nine hysterectomy-derived and colostrum-deprived pigs at the age of one week. They were killed at different times after inoculation and tissues were sampled for virus isolation and immunofluorescence. Results indicate that virus replicated to high titres in the respiratory tract. Replication mainly occurred in alveolar cells but also in epithelial cells of nasal mucosa, trachea, bronchi, bronchioli, in alveolar macrophages and in tonsils. After primary replication in the respiratory tract, viraemia occurred. Virus also reached the gastrointestinal tract after swallowing. Subsequently, PRCV was observed to replicate in the ileum. The infection spread within a few days from the ileum to the duodenum. Replication in the small intestine remained limited to a few cells located in or underneath the epithelial layer of villi and, or, crypts. The cell type could not be identified. Virus was isolated from mesenteric lymph nodes in all pigs, but immunofluorescence was not observed. Results show that small changes in molecular structure between transmissible gastroenteritis virus and prcv resulted in important changes in host cell tropism.
            • Record: found
            • Abstract: found
            • Article: not found

            Pathological, ultrastructural, and immunohistochemical changes caused by Lelystad virus in experimentally induced infections of mystery swine disease (synonym: porcine epidemic abortion and respiratory syndrome (PEARS)).

            The pathogenicity and pathogenesis of Lelystad virus was studied in six 6-day-old SPF piglets. A third passage of the agent was propagated on porcine alveolar macrophages and intranasally inoculated into pigs. Pigs were killed at hours 24, 48, 60, and 72, and on days 6 and 8 after inoculation. From day 2 on pigs developed diffuse interstitial pneumonia with focal areas of catarrhal pneumonia, and from this day on splenic red pulp macrophages were enlarged and vacuolated. Lelystad virus was re-isolated from the lungs of infected pigs from day 2 after inoculation. Lelystad virus antigens were detected by immunohistochemical techniques in bronchiolar epithelium and alveolar cells, and in spleen cells of infected pigs from day 2 after inoculation. Ultrastructural examination of tissues by electron microscopy revealed degenerating alveolar macrophages and epithelial cells in lungs and nasal mucosa, with excessive vacuolation of the endoplasmic reticulum. Although the respiratory tract seems to be the target organ for this virus, macrophages in other organs, such as the spleen, can also be infected. This preference for macrophages may impair immunological defences.
              • Record: found
              • Abstract: found
              • Article: not found

              Prevalence of infections with enzootic respiratory and enteric viruses in feeder pigs entering fattening herds.

              The prevalence of infections with H1N1- and H3N2-influenza viruses, porcine respiratory coronavirus (PRCV), transmissible gastroenteritis virus (TGEV) and porcine epidemic diarrhoea virus (PEDV) in feeder pigs shortly after their entry into fattening units was examined. Ten groups of pigs with acute respiratory disease during the months September to October 1991 and seven groups of pigs with acute diarrhoea during the months February to March 1992 were investigated. On arrival in the fattening herds, more of the pigs were negative for antibodies against H1N1-influenza virus and against PRCV during September to October (61 and 50 per cent, respectively) than in February to March (51 and 34 per cent, respectively). There was serological evidence of a triple infection with PRCV and both influenza viruses in seven of the 17 groups; dual infections with PRCV and H1N1-influenza virus occurred in nine groups and with H1N1- and H3N2-influenza viruses in one group. Seroconversion against TGEV was not detected in any of the 17 groups, but seven of them had seroconverted to PEDV. Multiple infections with PRCV and either one or both of the influenza viruses were thus very common shortly after the introduction of feeder pigs into the fattening herds. There was no association between the type and/or multiplicity of these infections and respiratory disease, but infections with PEDV were clearly associated with outbreaks of diarrhoea.

                Author and article information

                Vet Microbiol
                Vet. Microbiol
                Veterinary Microbiology
                Published by Elsevier B.V.
                26 April 1999
                February 1996
                26 April 1999
                : 48
                : 3
                : 325-335
                Laboratory of Veterinary Virology, Faculty of Veterinary Medicine, University of Gent, Salisburylaan 133, B-9820 Merelbeke, Belgium
                Author notes

                University of Gent, Faculty of Veterinary Medicine, Salisburylaan 133, 9820 Merelbeke, Belgium. Tel: 32 9 264 7366, Fax: 32 9 264 7495.

                Copyright © 1996 Published by Elsevier B.V.

                Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.

                : 13 July 1994
                : 9 June 1995

                Veterinary medicine
                porcine reproductive and respiratory syndrome virus,porcine respiratory coronavirus,swine influenza virus,dual infections,pigs


                Comment on this article