Scand. J, Immunol. 36, Suppl. 11. 75-80. 1992
Evidence of Immunosuppression by Bovine Respiratory Syncytial Virus Z. WOLDEHIWET & R. SHARMA University of Liverpool, Department of Veterinary Pathology. Veterinary Field Station. Leahurst. Neston. Wirral, UK
Woldehiwet Z, Sharma R. Evidence of immunosupprcssion by Bovine Respiratory Syncytia! Virus. Scand J Immunol 1992:36(Suppl. 11 ):75 80 Rcspiraiory syncyiia! virus (RSV) is a major respiratory palhtigen in human infants and calves. Calves and lambs intecied with bovine RSV show mild clinical signs but they arc more susceplible lo secondary infection with Paxleuretla haemolyiico. Lambs nif'eciod with P hucuuilyiiia 6 days after experimental infection with bovine RSV had signiftcanily greater magnitudes of fever, higher disease and lesion scores and higher mortality rates than those infected with P. htwmolviica or bovine RSV alone (/'d samples were collected from all groups of lambs before infeetion and at ditTerrm limes posl-moculation or. when alveolar macrophages were assayed for antigen presentation, just before killing. Mononuclear cells (MNC) were separated from diluted blood on a Ficoll Paquc column. When the MNC were used to assiiy the capacity of normal or bovine RSV-infetted macrophages to present antigens, the adherent cell fraction was remined by tnLubatittg blood monotiuclear cells in plastic Petri dishes at 17 C in a CO; incubator for 4 h. Mommmtcitr (tiiiihitilks. Monoclonal antibodich were kindly provided by Dr M. R. Brandon, University of Melbourne, Australia. The monoclonal antibodies u.sed in the present study were 25-91,44-3S, .VX-65. 20-96 and 2S-1 which recognize the CDS, CD4. C DS. LCA p22t) and Class 11 antigens respectively. The percentages of MNC bearing epitopes for the different lymphocyte subsets, in peripheral bloinJ or lung lavage fluid, were established by flow cytometry as described earlier 112). Mont^Klonal antibodies and rabbit complement were used to prepare CD4-enriehed and COK-enriched as described earlier 11.1] The?*- depleted pt^ipulations were used m L7 asays. using binine RSV antigen or phytohaemagglutinin (PHA). Bonne RSi' iinUgcn. Bovine RSV antigen used in iransfonnation assiiys was prepared from lamb icslis cell cultures and concentrated and purified as previously descnbeii[l4] Lymphosyn- iransformtiiion assay.s. Lymphocyli; transformation il.T) assays were performed as previously described |I5|. E.xp.\urt' of AM to twfinc HSy. The AM were exposeil lo bovine RSV as destribed earlier [16]. Nornml AM or AM previously exposed to hnvine RSV were then used as antigen prt-senting cells in an LT assay system using PHA i>r bovine RSV antigen and homologous peripheral blood lymphocytes, depleted of adherent cells, obtained before iheeolleciion ofthe lung lavage fluid. Normul and bovine RSV-infected .-XM were used to compare their capacity to prc-senl RSV antigen and the mitogen PMA to normal lymphtwytes by (he lymphocyte transformation test.
of data. The paired (Student's) /-t«t was used to compare values obtained before and after experimental inrceiion wuh Uivine RSV and to compare values obtained from lambs infected with bovine RSV and /' hot-molytUit or one agent alone. RESULTS Infection wiih bovine RSV was characterized by mild respiratory signs atid pathological changes. However, latnbs experimentally infected with bovine RSV and /*. haemolyiku had significantly more severe clinical disease and higher disease and lesion scores. Five of the K animals infected with bovine RSV ;nid P. haemolytica died with severe respiratory disease 2 to 5 days after exposure to P. luwmolytira compared with no deaths m the group of 8 Iambs infected with bovine RSV alone and one death in the group of 8 lambs infected wiih P. haemolytica alone. A comparison of the gross pathological lesions among the three gn>ups showed that lambs infected with bovine RSV and P. havmolyticu had larger and more severe lung lesions than those infected with cither agent atone (Table I). Effects offmvine /tSy on bovine lymphocytes MNC obtained from lambs infected with bovine RSV were significantly more susceptible to P. haciui'lytuii cytotoxin than mononuclear cells obtained from control lambs (/*
Evidence of Immunosuppression by Bovine Respiratory Syncytial Virus Z. WOLDEHIWET & R. SHARMA University of Liverpool, Department of Veterinary Pathology. Veterinary Field Station. Leahurst. Neston. Wirral, UK
Woldehiwet Z, Sharma R. Evidence of immunosupprcssion by Bovine Respiratory Syncytia! Virus. Scand J Immunol 1992:36(Suppl. 11 ):75 80 Rcspiraiory syncyiia! virus (RSV) is a major respiratory palhtigen in human infants and calves. Calves and lambs intecied with bovine RSV show mild clinical signs but they arc more susceplible lo secondary infection with Paxleuretla haemolyiico. Lambs nif'eciod with P hucuuilyiiia 6 days after experimental infection with bovine RSV had signiftcanily greater magnitudes of fever, higher disease and lesion scores and higher mortality rates than those infected with P. htwmolviica or bovine RSV alone (/'d samples were collected from all groups of lambs before infeetion and at ditTerrm limes posl-moculation or. when alveolar macrophages were assayed for antigen presentation, just before killing. Mononuclear cells (MNC) were separated from diluted blood on a Ficoll Paquc column. When the MNC were used to assiiy the capacity of normal or bovine RSV-infetted macrophages to present antigens, the adherent cell fraction was remined by tnLubatittg blood monotiuclear cells in plastic Petri dishes at 17 C in a CO; incubator for 4 h. Mommmtcitr (tiiiihitilks. Monoclonal antibodich were kindly provided by Dr M. R. Brandon, University of Melbourne, Australia. The monoclonal antibodies u.sed in the present study were 25-91,44-3S, .VX-65. 20-96 and 2S-1 which recognize the CDS, CD4. C DS. LCA p22t) and Class 11 antigens respectively. The percentages of MNC bearing epitopes for the different lymphocyte subsets, in peripheral bloinJ or lung lavage fluid, were established by flow cytometry as described earlier 112). Mont^Klonal antibodies and rabbit complement were used to prepare CD4-enriehed and COK-enriched as described earlier 11.1] The?*- depleted pt^ipulations were used m L7 asays. using binine RSV antigen or phytohaemagglutinin (PHA). Bonne RSi' iinUgcn. Bovine RSV antigen used in iransfonnation assiiys was prepared from lamb icslis cell cultures and concentrated and purified as previously descnbeii[l4] Lymphosyn- iransformtiiion assay.s. Lymphocyli; transformation il.T) assays were performed as previously described |I5|. E.xp.\urt' of AM to twfinc HSy. The AM were exposeil lo bovine RSV as destribed earlier [16]. Nornml AM or AM previously exposed to hnvine RSV were then used as antigen prt-senting cells in an LT assay system using PHA i>r bovine RSV antigen and homologous peripheral blood lymphocytes, depleted of adherent cells, obtained before iheeolleciion ofthe lung lavage fluid. Normul and bovine RSV-infected .-XM were used to compare their capacity to prc-senl RSV antigen and the mitogen PMA to normal lymphtwytes by (he lymphocyte transformation test.
of data. The paired (Student's) /-t«t was used to compare values obtained before and after experimental inrceiion wuh Uivine RSV and to compare values obtained from lambs infected with bovine RSV and /' hot-molytUit or one agent alone. RESULTS Infection wiih bovine RSV was characterized by mild respiratory signs atid pathological changes. However, latnbs experimentally infected with bovine RSV and /*. haemolyiku had significantly more severe clinical disease and higher disease and lesion scores. Five of the K animals infected with bovine RSV ;nid P. haemolytica died with severe respiratory disease 2 to 5 days after exposure to P. luwmolytira compared with no deaths m the group of 8 Iambs infected with bovine RSV alone and one death in the group of 8 lambs infected wiih P. haemolytica alone. A comparison of the gross pathological lesions among the three gn>ups showed that lambs infected with bovine RSV and P. havmolyticu had larger and more severe lung lesions than those infected with cither agent atone (Table I). Effects offmvine /tSy on bovine lymphocytes MNC obtained from lambs infected with bovine RSV were significantly more susceptible to P. haciui'lytuii cytotoxin than mononuclear cells obtained from control lambs (/*
