Experimental coinduction of type D retrovirus-associated pulmonary carcinoma and lentivirus-associated lymphoid interstitial pneumonia in lambs.

Two retrovirus-associated pulmonary diseases of sheep [ovine pulmonary carcinoma (OPC); sheep pulmonary adenomatosis], a bronchoalveolar carcinoma, and lymphoid interstitial pneumonia (LIP) were induced simultaneously in 9 of 9 neonatal lambs. The lambs were killed 8-28 weeks after intratracheal injection of lung tumor homogenate or lung fluid derived from sheep with naturally occurring OPC and ovine lentivirus (OvLV) infection. The inoculated lambs developed multifocal neoplasms of alveolar type II cells or nonciliated bronchiolar epithelial cells, LIP, and pulmonary lymph node hyperplasia, and all produced antibody to OvLV. OvLV was isolated from 6 to 7 lambs tested, and infectious center assay of pulmonary lavage cells from 3 lambs revealed that approximately 1 in 1,000 pulmonary lavage cells contained infectious lentivirus. Neither contact control lambs nor control lambs that received ultrafiltered lung fluid developed evidence of either disease or of OvLV infection. Lung fluid or tumor tissue of lambs with OPC contained a 26,000-dalton protein that cross-reacted with antiserum to p27 to Mason-Pfizer monkey virus, a type D retrovirus. The fact that no antigenic cross-reaction between OvLV and type D retroviruses has been demonstrated supports the presence of two retroviruses in sheep with OPC. Although the contributions of each agent to oncogenesis in this model are difficult to evaluate, the rapid development of two retrovirus-induced pulmonary diseases in experimentally inoculated lambs suggests an etiologic or pathogenetic synergism between these two members of the family Retroviridae.

Effect of selected cytokines on the replication of Corynebacterium pseudotuberculosis and ovine lentiviruses in pulmonary macrophages.

Opportunistic bacterial pathogens that induce monokine secretion by pulmonary alveolar macrophages (PAM) are frequently encountered complicating factors in lentivirus-associated pneumonias in ungulates and man. We examined the effect of selected cytokines on the replication of Corynebacterium pseudotuberculosis and ovine lentivirus (OvLV) in ovine PAM. Recombinant bovine (rBo) IL 1 beta, rBoIL-2, rBo interferon-gamma (IFN gamma) and rBoTNF alpha, alone and in combination at physiological doses had no apparent effect on the extracellular growth of C. pseudotuberculosis, compared with the growth of the pathogen in medium alone. Untreated ovine PAM, derived from bronchoalveolar lavage, were found to substantially reduce, but not eliminate the growth of C. pseudotuberculosis in culture. This bactericidal effect was neither enhanced nor inhibited by pretreatment of PAM with the recombinant bovine cytokines or low doses of LPS that induce monokines. In contrast, addition of rBoTNF alpha or rBoIL-1 beta, at physiological doses, at the initiation of, or on Day 4, after OvLV infection resulted in a significant increase in viral replication in PAM, as measured in an antigen capture assay for OvLV p25, compared with untreated infected cells. This effect was more pronounced with lower levels of infecting OvLV, and, in the case of TNF alpha, was abrogated by preincubation of the cytokine with specific anti-serum. Conversely, in most instances, inclusion of rBoIFN alpha in OvLV-infected PAM cultures resulted in a significant decrease in viral replication. These results suggest that these soluble mediators that are probably secreted in response to C. pseudotuberculosis infection may have little direct effect on the extra- or intracellular survival of the bacteria in the lung, but may modulate lentiviral replication and, by extension, disease expression, in sheep with dual infection.

Replication and cytopathic effects of ovine lentivirus strains in alveolar macrophages correlate with in vivo pathogenicity.

Ruminant lentiviruses share genomic sequences and biologic properties with human immunodeficiency viruses. Four ovine lentivirus strains were assessed for cytopathic effects and virus replication. Lentivirus isolate H/24 produced high virus titers and lysis of synovial cells but replicated slowly and caused no fusion of alveolar macrophages. Lentivirus isolates 84/28 and 85/14 produced low virus titers, less syncytia, and limited or no cell lysis in synovial cells and macrophages. In contrast, ovine lentivirus isolate 85/34 produced early peak virus titers and caused rapid fusion and lysis of both macrophages and synovial cells. Ovine lentivirus isolates which were cytopathic for macrophages induced lymphoproliferative disease when inoculated into lambs.

Class II antigen processing defects in two H2d mouse cell lines are caused by point mutations in the H2-DMa gene.

The molecular nature of the defect in two mouse antigen processing-defective cell lines was examined. Both mutants were derived from the A20 (BALB/c, H2d) B cell line, and both were found to have defects in the H2-DMa gene. Mutant 3A5 exhibits severely reduced amounts of H2-DMa message, and no detectable DMalpha protein. cDNA sequence revealed a C-->T transition at nucleotide 118, introducing a premature stop codon in exon 2 of the H2-DMa gene. In contrast, mutant 2A2 exhibits reduced but detectable levels of H2-DMa message and DMalpha protein only after treatment with IL-4, which induces the expression of both the H2-DMa and the H2-DMb genes in B cells. In this mutant the cDNA sequence revealed a missense mutation in exon 3 resulting in the conversion of a conserved proline residue in the Ig-like domain to serine. Stable transfection with full-length H2-DMa cDNA reconstitutes the antigen processing capacity of both mutants, as demonstrated by the ability to present native antigen to T cell clones, and by restored class II SDS stability.

Retrovirus-associated ovine pulmonary carcinoma (sheep pulmonary adenomatosis) and lymphoid interstitial pneumonia. I. Lesion development and age susceptibility.

To determine the lesion development of retrovirus-induced ovine pulmonary carcinoma (OPC), ten neonatal lambs were inoculated intratracheally with either 1) lung fluid preparations derived from a sheep with Type D retrovirus-associated OPC and concurrent ovine lentivirus (OvLV)-associated lymphoid interstitial pneumonia (LIP) (n = 8); or 2) lung fluid from a sheep with only OvLV-LIP (n = 2). Seven of eight neonates that received Type D retrovirus-associated OPC/OvLV-LIP lung fluid developed both OPC and LIP lesions between 9 and 32 weeks after inoculation. Mild OPC lesions consisted of foci of type II alveolar epithelial cells lining alveoli surrounded by minimal alveolar macrophage infiltrates. More severe OPC lesions consisted of multifocal aggregates of cuboidal to columnar neoplastic cells forming acini or masses associated with abundant alveolar macrophage infiltrates. Lesions of LIP consisted of peribronchiolar and perivascular lymphoid hyperplasia and heterogeneous interstitial leukocytic infiltrates. The two neonates that received OvLV-LIP lung fluid developed rapid and severe LIP, but not OPC lesions. Two lambs (inoculated as neonates with virus-free lung fluid) and three lambs (uninoculated contacts) served as controls and did not develop OPC. To investigate age susceptibility for development of OPC, 20 additional lambs within defined age groups (neonates, 2 weeks old, 5 weeks old, and 10 weeks old) received ultracentrifuged tumor homogenate. Neonatal to 5-week-old lambs inoculated with Type D retrovirus-associated OPC/OvLV-LIP tumor homogenate were equally likely to develop OPC, but lambs inoculated at 10 weeks of age were more refractory to tumor development.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigen processing of two H2-IEd-restricted epitopes is differentially influenced by the structural changes in a viral glycoprotein.

The factors that influence the intracellular location(s) of MHC class II-restricted epitope loading remain poorly understood. We present evidence that two I-Ed-restricted epitopes of the influenza hemagglutinin (HA) molecule, termed site 1 (S1; encompassing amino acid residues 107-119) and site 3 (S3; encompassing amino acid residues 302-313), are generated in distinct endocytic compartments. By means of an epitope-specific mAb, we show that S1 becomes detectable in late endocytic/lysosomal vesicles; using a mutant cell line, we also show that the presentation of S1 is dependent upon H2-DM expression. In contrast, S3; presentation is H2-DM-independent and appears in early endosomes as a result of acid-induced structural changes in HA. Presentation of both epitopes can be made H2-DM-independent by denaturing HA and made H2-DM-dependent by preventing the acid-induced conformational changes from occurring. These findings indicate that the structural context of a given epitope can determine where it is processed.