To determine whether hepatitis B virus (HBV) regulates the expression of the human fl-interferon gene, a series of recombinant bovine papilloma virus plasmids containing the human interferon gene and various fragments of the HBV genome were constructed and used to transform C127 cells, a murine fibroblast line. Analysis of the DNA from transformed C127 cells indicated that the interferon gene was intact and that the plasmids replicated as stable multicopy elements. The 1828-base-pair BamHI HBV DNA fragment containing the core antigen gene, but not the 2755-base-pairBgl II HBV DNA fragment encoding both the surface antigen and the X antigen, suppressed the production of human fl-interferon. No effect by any of the recombinant plasmids on the synthesis of murine interferon was detected. The suppression of human f-interferon by HBV occurs via a trans-acting factor.A frameshift mutation within the HBV core gene alleviates the inhibitory activity; thus we infer that the core protein is this factor or is crucially associated with this activity. was cloned into the same BamHI site of the plasmid pdBPV-1, which had one of the two BamHI sites destroyed (19). The resulting plasmids, pBHC and pBHS (Fig. 1), were used in further plasmid constructions. The plasmid pIFR containing the human Pinterferon gene as a 1.6-kilobase (kb) EcoRI-HindIII fragment (20) was linearized by digestion with EcoRI and the EcoRI ends were converted to HindIII ends. Following digestion with HindIII, the resulting 1.6-kb HindIII fragment containing the human 8-interferon gene was isolated and inserted into the HindIII site of (i) pdBPV-1, (it) pBHS, and (iii) pBHC, resulting in the formation of pBI, pBHSI, and pBHCI, respectively (Fig. 1).An insertion mutation at the Taq I site (mp 2014) that is within the HBV core antigen gene was created by digesting circularized 1828-bp BamHI HBV DNA fragments with Taq I. The linearized fragment was filled-in, ligated, and then cleaved with BamHI. The resulting BamHI HBV DNA fragment then was cloned into the BamHI site of pBI, yielding pBIHCdTaqI. The insertion mutation resulted in the destruction ofthe Taq I site in the HBV core antigen gene and in a shift in the open reading frame.Cell Cultures and DNA Transfections. Murine C127 fibroblasts were grown as described (20). One day before transfection, 8 x 104 cells were plated in each well of a 24-well plate; the cells were refed with fresh medium 4 hr before transfection. C127 cells were transfected by the calcium phosphate precipitation technique (21) with 0.2 Ag of total plasmid DNA that included 50 ng of a plasmid containing the neomycin-resistance gene. Eight hours after transfection, cells were diluted and G418 (600 ,ug/ml) was added. After 14-21 days, well-separated foci were picked and stable transformants were grown to confluence in the presence of G418.Interferon Induction and Assay. Induction of interferon by poly(I)-poly(C) in C127 cells that had been confluent for 4 days was performed as described (20). Uninduced cells were treated in t...

Alveolar macrophages from Pneumocystis carinii-infected rats are defective in phagocytosis. To investigate whether this defect is due to a certain factor present in P. carinii-infected lungs, alveolar macrophages from uninfected rats were incubated with bronchoalveolar lavage (BAL) fluid samples from P. carinii-infected rats. Alveolar macrophages treated with these BAL fluid samples became defective in phagocytosis but remained normal when treated with BAL fluid samples from noninfected or Toxoplasma gondii-infected rats. The suppressive activity of the BAL fluid samples from P. carinii-infected rats on phagocytosis was retained when the BAL fluid samples were passed through a filter with a pore size of 0.45 m but was lost when the BAL fluid samples were digested with proteases such as trypsin, pepsin, papain, or endopeptidase Gly-C. Lipid fractions of these BAL fluid samples had no suppressive activity on phagocytosis. The suppressive activity of these BAL fluid samples was also lost when they were incubated with concanavalin A-agarose beads, suggesting that the inhibitor is a glycoprotein. The inhibitor was estimated to be larger than 100,000 Da by exclusion filtration. After binding to the concanavalin A-agarose beads, the inhibitor in BAL fluid samples and P. carinii lysate could be eluted with 200 mM methylmannose. Treatment of both the crude BAL fluid samples and P. carinii lysate and the 200 mM methylmannose eluate with antibody against the major surface glycoprotein of P. carinii eliminated their suppressive activity. These results suggest that the factor capable of suppressing the phagocytic activity of alveolar macrophages is P. carinii major surface glycoprotein or one or more of its derivatives.An important function of alveolar macrophages is to clear foreign particles and infectious agents from the lung. Their role in the defense against Pneumocystis carinii infection is demonstrated by the observation that transtracheally inoculated P. carinii organisms are not cleared in alveolar macrophage-depleted rats (31). Administration of granulocyte-macrophage colony-stimulating factor, which activates alveolar macrophages (40), decreases the severity of P. carinii pneumonia (34). This finding also indicates the importance of alveolar macrophages in the clearance of Pneumocystis organisms.The alveoli are constantly exposed to foreign material and microorganisms. The alveolar macrophage maintains a low level of activation to engulf and destroy these materials while inhibiting an overly reactive inflammatory reaction to foreign objects encountered. To accomplish this, alveolar macrophages inhibit antigen presentation by dendritic cells (20), limit the expansion of lymphocyte populations (38), and restrict pulmonary lymphocyte functions (19). When activated, alveolar macrophages become proinflammatory and produce interleukin-8, which attracts neutrophils and lymphocytes by chemotaxis, as well as interleukin-1␤, tumor necrosis factor alpha, interleukin-6, and granulocyte-macrophage colony-stimulating factor, wh...

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Synthetic peptides and murine monoclonal antibodies were used to map cross-reactive chlamydial epitopes. A species-specific epitope in the central region of variable sequence region 4 abuts the amino-terminal end of a B-serogroup-specific or F/G-serogroup-specific epitope, which in turn abuts known serovar-specific epitopes. The carboxyl-terminal portion of variable sequence region 4 (residues 297 to 314) comprises a region of end-to-end B-cell epitopes in some serovars of the B and F/G serogroups.