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Herpes felis infections belong to the feline viral rhinotracheitis complex. Acyclovir, a virustatic of the nucleoside-analogue-group, inhibits the in vitro replication of herpesvirus felis. Acyclovir (0.1% in isotonic saline solution) is well tolerated by cats when applied t.i.d. subcutaneously and has a high and long lasting plasma level. The treatment is not too expensive.
The T4 (CD4) molecule has been shown to facilitate the interactions of T cells with HLA class II determinants, to function as a signal transducing molecule, and to serve as a receptor for HIV. Recent studies demonstrated that both phorbol esters and antigen stimulation induced the rapid and transient modulation and phosphorylation of T4 on an IL-2-dependent line of cloned peripheral blood T4+ cells. In the current study, we define the kinetics of T4 phosphorylation and internalization induced by phorbol esters and determine the extent to which this metabolic pathway is required for T cell proliferation, activation, and HIV infection. On both peripheral blood T4+ cells and the T cell line Sup-T1, the modulation and internalization of surface T4 induced by phorbol 12, 13-dibutyrate (PDB) was preceded by rapid and transient phosphorylation. On both cell types, by 48 h, T4 was reexpressed on the cell surface in a nonphosphorylated form and was shown to be resistant to phosphorylation and internalization when these cells were reexposed to PDB. In contrast, T4 on the surface of PBL was neither phosphorylated nor down-modulated when PBL were stimulated by PHA, indicating that these effects were not simply the result of T cell activation or proliferation. In additional studies, we demonstrate that this pathway for T4 phosphorylation and internalization is not required for HIV infection by showing that 1) the binding of the HIV gp 120 envelope to T4 does not induce phosphorylation of T4, 2) Sup-T1 cells that are rendered resistant to phorbol ester-induced T4 internalization and phosphorylation by prolonged culture in PDB remain highly susceptible to HIV infection, and 3) clones of HIV-producing cells expressing high levels of surface T4 that is complexed with viral envelope remain susceptible to PDB-induced modulation of T4. This observation suggests that, at least on lymphoid cells, HIV penetration does not occur exclusively by R-mediated endocytosis.
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Comparative study of the sensitivities of immunofluorescent microscopy (IFM), enzyme immunoassay, (EIA), and lectin test (LT) in the detection of influenza virus antigen in nasopharyngeal washings from patients with influenza, acute respiratory diseases, pneumonia, and laryngitis has been carried out. EIA modification (used in this study) based on the detection of a complex of viral core proteins (M + RNP) has been shown to be no less sensitive than IFM and suitable for use in the rapid diagnosis of influenza. It can be used in combination with other methods. The optimum time for collecting the washings off is day 2 from the disease onset for analysis by EIA technique and day 4 for LT.
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Pet cats, persistently infected with feline leukemia virus and having lymphosarcoma, were treated by extracorporeal immunoadsorption using Staphylococcus aureus Cowan I (which has protein A on its surface) to remove immunoglobulin G and circulating immune complexes. Complete viral clearance and long-lasting tumor regression were achieved following such treatments in 9 of 16 cats. In addition, in vitro immunologic assays have been developed that are useful in the clinical evaluation of cats during treatment.
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A retrospective analysis was performed of 105 patients with polymyositis for eight years. Roentgenographic evidence of pulmonary interstitial disease was present in ten adult patients (9%) with polymyositis unassociated with other connective-tissue disorders. Review of the pulmonary histopathologic findings indicated a spectrum of pulmonary diffuse interstitial infiltrates and fibroplasia of the alveolar septae. Response to glucocorticoids with regard to pulmonary symptoms was variable in the patients studied. Therapeutic response seemed to be influenced by both the cellularity of the chronic interstitial infiltrates and the degree of fibroplasia of the alveolar septae. Electron microscopic studies of the lung tissue from two patients with polymyositis and diffuse interstitial lung disease failed to demonstrate either immune complexes or viral particles.
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Autoimmune mechanisms presumably involved in the pathogenesis of HIV infection and AIDS are presented. The possible role of similarity between antigens of the major histocompatibility complex and viral antigens in the development of immune system impairment are discussed.
What will oral health care be like in the 21st century? During the 20th century, American dental education evolved from freestanding and often proprietary schools to become an integral part of research-intensive university professional education. This evolution provided a formidable scientific basis for diagnosis, therapeutics, disease prevention, and health promotion. The development of clinical skills coupled with advanced dental materials and therapeutics has truly been remarkable. And now we approach the 21st century as a nation of changing demographics. By 2010, nearly 40 million Americans will be 65 years old or older. Expectations for "quality of life" now punctuate American values. In 1900, the human life span was 45 years, but today it approaches 80 years. Although in 1900, the primary causes of mortality and morbidity were acute infectious diseases, today our challenges include complex viral-infectious as well as neoplastic and chronic disabling diseases (e.g., chronic facial pain, musculoskeletal degeneration, osteoporosis, osteoarthritis, and cerebrovascular and coronary diseases and disorders). In fact, one American dies every hour from oral cancer. Changes in the practice of clinical dentistry in the 21st century will: (1) integrate dental practice into comprehensive health care; (2) become increasingly proactive for health promotion; (3) represent an increased knowledge-base and computer-assisted technology approach for diagnostics and therapeutics; and (4) use novel strategies for oral health care ranging from gene-mediated therapeutics to community-based health promotion.
Viral, bacterial, protozoal, and cancer-associated Ags elicit strong responses in human gammadelta T lymphocytes. The majority of these cells in the peripheral blood express the Vgamma9Vdelta2-encoded TCR and recognize nonpeptidic phosphoantigens without an apparent MHC restriction. We have shown that Vgamma9Vdelta2 T cells express the inhibitory CD94/NKG2 receptor for HLA class I molecules. The anti-CD94 mAb inhibits 1) the Vgamma9Vdelta2 T cell proliferation in response mycobacterial phosphoantigens and 2) the HIV-induced Vgamma9Vdelta2 T cell expansion. Vgamma9Vdelta2 T cells stimulated with nonpeptidic mycobacterial antigens produce IFN-gamma and TNF-alpha. Signaling through the CD94/NKG2 receptor interferes with the synthesis of these cytokines. The CD94/HLA class I interaction is also involved in the cytotoxic activity of Vgamma9Vdelta2 T cells. The Vgamma9Vdelta2 T cell regulation through the CD94 receptor may be important for the potentially dual function in innate immunity, i.e., 1) NK-like and 2) TCR ligand-induced cytolytic activities.
A complex mechanism may be operational for dendritic cell (DC) maturation, wherein Toll-like receptor and other signaling pathways may be coordinated differently depending on the nature of the pathogens, in order for DC maturation to be most effective to a given threat. Here, we show that IFN-alpha/beta signaling is selectively required for the maturation of DCs induced by double-stranded RNA or viral infection in vitro. Interestingly, the maturation is still observed in the absence of either of the two target genes of IFN-alpha/beta, TLR3 and PKR (double-stranded-RNA-dependent protein kinase R), indicating the complexity of the IFN-alpha/beta-induced transcriptional program in DCs. We also show that the DCs stimulated in vivo by these agents can migrate into the T cell zone of the spleen but fail to mature without the IFN signal. The immune system may have acquired the selective utilization of this cytokine system, which is essential for innate antiviral immunity, to effectively couple with the induction of adaptive immunity.
The formation of a multimeric nucleoprotein complex by the phage phi 29 dsDNA binding protein p6 at the phi 29 DNA replication origins, leads to activation of viral DNA replication. In the present study, we have analysed protein p6-DNA complexes formed in vitro along the 19.3 kb phi 29 genome by electron microscopy and micrococcal nuclease digestion, and estimated binding parameters. Under conditions that greatly favour protein-DNA interaction, the saturated phi 29 DNA-protein p6 complex appears as a rigid, rod-like, homogeneous structure. Complex formation was analysed also by a psoralen crosslinking procedure that did not disrupt complexes. The whole phi 29 genome appears, under saturating conditions, as an irregularly spaced array of complexes approximately 200-300 bp long; however, the size of these complexes varies from approximately 2 kb to 130 bp. The minimal size of the complexes, confirmed by micrococcal nuclease digestion, probably reflects a structural requirement for stability. The values obtained for the affinity constant (K(eff) approximately 10(5) M-1) and the cooperativity parameter (omega approximately 100) indicate that the complex is highly dynamic. These results, together with the high abundance of protein p6 in infected cells, lead us to propose that protein p6-DNA complexes could have, at least at some stages, during infection, a structural role in the organization of the phi 29 genome into a nucleoid-type, compact nucleoprotein complex.
A complex of the polyomavirus internal protein VP2/VP3 with the pentameric major capsid protein VP1 has been prepared by co-expression in Escherichia coli. A C-terminal segment of VP2/VP3 is required for tight association, and a crystal structure of this segment, complexed with a VP1 pentamer, has been determined at 2.2 A resolution. The structure shows specific contacts between a single copy of the internal protein and a pentamer of VP1. These interactions were not detected in the previously described structure of the virion, but the location of VP2 in the recombinant complex is consistent with features in the virion electron-density map. The C-terminus of VP2/VP3 inserts in an unusual, hairpin-like manner into the axial cavity of the VP1 pentamer, where it is anchored strongly by hydrophobic interactions. The remainder of the internal protein appears to have significant flexibility. This structure restricts possible models for exposure of the internal proteins during viral entry.
Studies were performed to identify a pair of primers, specific for the tick-borne encephalitis (TBE) virus complex of the Flaviviridae, with which to develop a rapid and specific identification system based on reverse transcription and the polymerase chain reaction (RT-PCR). The specificity of a putative primer pair was examined by RT-PCR of representative viruses from other antigenic complexes of the Flaviviridae and by computer sequence homology checks. All viruses of the TBE complex tested, with a single exception, were identified by RT-PCR using the identified primer pair. Accumulated data suggest that one of the putative primers identified in these studies may have flavivirus group specificity. The advantages of such a primer in the development of identification systems for all virus complexes of the Flaviviridae is discussed.
The integrase (IN) protein of the human immunodeficiency virus (HIV) mediates two distinct reactions: (i) specific removal of two nucleotides from the 3' ends of the viral DNA and (ii) integration of the viral DNA into target DNA. Although IN discriminates between specific (viral) DNA and nonspecific DNA in physical in vitro assays, a sequence-specific DNA-binding domain could not be identified in the protein. A nonspecific DNA-binding domain, however, was found at the C terminus of the protein. We examined the DNA-binding characteristics of HIV-1 IN, and found that a stable complex of IN and viral DNA is formed in the presence of Mn2+. The IN-viral DNA complex is resistant to challenge by an excess of competitor DNA. Stable binding of IN to the viral DNA requires that the protein contains an intact N-terminal domain and active site (in the central region of the protein), in addition to the C-terminal DNA-binding domain.
The role of simian virus 40 (SV40) large tumor antigen (T antigen) as a DNA helicase at the replication fork was studied. We found that a T-antigen hexamer complex acts during the unidirectional unwinding of appropriate DNA substrates and is localized directly in the center of the fork, contacting the adjacent double strand as well as the emerging single strands. When bidirectional DNA unwinding, initiated at the viral origin of DNA replication, was analyzed, a larger T-antigen complex that is simultaneously active at both branch points of an unwinding bubble was observed. The size and shape of this helicase complex imply that the T-antigen dodecamer complex, assembled at the origin and active in the localized melting of duplex DNA, is subsequently also used to continue DNA unwinding bidirectionally. Then, however, the dodecamer complex does not split into two hexamer subunits that track along the DNA; rather, the DNA is threaded through the intact complex, with the concomitant extrusion of single-stranded loops.