Susceptibility of mice to invasive aspergillosis correlates with delayed cell influx into the lungs.

Ubiquitous fungus Aspergillus fumigatus (A. fumigatus) is involved in invasive pulmonary aspergillosis (IPA), a frequent infection in immunocompromized patients. Genetic differences are likely to play a role predisposing to IPA. This study was aimed to compare six genetically different mouse strains in their susceptibility to IPA and to determine possible mechanisms involved in the pathogenesis of this infection. Immunosuppressed BALB/c and C57BL/6 mice infected with A. fumigatus conidia were more resistant to IPA than DBA/1, DBA/2, CBA, and A/Sn strains. Phagocytosis of A. fumigatus conidia by blood polymorphonuclear neutrophils (PMN) or bone marrow derived dendritic cells showed no difference between strains. All IPA susceptible strains demonstrated decreased PMN influx into the lungs during infection compared with resistant strains. Flow cytometry analysis of the composition of lung infiltrating cells showed that IPA susceptible mice had a decreased number of phagocytes before the infection. After infection the numbers of Gr-1(+)CD11b(+) PMN cells in the lungs of immunosuppressed mice increased from 10-20% to 50-60% while the percentage of CD11(+)F4/80(+) resident macrophages was unchanged. Among susceptible strains DBA/2 and A/Sn have a defect in C5 component of complement. Injection of normal serum into complement deficient but not into complement sufficient CBA or DBA/1 mice significantly improved their survival. We showed that complement replacement significantly increased PMN homing to the lungs of complement deficient mice. Thus, defect in complement system can predispose to IPA. Our results demonstrated that early influx of PMN into the lungs of mice is important for the resistance to IPA.

[Modeling antigenic determinants of the hepatitis A virus using synthetic peptides]. / Modelirovanie antigennykh determinant virusa gepatita A s pomoshch'iu sinteticheskikh peptidov.

Monoclonal and polyclonal anti-hepatitis A (HAV) antibodies were used to search for peptides mimicking the antigenic determinants of HAV. Synthetic peptides VP1 115-139, VP1 117-139, VP1 126-139, VP2 69-99, VP2 80-99, VP3 45-57, VP3 137-150, were shown to bind the anti-HAV antibodies in ELISA. Peptides VP1 115-139, VP1 117-139, VP2 69-99 were utilized to produce the antipeptide antibodies. Mice were immunized with the free peptides or with their conjugates with ovalbumin. Only the free VP2 69-99 caused formation of HAV binding antibodies.

[Synthesis of an artificial gene coding for thymosin alpha1 and its expression in Escherichia coli as a hybrid with human tumor necrosis factor]. / Sintez iskusstvennogo gena, kodiruiushchego timozin alpha1, i ego ékspressiia v Escherichia coli v sostave gibridov s faktorom nekroza opukholei cheloveka.

Chemical-enzymatic synthesis and cloning in Escherichia coli of an artificial gene encoding the immunoactive peptide thymosin alpha 1 have been carried out. Recombinant plasmids were constructed which contain fusion genes coding for hybrids of human tumour necrosis factor (TNF) and thymosin alpha 1 as N- or C-terminal part of the hybrid protein. In the C-terminal hybrid protein, TNF and thymosin alpha 1 are linked through a methionine residue, thus allowing for thymosin alpha 1 to be cleaved off the rest of the hybrid protein with cyanogen bromide. In case of the N-terminal hybrid protein, the linker between the thymosin alpha 1 and TNF sequences is the acid-labile dipeptide Asp-Pro. Expression of the hybrid genes in E. coli and properties of the recombinant proteins were studied. The N-terminal hybrid protein was secreted into periplasmic space, in contrast with the C-terminal hybrid protein, which formed insoluble aggregates inside bacterial cells. Procedures for the isolation of both hybrid proteins were developed. The N-terminal hybrid protein displayed full biological activity in the cytotoxic assay on the mouse fibroblast L-929 whereas the C-terminal hybrid protein proved to be much less active. Treatment of the hybrid protein TNF-thymosin alpha 1 with cyanogen bromide lead to a mixture of two polypeptides, from which thymosin alpha 1 was purified to homogeneity by simple chromatographic procedures.

[The antigenic properties of hepatitis A virus particles possessing different physicochemical characteristics]. / Antigennye svoistva chastits virusa gepatita A, obladaiushchikh razlichnymi fiziko-khimicheskimi kharakteristikami.

A modified enzyme immunoassay based on adsorption of antihepatitis A virus (HAV) IgG-HRPO conjugate and monoclonal antibodies to HAV were used to investigate antigenic differences between mature HAV virions and subviral particles with different buoyant densities in CsCl produced in HAV-infected cells. The mature virions (1.34 g/cm3) appeared to have common antigenic determinants with subviral particles (1.20, 1.27, and 1.30 g/cm3) and possess some additional determinants. Nevertheless, both subviral particles and mature virions induced antibodies capable of neutralizing HAV infectivity in tissue culture.

[Hybrid human lymphokine genes. I. Design of recombinant plasmids coding hybrids of immune interferon and human tumor necrosis factor]. / Geny gibridnykh limfokinov cheloveka. I. Konstruirovanie rekombinantnykh plazmid, kodiruiushchikh gibridy immunnogo interferona i faktorov nekroza opukholei cheloveka.

Recombinant plasmids coding for hybrid proteins between human interferon gamma and human tumour necrosis factor alpha or beta have been constructed using site-directed mutagenesis. The genes were fused via a synthetic oligonucleotide linker coding for tetrapeptide Pro-Val-Gly-Pro. The fused genes were expressed in Escherichia coli under control of early promoters of bacteriophage T7. E. coli cells harbouring the plasmids with the hybrid genes gave rather high level of the fused proteins biosynthesis. The hybrid recombinant proteins proved to be unstable in E. coli cells.

[Expression in Escherichia coli of DNA coding for human tumor necrosis factor]. / Ekspressiia v Escherichia coli DNK, kodiruiushchei faktor nekroza opukholei cheloveka.

The variants of expression in Escherichia coli of artificial DNA coding for human tumor necrosis factor, an important immune modulator with selective cytotoxic action on a number of transformed cell lines have been described. The DNA was placed under control of either phage M13 promoter of gene for main coat protein or tandem of pair of E. coli tryptophane promoters. It has been shown that E. coli cells harbouring plasmids described with artificial TNF gene provide good level of protein biosynthesis. The protein has been purified by anion exchange chromatography near to homogeneity and used for preparation of monoclonals. As result three hybridomas effectively produced high affinity monoclonal anti-TNF antibodies have been obtained and characterized.

[Production in vivo of macrophage migration inhibition and stimulation factors in the inductive phase of the alloimmune response]. / Produktsiia in vivo faktorov podavleniia i stimuliatsii migratsii makrofagov v induktovnoi faze alloimmunnogo otveta.

Macrophage migration inhibition and stimulation factors were revealed in the serum of alloimmune mice by polyacrylamide gel electrophoresis. CBA mice were primed intravenously with 90 X 10(6) and challenged subsequently intravenously with 20 X 10(6) spleen cells of BALB/c mice. Macrophage migration inhibition and stimulation factors were revealed in pre- and post-albumin fractions, respectively, already on days 1 and 6 after alloimmunization. It is suggested that at an early phase of immune response the immunomediators with alternative functions whose local activity gradients predetermined the macrophage behaviour, are released into the serum of alloimmune animals.

[Nonidentity of Lyt phenotypes and the radiosensitivity of early and late producers of macrophage migration inhibitory factor in reaction to H-2 complex antigens]. / Neidentichnost' Lyt-fenotipov i radiochuvstvitel'nosti "rannikh" i "pozdnikh" produtsentov faktora podavleniia migratsii makrofagov pri reaktsii na antigeny kompleksa H-2.

MIF production induced at different times after intravenous immunization of mice with irradiated allogeneic splenic cells showed different sensitivity to the treatment with anti-Lyt-antibodies and to gamma-irradiation. The "early" MIF producers induced several hours after alloimmunization were sensitive to irradiation at a dose of 500 rad and to the treatment with anti-Lyt-1- and anti-Lyt-2-antibodies and complement, while the "late" MIF producers which appeared 21 days after alloimmunization were resistant to irradiation at doses of 500 and 1500 rad and to the treatment with anti-Lyt-2-antibodies but sensitive to anti-Lyt-1-antibodies. It is supposed that the "early" MIF producers of the Lyt-1+2+ phenotype are immature precursors of T cells which, in contradistinction to the "late" MIF producers of the Lyt-1+2+ phenotype, are activated and produce MIF without proliferation after a twofold contact with antigen.