Tryptase Clara, a trypsin-like protease localized exclusively in and secreted from Clara cells to the bronchial epithelium of rat, proteolytically activates the infectivity of influenza A virus [H. Kido, Y. Yokogoshi, K. Sakai, M. Tashiro, Y. Kishino, A. Fukutomi, and N. Katunuma (1992) J. Biol. Chem. 267, 13573-13579]. We report here that human mucus protease inhibitor (MPI), a major inhibitor of granulocyte elastase in the lining fluids of the human respiratory tract, significantly inhibited proteolytic activation of the infectivity of influenza A and Sendai viruses by tryptase Clara in vitro and multi-cycles of mouse-adapted influenza A virus replication in rat lungs in vitro. Recombinant MPI and the C- but not the N-terminal domain of the MPI inhibited both the proteolytic activity of tryptase Clara and the activation of virus infection. The 50% inhibitory concentrations of recombinant MPI and the C-terminal domain for tryptase Clara with Sendai virus envelope glycoprotein as substrate were 7.4 and 61.6 nM, respectively. These results indicate that MPI is a defensive compound against virus infection. Since there is evidence suggesting that concentrations of MPI in respiratory fluids are insufficient for prevention of virus infection, administration of MPI in the airway may be useful for treatment of these virus infections.

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Monoclonal antibodies for identification of Borrelia japonica isolated from tick, Ixodes ovatus and long-tailed shrew, Sorex unguiculatus in Japan and Borrelia related to Lyme disease (Borrelia burgdorferi sensu lato) were prepared and characterized. All isolates belonging to B. japonica and isolates from I. dentatus and cottontail rabbit in North America reacted with MAb 01441b against flagellin which was prepared from immunized mice with strain HO14, type strain of B. japonica, but isolates from I. persulcatus, patient, and wood mouse, Apodemus speciosus ainu, in Japan, and isolates belonging to B. burgdorferi, B. garinii and B. afzelii from North America and Europe did not. Strains used in this study reacted with MAb P62 against common antigen which was prepared from immunized mice with strain NT24 isolated from I. persulcatus in Japan, but B. japonica did not. These MAbs are useful for identification and differentiation of B. japonica and B. burgdorferi sensu lato in Japan.

Infectivity of Borrelia burgdorfieri strain 297 in normal outbred ddY mice was examined. Strain 297 was inoculated intraperitoneally in 3-week-old outbred ddY mice. B. burgdorferi was routinely cultured from the heart and urinary bladder 5 to 84 days postinoculation. The combined isolation rate from both heart and