Date of Award

1983

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Biological Sciences

Keywords

Biology, General.

Rights

CC BY-NC-ND 4.0

Abstract

Neutral protease activity was quantified during the course of influenza virus infection in both embryonated chicken eggs and cell culture systems. Characterization and monitoring changes of trypsin-like activities in egg embryonal fluids and subcellular fractions of HBSC-1 and primary chick embryo cells (CE) were carried out by a sensitive fluorometric technique. Antigenic subtypes of influenza A viruses studied were H1N1 strains PR/8/34, Brazil/8/78, FM/1/47, the H3N2 strain Bangkok/1/80, the H5N9 Turkey/Ontario/7732/66 and the Sendai strain of parainfluenza type 1 virus. Viruses allantoically inoculated into embryonated eggs markedly altered protease activity of fluid in the cavity. The three distinct types of allantoic fluid protease profiles detected had features in common. In all profiles, periodic peaks of protease activity always preceded the partial shut down of protamine cleaving proteases which paralleled the production of near maximal titers of infectious virus. Translocation of PR and Turkey virus occurred with amniotically infected eggs, as evidenced by high infectious virus titers and decreased protease activities in allantoic fluids. To elucidate the mechanism involved in this reduction of proteolytic activity, infectious allantoic fluids were analyzed for the presence of protease inhibitors and enzymes with carboxypeptidase B activity. Acid-heat treated 48 hour virus-infected allantoic fluids of different influenza strains could effectively inhibit the activities of subtilisin and allantoic fluid proteolytic enzymes. Using the dipeptide glycyl-L-lysine in the fluorometric assay, the level of proteases with carboxypeptidase B-like specificity in PR virus infected allantoic fluid remained approximately at control levels throughout the 48 hour test period. Based on these findings, it seems that influenza virus induced inhibitors dictate the partial shut down of allantoic fluid protamine cleaving proteases thereby enabling carboxypeptidase B activity to predominate. Protease profiles in the membrane + granule and cytosol fractions of PR and Brazil infected HBSC-1 and primary CE cells were unique for each virus tested. However, in all profiles, the appearance of infectious virus was accompanied by gradually decreasing protease levels while a reduction or absence of infectious virus enhanced activity in both subcellular fractions. Thus, a correlation appears to exist between the level of proteolytic activity and degree of influenza virus infectivity.Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1983 .E927. Source: Dissertation Abstracts International, Volume: 44-10, Section: B, page: 2966. Thesis (Ph.D.)--University of Windsor (Canada), 1983.

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