Opsonized Virulent Brucella abortus Replicates within Nonacidic Endoplasmic Reticulum-Negative LAMP-1-Positive Phagosomes in Human Monocytes

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Bryan H. Bellaire (Creator)

James A. Cardelli (Creator)

R. Martin II Roop (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: Cells in the Brucella spp. are intracellular pathogens that survive and replicate within host monocytes. Brucella maintains persistent infections in animals despite the production of high levels of anti-Brucellaspecific antibodies. To determine the effect of antibody opsonization on the ability of Brucella to establish itself within monocytes the intracellular trafficking of virulent Brucella abortus 2308 and attenuated hfq and bacA mutants was followed in the human monocytic cell line THP-1. Early trafficking events of B. abortus 2308- containing phagosomes (BCP) were indistinguishable from those seen for control particles (heat-killed B. abortus 2308 live Escherichia coli HB101 or latex beads). All phagosomes transiently communicated the early-endosomal compartment and rapidly matured into LAMP-1 cathepsin D and acidic phagosomes. By 2 h postinfection however the number of cathepsin D BCP was significantly lower for live B. abortus 2308-infected cells than for either Brucella mutant strains or control particles. B. abortus 2308 persisted within these cathepsin D LAMP-1 and acidic vesicles; however at the onset of intracellular replication the numbers of acidic B. abortus 2308 BCP decreased while remaining cathepsin D and LAMP-1 . In contrast to B. abortus 2308 the isogenic hfq and bacA mutants remained in acidic LAMP-1 phagosomes and failed to initiate intracellular replication. Notably markers specific for the host endoplasmic reticulum were absent from the BCPs throughout the course of the infection. Thus opsonized B. abortus in human monocytes survives within phagosomes that remain in the endosomal pathway and replication of virulent B. abortus 2308 within these vesicles corresponds with an increase in intraphagosomal pH. Originally published Infection and Immunity Vol. 73 No. 6 June 2005

Additional Information

Publication

Other

Infection and Immunity. 73:6(June 2005) p. 3702-3713.

Language: English

Date: 2011

Keywords

monocytes, opsonization, Brucella abortus

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