Synthesis of gliotoxin-neutralising antibodies and assessment of their activity in murine invasive aspergillosis

Ref ID: 19216

Author:

R. Ben-Ami*, I. Benhar, V. Dergachev, Y. Shadkchan, N. Osherov

Author address:

Aviv, IL

Full conference title:

23rd European Congress of Clinical Microbiology and
Infectious Diseases

Date: 27 April 2014

Abstract:

Objectives: Invasive aspergillosis (IA) is associated with poor outcomes in immunosuppressed hosts. Suppression of angiogenesis by the Aspergillus metabolite gliotoxin (GT) may facilitate tissue hypoxia and persistent infection. We hypothesized that GT-neutralizing antibodies (GTnAb) would restore angiogenic activity and promote fungal clearance and host survival.
Methods: We immunized BALB/c mice alternately with GT conjugated to bovine albumin and keyhole limpet hemocyanin. Successful conjugation was determined by Western blot and GT antiserum titer was determined by ELISA. The ability of antisera to neutralize GT activity was tested using a Matrigel angiogenesis assay. Lastly, we assessed treatment with GTnAb, alone and in combination with amphotericin B, in a murine model of IA using 2 immunosuppression regimens: cortisone alone (non-neutropenic model) and cyclophosphamide/cortisone (neutropenic model). Control mice were treated with pre-immune sera. Mortality and tissue fungal burden (qPCR) were compared among treatment arms.
Results: BALB/c mouse immunization resulted in high titers (>1:50,000) of GT-specific antibodies. Antisera reversed the in vitro antiangiogenic activities of GT and Aspergillus culture filtrates, indicating high titers of GTnAb. GTnAb significantly reduced the pulmonary fungal burden in non-neutropenic (P=0.0001), but not in neutropenic mice. Conversely, GTnAb significantly increased the survival rate of neutropenic mice (51% versus 23% for mice treated with pre-immune serum, P=0.04 by the logrank test), but not of non-neutropenic mice. There was no synergistic interaction between GTnAb and amphotericin B.
Conclusion: Our immunization strategy induced high titers of GTnAb in BALB/c mice. GTnAb had dissociated effects on fungal burden and survival rate in the murine IA models. Thus, GTnAb enhanced the survival rate of neutropenic mice without reducing tissue fungal burden, possibly through modulation of host angiogenesis and inflammatory response. These findings provide rationale for further efforts to produce GT monoclonal Abs

Abstract Number: P1087

Conference Year: 2013

Link to conference website: http://registration.akm.ch/einsicht.php?XNABSTRACT_ID=162748&XNSPRACHE_ID=2&XNKONGRESS_ID=180&XNMASK

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