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Journal of Clinical Microbiology, November 2009, p. 3530-3539, Vol. 47, No. 11
0095-1137/09/$08.00+0 doi:10.1128/JCM.00673-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Multisite Comparison of Anti-Human Immunodeficiency Virus Microbicide Activity in Explant Assays Using a Novel Endpoint Analysis 
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Nicola Richardson-Harman,1,
Carol Lackman-Smith,1*
Patricia S. Fletcher,2
Peter A. Anton,3
James W. Bremer,4
Charlene S. Dezzutti,5
Julie Elliott,3
Jean-Charles Grivel,6
Patricia Guenthner,7
Phalguni Gupta,8
Maureen Jones,1
Nell S. Lurain,4
Leonid B. Margolis,6
Swarna Mohan,5
Deena Ratner,8
Patricia Reichelderfer,6
Paula Roberts,1
Robin J. Shattock,2 and
James E. Cummins Jr.1
Microbicide Quality Assurance Program, Southern Research Institute, Frederick, Maryland,1 Centre for Infection, Department of Cellular and Molecular Medicine, St. Georges University of London, London, United Kingdom,2 Center for Prevention Research, University of California, Los Angeles, California,3 Virology Quality Assurance Laboratory, Department of Immunology and Microbiology, Rush University Medical Center, Rush University, Chicago, Illinois,4 Magee-Women's Research Institute, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania,5 Program in Physical Biology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland,6 National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control, Atlanta, Georgia,7 Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania8
Received 2 April 2009/ Returned for modification 15 June 2009/ Accepted 6 August 2009
Microbicide candidates with promising in vitro activity are often advanced for evaluations using human primary tissue explants relevant to the in vivo mucosal transmission of human immunodeficiency virus type 1 (HIV-1), such as tonsil, cervical, or rectal tissue. To compare virus growth or the anti-HIV-1 efficacies of candidate microbicides in tissue explants, a novel soft-endpoint method was evaluated to provide a single, objective measurement of virus growth. The applicability of the soft endpoint is shown across several different ex vivo tissue types, with the method performed in different laboratories, and for a candidate microbicide (PRO 2000). The soft-endpoint method was compared to several other endpoint methods, including (i) the growth of virus on specific days after infection, (ii) the area under the virus growth curve, and (iii) the slope of the virus growth curve. Virus growth at the assay soft endpoint was compared between laboratories, methods, and experimental conditions, using nonparametric statistical analyses. Intra-assay variability determinations using the coefficient of variation demonstrated higher variability for virus growth in rectal explants. Significant virus inhibition by PRO 2000 and significant differences in the growth of certain primary HIV-1 isolates were observed by the majority of laboratories. These studies indicate that different laboratories can provide consistent measurements of anti-HIV-1 microbicide efficacy when (i) the soft endpoint or another standardized endpoint is used, (ii) drugs and/or virus reagents are centrally sourced, and (iii) the same explant tissue type and method are used. Application of the soft-endpoint method reduces the inherent variability in comparisons of preclinical assays used for microbicide development.
* Corresponding author. Mailing address: Southern Research Institute, 431 Aviation Way, Frederick, MD 21701. Phone: (301) 694-3232. Fax: (301) 694-7223. E-mail: lackmansmith{at}southernresearch.org
Published ahead of print on 2 September 2009.
Supplemental material for this article may be found at http://jcm.asm.org/.
Present address: Alpha StatConsult LLC, Damascus, MD.
Journal of Clinical Microbiology, November 2009, p. 3530-3539, Vol. 47, No. 11
0095-1137/09/$08.00+0 doi:10.1128/JCM.00673-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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