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Author's response to Drs. Preiser, Drexler and Drosten

Posted by plosmedicine on 31 Mar 2009 at 00:02 GMT

Author: Susan Fiscus
Position: Professor, Department of Microbiology & Immunology
Institution: University of North Carolina at Chapel Hill
Submitted Date: November 20, 2006
Published Date: November 20, 2006
This comment was originally posted as a “Reader Response” on the publication date indicated above. All Reader Responses are now available as comments.

We thank Drs. Preiser, Drexler and Drosten for their letter and share their concerns regarding HIV-1 viral load assays in resource limited settings. The real time RT-PCR assay they have developed had not yet been published when our review was submitted or revised. As noted in Table 1 of our review, many of the current viral load assays require additional evaluation with different subtypes and others may underestimate non-B subtypes. In addition, under the heading "What is needed for implementation of simplified viral load testing?" we state "First, each country must determine if the assay will quantify subtypes common in the region and is appropriate for the technical staff and laboratory equipment available."

In-house assays require production, optimization, validation, and quality assurance of all reagents which is challenging in any circumstances, and would be extremely difficult in laboratories in most resource limited settings. Real-time PCR instruments are expensive and maintenance in many places would be a problem. What is really needed is a technologically much simpler, much less expensive, perhaps semi-quantitative assay for measuring viral load.

Susan A. Fiscus, Ph.D.
Department of Microbiology & Immunology
University of North Carolina at Chapel Hill
Chapel Hill, North Carolina

Competing interests declared: As stated in original article: "No member of the writing team owned stock or was employed by the kit manufacturers mentioned in this article. Some free kits and the loan of equipment were provided by manufacturers for evaluation of the assays and for training purposes: SF received three p24 kits and two Cavidi kits as well as the loan of an ELISA reader from PerkinElmer; SC received two p24 kits, six Cavidi kits, and the loan of an ELISA reader from Cavidi; CJ received two Cavidi kits; WS received two Cavidi kits and the loan of an ELISA reader from PerkinElmer. In addition, SC received partial support from Cavidi to attend the 3rd International AIDS Society Conference in Rio de Janeiro, Brazil, 2005. Some members of the Forum for Collaborative HIV Research Alternative Viral Load Assay Working Group were employed by manufacturers, and they are listed in the Acknowledgments."