Literature review > Issue 8 > Review on Bugli et al. 

This succinct, well written Note in Journal of Clinical Microbiology serves two purposes: one is to show the power of combinatorial phage libraries for translational research and the second is to present a new reagent of potential interest to clinical virologists. Combinatorial phage display libraries have been used for over a decade to find the biological needle in a haystack in terms of selecting and displaying biologically important ligands including high affinity human antibodies against pathogen targets of interest [1]. Such antibodies can be used directly in therapeutic applications or indirectly as carriers in targeted therapy [2]. Alternatively, as described here, the selected human antibody, once "checked out" of the phage display library can be used to produce a diagnostic reagent.

In this study, the authors panned the library against the HSV-2 virus's glycoprotein G2 with a low-tech but effective preadsorption step with HSV-1 to enhance the selection of phages carrying the HSV-2 specific antibodies. The gene encoding the phage coat protein (and its human Fab antibody fragment cargo) was then incorporated into an E. coli expression system. Resulting recombinant Fabs were tested by ELISA, then by indirect fluorescent antibody methods for their reactivity to gG-2. Returning to the high tech arena, the authors then sequenced the heavy-chain variable domains (an unthinkable challenge only a few years ago) then purified one clone for "real-world" testing as a diagnostic reagent.

It's oddly reassuring to note that a number of steps in this work use techniques that are so well established as to be considered "classical" virology methods for antibody reactivity and specificity: indirect FA, ELISA, immunoaffinity protein purification, and competitive ELISA.

The reagent resulting from this interesting development process has been offered as an alternative to mouse monoclonal antibodies for the typing of clinical isolates of HSV-2 in cell culture. It appears to work quite well although head-to-head comparisons with commercial reagents were not reported. The irony of this elegant work is that in the rapidly changing world of diagnostic virology, typing reagents based on antigen-antibody binding will likely be out of date in a few years-supplanted by DNA amplification and sequencing methods that rapidly, even robotically, can identify, quantify and type HSV-1 and HSV-2 directly from specimens. The HSV culture "library" will close before we know it, but HSV infections likely will command attention beyond that time. Work of Bugli and colleagues reminds us that molecular maneuvers can buff up the classic tests that are still in wide use while propelling the field to more cost-effective and rapid diagnostic applications.

References: 

1. Noren KA and Noren CJ. Construction of high-complexity combinatorial phage display peptide libraries. 2001, Methods:23:169-178.

2. Andrews A, Bradley D, Lackritz B. http://www.cancerlinks.com/monoclonal.html

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