Keywords: HIV, AIDS, LTR, Diagnostic, Resistance, Drug, Anti-Retroviral, Tropism
US patent #6797464, 7232657 & other patents pending
It is estimated that in untreated AIDS patients, 10 billion
viruses are produced daily, & 100 million new cells are
infected. Of the 10 billions new viruses, 1/1000 (10 million) will
harbor a mutation some of which will make HIV resistant to
antiretroviral therapy. In patient on anti-retroviral drug therapy,
drug selection pressure facilitates complete replacement of the
wild type virus to occur in 14-28 days. Early intervention &
detection of drug resistance in untreated & treated patients are
vital to reduce the rate of emergence & spread of drug
resistant HIV & limit its adverse impact on public health. Ultra
sensitive assays that can identify drug resistance mutation &
viral tropism early in viral lifecycle are critical to accomplish this
outcome.
UMass Medical School investigator Dr. Mario Stevenson &
colleagues have developed a highly sensitive assay that can
predict the onset of drug resistance before patients fail
antiretroviral drug therapy. The PCR based assay detects
intracellular HIV genetic material, specifically circular DNA
containing two LTRs (2-LTR). This assay is based on the
discovery that 2-LTR circles are found in patients undergoing
drug therapy who have undetectable serum virus levels. The 2LTR circles are a labile intermediate in HIV life cycles & the
presence of the same in patients indicates the persistence of
HIV. Because of their unique structure, 2-LTR circles can be
selectively & specifically identified from the background of
defective & latent viral genomes. Further, drug resistant
mutations, which occur at very low frequencies in a sea of
drug-naïve genotypes, are overrepresented in 2-LTR circles.
Table
 Ultra-Sensitive Assay: The 2-LTR assay can detect up to 1
molecule or 2LTR circle per million PBMCs. In a head to
head comparison, the 2-LTR assay displayed superlative
sensitivity in HIV detection over a serum viral load assay.
 Sensitive Detection Equals Early Intervention: The 2-LTR
assay can detect HIV presence in patients with undetectable
cell free RNA in serum. This assay may detect HIV early in
the infection process and hence may be used for regular and
or confirmatory HIV screening. Early detection & drug
therapy will decrease viral transmission & mortality rates.
 Low Sample Volume: Because of its superior sensitivity
very low sample volumes are required for detecting HIV
infected cells (0.1 to 1ml of whole blood).
 Early Drug Resistant Detection: In patients on antiretroviral
therapy, the 2-LTR assay identified a resistance mutation 36
weeks before viremia, an event associated with failed drug
therapy. Early detection of drug resistance will help
physicians make patient specific changes in drug regimen.
 Identify Virus Tropism: The 2-LTR assay can ascertain
viral tropism in patients. This knowledge may help in
designing patient specific drug regimens since certain drugs
such as CCR5 inhibitors work by inhibiting only a subset of
viral strains.
 Evaluate Treatment Efficacy & Course: A physician’s
decision to continue a patient on HIV drug therapy is often
based on serum viral load. However, the decisions may be
misguided because of a lack of a sensitive assay for
detecting HIV presence. Investigations revealed that the 2LTR circle assay can identify HIV–infected blood cells in
patient with no detectable plasma virus indicating that these
patients should continue HIV treatment.
 Market Potential: According to CDC estimates ~16-22
million persons in the United States are tested for HIV each
year.
UMass OTM is seeking statements of interest from parties
interested in licensing and/ or sponsoring collaborative
research to commercialize this technology.
Superior sensitivity of 2-LTR circle over a standard serum virus
detection assay in several patient samples
Satinder S. Rawat, PhD
Licensing Officer
UMass Medical School
Office of Technology Management
Phone: (508) 856-6686; Fax: (508) 856-1482
E-mail: Satinder.Rawat@umassmed.edu
HIV/AIDS diagnostics
UMMC 099-25& UMMC 08-36