Reversetranscription PCR using a primer for an HIV gene can

Reverse-transcription PCR using a primer for an HIV gene can be used to amplify DNA for analysis. The Centers for Disease Control and Prevention (CDC) interviews the seven former patients to determine whether their histories show any additional risk factors for contracting HIV. Five out of the seven have no identified risk factors for HIV other than having had invasive procedures performed on them by Dr. B. The CDC then performs reverse-transcription PCR on DNA from white blood cells in Dr. B.\'s peripheral blood and the seven HIV-positive patients (see the figure). What can be concluded from the PCR amplification in the figure?

Solution

Am I even able to find out if the patients got HIV from the dentist?

HIV infection spreads thru the infected blood, Semen or biological fluids or by vaginal fluids. If the dentist has come in contact with the patient infected blood and gets in to his body otherthan oral route then there will be infection risk for the dentist.

Coming to the problem given in the image : Real-time PCR is a powerful technique compared to the basic PCR technique. The older PCR technique is basically qualitative with end point amplification products are visualized on gel-electrophoresis after PCR. End products show a lot of cross contamination and false positive results. On the other hand, Real-Time PCR is essentially quantitative method, which offers dynamic range of detection of the target nucleic acid during exponential phase of amplification. Through the use of appropriate fluorescent detection strategies in conjunction with proper instrumentation, all important starting amount of nucleic acid in the reaction can be accurately quantitated. Quantitation is achieved by measuring an increase in fluorescence during the exponential phase of PCR. in our present case taking blood from the white blood cells may not be the appropriate way to detect the viral loads. So they should have gone for RT PCR with fluorescence detection of plasma viral loads rather than WBCells and gel detection. Again another problem is the WBC DNA detection using the RT PCR. The RT PCR amplifies the viral RNA copies and not host DNA. This particular test is not appropriate and no conclusions can be drawn from the end test results.