Molecular/HIV laboratory

Real time PCR

Summary

Science

Clinical

Clinical

It is important to note that real time PCR plays no role in the initial diagnosis of HIV infection. Once a diagnosis has been made by other techniques, usually carried out in a virology department, viral load as determined by PCR becomes extremely important in monitoring disease progression. The viral load of a patient has a direct consequence on the number of functional CD4 T cells present because these are the cells in which the virus replicates and ultimately destroys. CD4 cells are crucial immune components in clearing infections so when they are depleted the individual gradually become more immunocompromised and more likely to get infections and other complications that are known as AIDS defining illnesses. At these late stages of HIV infection, it becomes very hard to retain low viral load levels. After an initial burst in the virus population with initial infection the numbers generally drop to low levels in patients on anti-retroviral therapy so after this individuals routinely have their viral load tested every 3 to 6 months. If a clinician notices that the viral load has destabilised and it is increasing they may need to change the anti-viral therapy that the patient is on to prevent depletion of CD4 cell populations.

Monitoring technologies like this and improvements in drug regimes have partly contributed to the greatly enhanced life expectancy of an HIV infected individual over the last 20 years.

• Science