radiotherapy

Treatment using radium or other radioactive matter.

randomisation

The process of selecting by chance the treatment that a clinical trial participant will receive.

recombinant

(ree-kom-bin-nant)

Genetically reconstructed.

rectum

(rek-tum)

The last part of the large intestine just above the anus.

regimen

A drug or treatment combination and the way it is taken.

regression

Improvement in a tumour.

remission

(ree-mish-un)

Partial recovery from an illness, an alternative word for regression.

renal

(ree-null)

Relating to the kidneys.

replication

(re-pli-kay-shun)

The process of viral reproduction.

resistance

A drug-resistant HIV strain is one which is less susceptible to the effects of one or more anti-HIV drugs because of its genotype.

retinitis

(ret-tin-eye-tuss)

Damage to the retina, the light-sensitive surface at the back of the eye.

retrovirus

(ret-tro-vy-russ)

Family of viruses to which HIV belongs, that are distinguished by their use of RNA.

reverse transcriptase

A retroviral enzyme which converts genetic material from RNA into DNA, an essential step in the lifecycle of HIV.

RNA

Ribonucleic acid, the form in which HIV stores its genetic material.