HIV-1 initially assembles into an immature virus particle (left; schematic diagram and electron micrograph), which subsequently undergoes a series of changes that result in the assembly of a mature capsid core (top right). Wild-type integrase (yellow circles) plays a key role during maturation by forming tetramers that interact with the viral RNA (pink strands) and ensure that it is packaged inside the capsid. Class II mutant integrases cause aberrant maturation (bottom right) due to direct or indirect loss of the interaction between the enzyme and the viral RNA: this results in the production of an eccentric complex containing the viral RNA outside the capsid. In these eccentric particles, the location of the integrases and whether they form tetramers is not known.
Image credit: Figure modified from Kleinpeter and Freed, 2020 (CC BY 4.0).