Fiebig Stages

Fiebig stages are used to classify the progress of HIV infection, particularly in its early stages, which is relevant to cure because numerous studies strongly suggest that eradication is easier the earlier it is undertaken. The stages are shown in Table 2 below (derived from Figure 1 in “The immune response during acute HIV-1 infection: clues for vaccine development” AJ McMichael P Borrow GD Tomaras N Goonetilleke BF Haynes Nature Reviews Immunology 10 11-23 January 2010 and Figure 1 and Table 1 in “The Detection of Acute HIV Infection” MS Cohen CL Gray MP Busch FM Hecht Journal of Infectious Diseases 202 2010 Suppl 2: S271 & S272).

Fiebig StageCharacterization
(beginning of test)
Duration in
days (Range)
Eclipseundetectable10 (7 – 21)
IViral RNA+7 (5 – 10)
IIp24 antigen+5 (4 – 8)
IIIAntibody ELISA+3 (2 – 5)
IVWestern blot+ or -6 (4 – 8)
VWestern blot+ & integrase-70 (40 – 122)
VIWestern blot &, integrase+Open ended
Table 2. Fiebig stages, characterizations, and durations.

Note: Western blot is typically used as a confirmatory test for HIV infection; it uses electrophoresis to separate a purified antigen mixture into bands that correspond to the gp160, gp120, p66, p55, p51, gp41, p31, p24, p17, and p15 proteins (see the HIV Genome Glossary entry for descriptions of the proteins).