Table 3.

Currently Suggested “Core” Assays

Humoral assays

1. Plasma or serum anti-Env IgG binding antibody (if envelope is included in the vaccine)

• Percent responders

• Magnitude of response to the vaccine strain(s)

• Magnitude of response to circulating strains in proposed phase IIb trial population, preferably transmitted/founder strains

• Durability of response

• Specificity of response at peak immunogenicity time point [clade specificity, transmitted/founder vs. chronic, epitopes (linear and conformational, including V2)]

2. Plasma or serum anti-Env IgA binding antibody (if envelope is included in the vaccine)

• Percent responders

• Magnitude of response to vaccine strain(s)

• Durability of response

• Calculation of ratio anti-env IgG to anti-env IgA

3. HIV-1 neutralization

• Percent responders

• Magnitude of response to vaccine strain(s)

• Durability of neutralization against vaccine strain(s) and against circulating strains in proposed trial population; standard tier 1 and tier 2 panels of molecularly cloned viruses are recommended

4. ADCC against virus-infected cell targets (preferably the same subtype as circulating strains if not transmitted/founder strains from the proposed test regions)

• Assays that utilize virus-infected cell targets are preferred

Cellular assays

1. ICS or both ICS and ELISpot

• Percent responders: total, CD4+ T cells, CD8+ T cells

• Magnitude of response to vaccine

• Number and types of cytokines (minimum of three, preferably four)

2. Cellular proliferation in response to vaccine antigen(s) (CFSE cell staining)

• Percent responders

ADCC, antibody-dependent cellular cytotoxicity; ICS, intracellular cytokine staining; ELISpot, enzyme-linked immunosorbent spot; CFSE, carboxyfluoresceinsuccinimidyl ester.