Table 2.

Stages of Preclinical Microbicide Development

Stage 1: In vitro efficacy and toxicity assays

Efficacy versus CCR5-tropic virus strains

PBMC efficacy and toxicity assays (clinical subtypes B, C, and/or E)

Efficacy in monocytes and dendritic cells

Efficacy in presence of mucin

Efficacy in presence of synthetic vaginal fluid and seminal plasma

Efficacy at vaginal pH

Stage 2: Transmission inhibition assays

Cell-free and cell-associated virus transmission assays

CD4-dependent and CD4-independent transmission assays

Transmission inhibition and sterilization assay (MTSA)

Stage 3: Mechanistic assays

Attachment inhibition

Fusion inhibition

Virus inactivation assays (virucidal activity)

RT inhibition assays

CCR5 and CXCR4-tropism for attachment inhibitors

DC-SIGN inhibition assay for attachment inhibitors

gp120/CD4 ELISA

Stage 4: Range of action assays

Efficacy against range of HIV-1 subtypes (clades)

Efficacy against CCR5- and CXCR4-tropic viruses

Efficacy against resistant viruses

Efficacy against HIV-2, SIV, and SHIV

Efficacy versus other STIs

Step 5: Vaginal/Rectal Environmental Toxicity

Toxicity to Lactobacillus sp.

MatTek epivaginal assays

Vaginal cell toxicity

Cervical cell toxicity

Rectal cell toxicity

Step 6: Combination assays with other potential microbicides

In attachment assay

In standard PBMC assays

In transmission/sterilization assay

Step 7: Resistance

Transmission of resistant strains in attachment assay

Selection of resistant strains in microbicide-like conditions

Step 8: Cervical explant or other ex vivo model

Step 9: Activity in candidate gel formulations

Step 10: Non-human primate models/Mouse models