Frequently Asked Questions - Concentrated Viral Preparations

Generally, ABI recommends the following virus preparations for the applications listed:

• ELISA/Western blotting: Purified virus or purified viral lysate.
• Infectivity Assays and in vitro applications: Direct-pelleted or purified virus.
• Lymphocyte stimulation assays: Custom prepared and inactivated purified virus.
• Virus tropism/binding studies: Purified virus or custom prepared and inactivated purified virus.

"Purified Viral Lysate" indicates a gradient purified virus preparation that has been partially or completely lysed and solubilized by detergent treatment, coupled with additional post-lysis treatment steps to increase purity and/or enhance inactivation efficiency.

Viral lysates are inactivated, and inactivation is confirmed by cell culture infectivity assays.

For HIV-1 IIIB, "single-banded" gradient purified virus will yield the following relative distribution of virus specific antigens: p24: 8-15% of total protein gp120: 0.10 - 1.0% of total protein gp160: 0.10 - 1.0% of total protein

Although PAGE/Western blot is part of our QC regimen, as a routine, ABI does not provide SDS-PAGE and Western blot profiles on our viral antigens.

As a rule, it is not advisable to equate p24 or reverse transcriptase activity in terms of infectious equivalents for HIV, unless repeated infectivity assays of the same stock are performed and correlated with p24 or RT levels. Although the relative p24 or reverse transcriptase activity is positively correlated with virus infectivity in most cases, a true measure of virus infectivity (i.e., TCID₅₀, plaque assay, LD₅₀) as the basis for R & D is the most appropriate way to ensure reproducibility of results.