Joann Vennari

Genetic and Immunologic Characterization of Viruses Infecting MN-rgp120-Vaccinated Volunteers

Proviral sequences were determined and immunologic characterization was carried out for envelope glycoproteins from 7 vaccinees who became infected with human immunodeficiency virus type 1 (HIV-1), through high-risk behavior, while participating in clinical trials of MN-rgp120, a candidate HIV-1 vaccine. All 7 infections resulted from subtype B viruses; however, only 3 of the viruses possessed the MN serotype-defining V3 domain sequence, IGPGRAF, prevalent in 60%-70% of US infections. Six of the 7 viruses differed from MN-rgp120 at a neutralizing epitope in the C4 domain, and all 7 differed from MN-rgp120 at a neutralizing epitope in the V2 domain. Recombinant gp120 was prepared from each breakthrough specimen and tested for binding to a panel of neutralizing monoclonal antibodies. The results suggest that 6 of 7 breakthrough infections may be related to incomplete immunization or to infection with viruses that differed from the vaccine immunogen at important virus-neutralizing epitopes.

Development and Qualification of a Novel Virus Removal Filter for Cell Culture Applications

Commercial bioreactors employing mammalian cell cultures to express biological or pharmaceutical products can become contaminated with adventitious viruses. The high expense of such a contamination can be reduced by passing all gases and fluids feeding the bioreactor through virus inactivation or removal steps, which act as viral barriers around the bioreactor. A novel virus barrier filter has been developed for removing viruses from serum‐free cell culture media. This filter removes the 20 nm minute virus of mice by >3 log reduction value (LRV), the 28 nm bacteriophage ΦX174 by >4.5 LRV, the mycoplasma Acholeplasma laidlawii by ≥8.8 LRV, and the bacteria Brevundimonas diminuta by ≥9.2 LRV. Robust removal occurs primarily by size exclusion as demonstrated over a wide range of feedstocks and operating conditions. The filtered media are indistinguishable from unfiltered media in growth of cells to high densities, maintenance of cell viability, and productivity in expressing protein product. Insulin and transferrin show high passage through the filter. The virus barrier filter can be autoclaved. The relatively high membrane permeability enables the use of a moderate filtration area.