A hollow-fiber bioreactor for expanding HIV-1 in human lymphocytes used in preparing an inactivated vaccine candidate

Applications of the hollow-fibre infection model (HFIM) in viral infection studies

Conventional cell culture systems involve growing cells in stationary cultures in the presence of growth medium containing various types of supplements. At confluency, the cells are divided and further expanded in new culture dishes. This passage from confluent monolayer to sparse cultures does not reflect normal physiological conditions and represents quite a drastic physiological change that may affect the natural cell physiobiology. Hollow-fibre bioreactors were in part developed to overcome these limitations and since their inception, they have widely been used in production of monoclonal antibodies and recombinant proteins. These bioreactors are increasingly used to study antibacterial drug effects via simulation of in vivo pharmacokinetic profiles. The use of the hollow-fibre infection model (HFIM) in viral infection studies is less well developed and in this review we have analysed and summarized the current available literature on the use of these bioreactors, with an emphasis on viruses. Our work has demonstrated that this system can be applied for viral expansion, studies of drug resistance mechanisms, and studies of pharmacokinetic/pharmacodynamic (PK/PD) of antiviral compounds. These platforms could therefore have great applications in large-scale vaccine development, and in studies of mechanisms driving antiviral resistance, since the HFIM could recapitulate the same resistance mechanisms and mutations observed in vivo in clinic. Furthermore, some dosage and spacing regimens evaluated in the HFIM system, as allowing maximal viral suppression, are in line with clinical practice and highlight this 'in vivo-like' system as a powerful tool for experimental validation of in vitro-predicted antiviral activities.

Derivation of non-infectious envelope proteins from virions isolated from plasma negative for HIV antibodies

Natural membrane-bound HIV-1 envelope proteins (mHIVenv) could be used to produce an effective subunit vaccine against HIV infection, akin to effective vaccination against HBV infection using the hepatitis B surface antigen. The quaternary structure of mHIVenv is postulated to elicit broadly neutralizing antibodies protective against HIV-1 transmission. The founder virus transmitted to infected individuals during acute HIV-1 infection is genetically homogeneous and restricted to CCR5-tropic phenotype. Therefore, isolates of plasma-derived HIV-1 (PHIV) from infected blood donors while negative for antibodies to HIV proteins were selected for expansion in primary lymphocytes as an optimized cell substrate (OCS). Virions in the culture supernatants were purified by removing contaminating microvesicles using immunomagnetic beads coated with anti-CD45. Membrane cholesterol was extracted from purified virions with beta-cyclodextrin to permeabilize them and expel p24, RT and viral RNA, and permit protease-free Benzonase to hydrolyze the residual viral/host DNA/RNA without loss of gp120. The resultant mHIVenv, containing gp120 bound to native gp41 in immunoreactive form, was free from infectivity in vitro in co-cultures with OCS and in vivo after inoculating SCID-hu Thy/Liv mice. These data should help development of mHIVenv as a virally safe immunogen and enable preparation of polyclonal hyper-immune globulins for immunoprophylaxis against HIV-1 infection.

Optimization manufacture of virus- and tumor-specific T cells

Although ex vivo expanded T cells are currently widely used in pre-clinical and clinical trials, the complexity of manufacture remains a major impediment for broader application. In this review we discuss current protocols for the ex vivo expansion of virus- and tumor-specific T cells and describe our experience in manufacture optimization using a gas-permeable static culture flask (G-Rex). This innovative device has revolutionized the manufacture process by allowing us to increase cell yields while decreasing the frequency of cell manipulation and in vitro culture time. It is now being used in good manufacturing practice (GMP) facilities for clinical cell production in our institution as well as many others in the US and worldwide.

Antiviral pharmacodynamics in hollow fibre bioreactors

Pharmacodynamic investigation of antiviral compounds studies the relationship between drug exposure and the virological response. These studies are usually performed in animals and, eventually, in humans and are a very expensive proposition. To find a more efficient and less expensive method for determining pharmacodynamics of antiviral and antimicrobial compounds, the hollow fibre infection model (HFIM) system was developed to perform pharmacodynamic studies in vitro. This review covers the authors' studies on the use of in vitro hollow fibre bioreactor technologies for determining the pharmacodynamics of antiviral compounds for viruses grown in cultured cells, including HIV grown in CD4+ lymphoblastoid cells, vaccinia viruses grown in HeLa-S3 cells and influenza viruses grown in Madin-Darby canine kidney cells. Where possible, correlations between the pharmacodynamic index derived from the in vitro HFIM systems and clinical pharmacodynamic studies are made.

Participating in the evolution of transfusion medicine from a dispensary into a discipline

Collecting, processing and dispensing blood for hemotherapy has evolved into transfusion medicine (TM), a newly recognized discipline. Joining my efforts to those of collaborators all over the world during this period of transformation, my scientific career spanned from the investigation of the immunogenetics of Bombay (OhOh) blood to the establishment of the academic TM program at the University of California, San Francisco (UCSF) (San Francisco, Calif). The twin discoveries of class-specific antibodies against immunoglobulin A (IgA) causing anaphylactic transfusion reactions and of anti-IgA of limited specificity defining A2m(1) as the first genetic marker of IgA led to the award of the Julliard Prize. My precocious appointment as the head of the Bombay Municipal Blood Center in India launched my academic career in 1969 as the Chief of the blood bank at UCSF Medical Center. Viral hepatitis, then the principal risk of transfusion, engaged me in the molecular analyses of purified hepatitis B virus (HBV) and its surface antigen. Consequently the first HBV vaccine, derived from infected plasma (superseded by cloned HBV envelope protein) and hepatitis B immune globulin were developed for clinical trials that led to Food and Drug Administration-licensed biologic products for prophylaxis and therapy. The advent of HIV/AIDS in the early 1980s raised renewed concern about transfusion safety and led me to push for hepatitis B core antibodies blood screening for improved transfusion safety. The triennial International Symposia on Viral Hepatitis and Liver Disease, which I started in 1972, continue to be the foremost forum for the contemporary assessment of hepatitis prevention and treatment. Besides viral hepatitis, I undertook multiplexed flow cytometric analyses for markers of infection by blood-borne viruses and their polymerase chain reaction-amplified gene products, kinetics of HIV replication in peripheral blood lymphocytes, leukocyte depletion for safer transfusion, and removal/inactivation of blood-borne viruses. The TM training and research programs I initiated at UCSF in the 1980s with National Institutes of Health support enabled me to recruit new faculty members who continue to foster the worldwide advancement of transfusion safety.