Publications by authors named "Barry Bratcher"

Background: With an unplanned pregnancy rate of 50% or more in many countries, there is an urgent need for contraceptives that are more accessible and acceptable. To meet the growing demand for new contraceptives, ZabBio developed ZB-06, a vaginal film containing HC4-N, a human contraceptive antibody that inactivates sperm.

Objective: This study aimed to assess the potential contraceptive activity of the ZB-06 film using a surrogate assessment for contraceptive efficacy, the postcoital test.

View Article and Find Full Text PDF

The ongoing SARS-CoV-2 coronavirus pandemic of 2020-2021 underscores the need for manufacturing platforms that can rapidly produce monoclonal antibody (mAb) therapies. As reported here, a platform based on produced mAb therapeutics with high batch-to-batch reproducibility and flexibility, enabling production of 19 different mAbs of sufficient purity and safety for clinical application(s). With a single manufacturing run, impurities were effectively removed for a representative mAb product (the ZMapp component c4G7).

View Article and Find Full Text PDF

Stable, effective, easy-to-manufacture vaccines are critical to stopping the COVID-19 pandemic resulting from the coronavirus SARS-CoV-2. We constructed a vaccine candidate CoV-RBD121-NP, which is comprised of the SARS-CoV-2 receptor-binding domain (RBD) of the spike glycoprotein (S) fused to a human IgG1 Fc domain (CoV-RBD121) and conjugated to a modified tobacco mosaic virus (TMV) nanoparticle. In vitro, CoV-RBD121 bound to the host virus receptor ACE2 and to the monoclonal antibody CR3022, a neutralizing antibody that blocks S binding to ACE2.

View Article and Find Full Text PDF

We developed a SARS-CoV-2 vaccine candidate (CoV-RBD121-NP) comprised of a tobacco mosaic virus-like nanoparticle conjugated to the receptor-binding domain of the spike glycoprotein of SARS-CoV-2 fused to a human IgG1 Fc domain. CoV-RBD121-NP elicits strong antibody responses in C57BL/6 mice and is stable for up to 12 months at 2-8 or 22-28 °C. Here, we showed that this vaccine induces a strong neutralizing antibody response in K18-hACE2 mice.

View Article and Find Full Text PDF

Nonhormonal products for on-demand contraception are a global health technology gap; this unmet need motivated us to pursue the use of sperm-binding monoclonal antibodies to enable effective on-demand contraception. Here, using the cGMP-compliant -expression system, we produced an ultrapotent sperm-binding IgG antibody possessing 6 Fab arms per molecule that bind a well-established contraceptive antigen target, CD52g. We term this hexavalent antibody "Fab-IgG-Fab" (FIF).

View Article and Find Full Text PDF

Monoclonal antibodies (mAbs) hold great promise for treating diseases ranging from cancer to infectious disease. Manufacture of mAbs is challenging, expensive, and time-consuming using mammalian systems. We describe detailed methods used by Kentucky BioProcessing (KBP), a subsidiary of British American Tobacco, for producing high quality mAbs in a Nicotiana benthamiana host.

View Article and Find Full Text PDF

Recombinant subunit vaccines are an efficient strategy to meet the demands of a possible influenza pandemic, because of rapid and scalable production. However, vaccines made from recombinant hemagglutinin (HA) subunit protein are often of low potency, requiring high dose or boosting to generate a sustained immune response. We have improved the immunogenicity of a plant-made HA vaccine by chemical conjugation to the surface of the Tobacco mosaic virus (TMV) which is non infectious in mammals.

View Article and Find Full Text PDF

Ebola virus (EBOV) remains one of the most lethal transmissible infections and is responsible for high fatality rates and substantial morbidity during sporadic outbreaks. With increasing human incursions into endemic regions and the reported possibility of airborne transmission, EBOV is a high-priority public health threat for which no preventive or therapeutic options are currently available. Recent studies have demonstrated that cocktails of monoclonal antibodies are effective at preventing morbidity and mortality in nonhuman primates (NHPs) when administered as a post-exposure prophylactic within 1 or 2 days of challenge.

View Article and Find Full Text PDF

Filovirus infections can cause a severe and often fatal disease in humans and nonhuman primates, including great apes. Here, three anti-Ebola virus mouse/human chimeric mAbs (c13C6, h-13F6, and c6D8) were produced in Chinese hamster ovary and in whole plant (Nicotiana benthamiana) cells. In pilot experiments testing a mixture of the three mAbs (MB-003), we found that MB-003 produced in both manufacturing systems protected rhesus macaques from lethal challenge when administered 1 h postinfection.

View Article and Find Full Text PDF

Antibody-based products are not widely available to address many global health challenges due to high costs, limited manufacturing capacity, and long manufacturing lead times. There are now tremendous opportunities to address these industrialization challenges as a result of revolutionary advances in plant virus-based transient expression. This review focuses on some antibody-based products that are in preclinical and clinical development, and have scaled up manufacturing and purification (mg of purified mAb/kg of biomass).

View Article and Find Full Text PDF

Plants have been proposed as an attractive alternative for pharmaceutical protein production to current mammalian or microbial cell-based systems. Eukaryotic protein processing coupled with reduced production costs and low risk for mammalian pathogen contamination and other impurities have led many to predict that agricultural systems may offer the next wave for pharmaceutical product production. However, for this to become a reality, the quality of products produced at a relevant scale must equal or exceed the predetermined release criteria of identity, purity, potency and safety as required by pharmaceutical regulatory agencies.

View Article and Find Full Text PDF

To prevent sexually transmitted HIV, the most desirable active ingredients of microbicides are antiretrovirals (ARVs) that directly target viral entry and avert infection at mucosal surfaces. However, most promising ARV entry inhibitors are biologicals, which are costly to manufacture and deliver to resource-poor areas where effective microbicides are urgently needed. Here, we report a manufacturing breakthrough for griffithsin (GRFT), one of the most potent HIV entry inhibitors.

View Article and Find Full Text PDF