Human Antibodies

BACKGROUND: Antibodies for human clinical applications are predominantly produced in mammalian expression systems, with Chinese hamster ovary (CHO) cells being the gold standard. CHO cells are ideal for the manufacturing of the IgG class of antibodies, but not for the production of complex antibodies like secretory IgAs (SIgAs) and IgMs, which remain unavailable for clinical use. In contrast, plant seeds and leaves hold the promise to produce SIgAs, IgMs and similar complex antibody formats to scalable amounts. Using transient transformation of Nicotiana benthamiana leaves, complex antibody formats can be produced up to milligram amounts in less than a month.

OBJECTIVE: Based on these merits, we propose a model for early-phase exploration and designing of innovative antibody formats for therapeutic application. Further in this essay, we elaborate how the model was followed during the selection of novel antibodies for seed-based production.

RESULT: This exploratory model led to the engineering of novel light-chain devoid porcinized-llama antibodies (VHH-Fc) of the IgG (VHH-IgG) and IgA (VHH-IgA) isotypes and also tetravalent dimeric and SIgAs.

CONCLUSION: The proposed strategy may lead to plant-based rapid engineering of innovative antibodies more apt and efficacious for therapy, and in the coarse also add to the understanding of their mode of action.

Human immunoglobulins circulate as highly heterogeneously glycosylated mixture of otherwise homogeneous protein backbones. A series of studies, mainly on IgG, have unequivocally proven that antibodies modulate their effector function through sugars present in the Fc domain. However, our limited technology in producing complex proteins such as antibodies, with defined glycan structures hamper in depths studies. This review introduces a plant based expression platform enabling engineering of antibody glycans. The procedure is based on the simultaneous delivery of appropriate constructs, carrying cDNAs of target proteins (e.g. heavy and light chain of antibodies) in combination with human glycosylation enzymes into plant leaves. Harvesting of recombinant proteins one week post construct delivery allows high speed and flexibility. Major achievements include the production of functional active slialylated pentameric IgMs in tobacco leaves. The system provides a viable approach to the generation of antibodies with defined glycoforms on demand, contributing to studies on antibody glycans and the development of novel antibody based drugs.

This review describes the history of Ebola monoclonal antibody (mAb) development leading up to the recent severe Ebola outbreak in West Africa. The Ebola virus has presented numerous perplexing challenges in the long effort to develop therapeutic antibody strategies. Since the first report of a neutralizing human anti-Ebola mAb in 1999, the straightforward progression from in vitro neutralization resulting in in vivo protection and therapy has not occurred. A number of mAbs, including the first reported, failed to protect non-human primates (NHPs) in spite of protection in rodents. An appreciation of the role of effector functions to antibody efficacy has contributed significantly to understanding mechanisms of in vivo protection. However a crucial contribution, as measured by post-exposure therapy of NHPs, involved the comprehensive testing of mAb cocktails. This effort was aided by the use of plant production technology where various combinations of mAbs could be rapidly produced and tested. Introduction of appropriate modifications, such as specific glycan profiles, also improved therapeutic efficacy. The resulting cocktail, ZMapp™, consists of three mAbs that were identified from numerous mAb candidates. ZMapp™ \ is now being evaluated in human clinical trials but has already played a role in bringing awareness to the potential of antibody therapy for Ebola.

BACKGROUND: Hepatitis B (HB) is a serious global public health problem that put health professionals particularly at risk.

OBJECTIVE: The aim of this study was to investigate the prevalence of Hepatitis B surface antigen (HBsAg) among Biomedical Students of African descent attending Usmanu Danfodiyo University Sokoto in North-Western Nigeria.

METHODS: The Onsite HBsAg (CTK Biotech, USA) was used to detect the presence of hepatitis B surface antigen.

RESULTS: We tested 186 consecutively-recruited students consisting of 147 males and 39 females aged 18-35 years (mean age 26 ± 2.0 years). Of the 186 students tested, 25 (13.4%) were positive for HBsAg. The prevalence of HBsAg was significantly higher among students in the 21-25 years age group. Hepatitis B vaccination uptake among students was 7%. Majority of subjects were single 173(93.1%) compared to married 13(6.9%). Ethnic distribution of the subjects indicated that 104(55.9%) were Hausa compared to Yoruba 32 (17.2%), other ethnic groups 21(11.3%), Fulani 20(10.8%) and Igbo 9(4.8%).

CONCLUSIONS: This study indicates a high prevalence of hepatitis B virus infection among Biomedical students in Sokoto, North Western, Nigeria. Finding from this study is enough justification for the implementation of a policy to routinely test students entering into the biomedical professions for Hepatitis B virus infection. There is the need to provide hepatitis B vaccination universally to all those who are found negative prior to commencement of their biomedical training. There is also need to educate students entering biomedical professions and healthcare workers on the modes of transmission and prevention, importance of being compliant with protective vaccination as well as the need to observe universal precaution and infection control guidelines during their training and future professional practice.

Monoclonal antibodies (mAbs) are the leading class of targeted therapeutics and remarkably effective in addressing autoimmune diseases, inflammations, infections, and various types of cancer. Several mAbs approved by US food and drug administration (FDA), are available on the market and a number are pending for approval. Luckily, FDA approved mAbs have played a pivotal role in the treatment and prevention of lethal diseases. However, claiming that licensed mAbs are 100% safe is still debatable, because infections, malignancies, anaphylactoid, and anaphylactic reactions are the more frequently associated adverse events. To evaluate benefit to risk ratio of mAbs, it is important for the clinical research staff or physicians to monitor and follow-up the patients who are receiving mAbs dozes. It is recommended that patients, physicians, biopharmaceutical companies, and researchers should keep in touch to highlight and resolve antibody-based adverse events. In this review we underscore the associated challenges of mAbs, approved by FDA from 2007-2014.

BACKGROUND: Tetanus neurotoxin (TeNT) is composed of a light (LC) and heavy chain (HC) polypeptides, released by anaerobic bacteriumClostridium tetani and can cause fatal life-threatening infectious disease. Toxin HC and LC modules represents receptor binding and zinc metalloprotease activity, respectively. The passive administration of animal-derived antibodies against tetanus toxin has been considered as the mainstay therapy for years. However, this treatment is associated with several adverse effects due to the presence of anti-isotype antibodies.

OBJECTIVE: In the present study, we have produced the fully human single chain antibody fragments (HuScFv) from two human antibody phage display libraries.

MATERIAL AND METHODS: Twenty-four different HuscFvs were isolated from two anti TeNT immune libraries. Our produced human ScFv (HuScFv) were converted to IgG platform and analyzed regarding their specific reactivity to TeNT.

RESULTS: All of the selected scFvs have the same VL but different VH. Three HuscFvs from the first library (TTX15, 51, 75) and two HuscFvs from the second library (TTX16, 20) were chosen to convert to IgG1 using pOptiVEC and pcDNA3.3 systems. Production of IgG1 from transfected DG44 and binding capacity of them to tetanus toxin and toxoid were measured by ELISA. ELISA results showed no detectable production of TTX16 and TTX20 IgG1. Although, TTX51 and TTX75 were converted and produced as IgG1, no reactivity to tetanus toxin and toxoid was observed. However, TTX15 was successfully produced as whole IgG1 platform with reactivity to both tetanus toxin and toxoid. The latter would be an appropriate replacement for conventional polyclonal antibodies if would meet the further characterization including specificity determination, affinity measurement and toxin neutralizing assays.

CONCLUSION: Our results demonstrated production of functional IgG1 derived from TTX15 scFv and might be an appropriate replacement for polyclonal Tetabulin but it needs further characterization.