Expression and identification of recombinant soluble single-chain variable fragment of monoclonal antibody MC3

Phage Display-Derived Cross-Reactive Neutralizing Antibody against Enterovirus 71 and Coxsackievirus A16

Enterovirus 71 (EV71) and coxsackievirus A16 (CVA16) are members of the Picornaviridae family and are considered the main causative agents of hand, foot and mouth disease (HFMD). In recent decades large HFMD outbreaks caused by EV71 and CVA16 have become significant public health concerns in the Asia-Pacific region. Vaccines and antiviral drugs are unavailable to prevent EV71 and CVA16 infection. In the current study, a chimeric antibody targeting a highly conserved peptide in the EV71 VP4 protein was isolated by using a phage display technique. The antibody showed cross-neutralizing capability against EV71 and CVA16 in vitro. The results suggest that this phage display-derived antibody will have great potential as a broad neutralizing antibody against EV71 and CVA16 after affinity maturation and humanization.

Dendritic cells transfected with scFv from Mab 7.B12 mimicking original antigen gp43 induces protection against experimental Paracoccidioidomycosis

Paracoccidioidomycosis (PCM), endemic in Latin America, is a progressive systemic mycosis caused by Paracoccidioides brasiliensis (P. brasiliensis), which primarily attacks lung tissue. Dendritic cells (DCs) are able to initiate a response in naïve T cells, and they also participate in Th-cell education. Furthermore, these cells have been used for therapy in several disease models. Here we transfected DCs with a plasmid (pMAC/PS-scFv) encoding a single chain variable fragment (scFv) of an anti-Id antibody that is capable of mimicking gp43, the main antigenic component of P. brasiliensis. First, Balb/c mice were immunized subcutaneously with pMAC/PS-scFv and, after seven days, scFv protein was presented to the regional lymph nodes cells. Moreover, we showed that the DCs transfected with scFv were capable of efficiently activating proliferation of total lymph node cells and inducing a decrease in lung infection. Therefore, our results suggested that the use of scFv-transfected DCs may be a promising therapy in the paracoccidioidomycosis (PCM) model.

Bird's-eye view on gastric cancer research of the past 25 years

This paper provides a bird's-eye view of our 25-year research work on gastric cancer, including both exploration of pathogenesis and preclinical or clinical applications of diagnosis and treatment. Although there have been achievements and reasons for applause, there are, nonetheless, more failings and teachings. Some problems that we experienced 25 years ago are still problems we have to face today. We are absolutely not singing the same old tune. Looking back makes us wiser and our way smoother. Although it is a long and arduous way to further study gastric cancer, we are willing to devote ourselves to it.

Construction, expression and tumor targeting of a single-chain Fv against human colorectal carcinoma

AIM: A single-chain antibody fragment, ND-1scFv, against human colorectal carcinoma was constructed and expressed in E.coli, and its biodistribution and pharmacokinetic properties were studied in mice bearing tumor.

METHODS: V_H and V_L genes were amplified from hybridoma cell IC-2, secreting monoclonal antibody ND-1, by RT-PCR, and connected by linker (Gly₄Ser)₃ to form scFv gene, which was cloned into expression vector pET 28a(+) and finally expressed in E.coli. The expressed product ND-1scFv was purified by metal affinity chromatography using Ni-NTA, its purity and biological activity were determined using SDS-PAGE and ELISA. ND-1scFv was labeled with ^99mTc, and then injected into mice bearing colorectal carcinoma xenograft for phamacokinetic study in vivo.

RESULTS: SDS-PAGE analysis showed that the relative molecular weight of recombinant protein was 30 kDa with purity of 94%. ELIAS assay revealed that ND-1scFv retained the immunoactivity of parent mAb, being capable of binding specifically to human colorectal carcinoma cell line expressing associated antigen. Radiolabeled ND-1scFv exhibited rapid tumor targeting, with specific distribution in mice bearing colorectal carcinoma xenograft observed as early as 1 h following injection. In vivo pharmacokinetic studies also demonstrated that ND-1scFv had very rapid plasma clearance (T_1/2α of 5.7 min, T_1/2β of 2.6 h).

CONCLUSION: ND-1scFv shows significant immunoactivity, and better pharmacokinetic and biodistribution characteristics compared with intact mAbs, demonstrating the possibility as a carrier for tumor-imaging.