Fasciola hepatica:development of monoclonal antibodies against somatic antigens and their characterization by ultrastructural localization of antibody binding

A series of monoclonal antibodies was prepared against tegumental and internal antigens of Fasciola hepatica by immunizing mice with whole adult-fluke homogenates prior to harvesting the splenic lymphocytes for fusion. Preliminary screening by the Indirect Fluorescent Antibody technique indicated the occurrence of discrete groups of monoclonals differing from one another in tissue-specificity but within which IFA labelling patterns were fairly consistent. Representative hybridomas for 5 of these groups were stabilized and used to produce ascites fluid in mice. By application of an immunogold labelling technique it was possible to map the distribution of antigens for which each monoclonal antibody had affinity throughout the tissues of 4-week and 12-week flukes. Several monoclonals specifically labelled antigenic determinants on the important tegumental antigen T1. However the distribution of gold colloid labelling suggested that epitopes other than that normally exposed to the infected host were recognized; and several monoclonals specifically attached to T1 antigen in the tegument of juvenile worms only. The glycocalyx of the gut and excretory system of flukes shared T1 antigenicity with the tegument. Monoclonal antibodies were produced against an internal immunogen associated with ribosomes and heterochromatin in active protein-producing cells, and against interstitial material of adult flukes. Monoclonals against antigens in parenchymal cell cytoplasm and in mature vitelline cells were recognized but the corresponding hybridomas were not stabilized.

Generation and Characterization of ALX-0171, a Potent Novel Therapeutic Nanobody for the Treatment of Respiratory Syncytial Virus Infection

Respiratory Syncytial Virus (RSV) is an important causative agent of lower respiratory tract infections in infants and elderly. Its fusion (F) protein is critical for virus infection. It is targeted by several investigational antivirals and by palivizumab, a humanised monoclonal antibody used prophylactically in infants considered at high risk of severe RSV disease. ALX-0171 is a trimeric Nanobody that binds the antigenic site II of RSV F-protein with subnanomolar affinity. ALX-0171 demonstrated superior in vitro neutralisation compared to palivizumab against prototypic RSV A and B strains. Moreover, ALX-0171 completely blocked replication below limit of detection in 87% of the viruses tested versus 18% for palivizumab at a fixed concentration. Importantly, ALX-0171 was highly effective in reducing both nasal and lung RSV titers when delivered prophylactically or therapeutically directly to the lungs of cotton rats. ALX-0171 represents a potent novel antiviral compound with significant potential to treat RSV-mediated disease.