Comparison of the reactivities of baculovirus-expressed recombinant Norwalk virus capsid antigen with those of the native Norwalk virus antigen in serologic assays and some epidemiologic observations

Abstract

Since the discovery of the Norwalk virus (NV) by immune electron microscopy (IEM) in 1972, serologic studies with this virus have relied on particle-positive fecal material from infected volunteers as the source of antigen because it has not been possible to propagate this virus in cell culture. However, the recent cloning of the NV (strain 8FlIa) genome and expression of the capsid protein in a baculovirus system to form "virus-like particles" has provided a consistent source of antigen (designated rNV). The purpose of the present study was to compare the antigenicities of these rNV particles with those of native NV antigen derived from human fecal material by using well-characterized sera obtained from earlier studies. In IEM studies, the rNV antigen reacted with NV-specific antibodies in a manner similar to that observed previously when particle-positive fecal material was used as antigen. In addition, a direct enzyme-linked immunosorbent assay, in which the rNV antigen was used as antigen, proved efficient and specific for the detection of serologic responses to NV compared with the previously established techniques of IEM and blocking antibody immunoassays in which particle-positive fecal material was used as the antigen. The availability of an unlimited source of antigen will enable serologic studies that will greatly increase our understanding of the epidemiology of NV and its role in human enteric illness.

Expression and Self-Assembly in Baculovirus of Porcine Enteric Calicivirus Capsids into Virus-Like Particles and Their Use in an Enzyme-Linked Immunosorbent Assay for Antibody Detection in Swine

“…This mechanism for expression of the viral capsid protein may be shared among caliciviruses. Because HuCV are uncultivable in cell culture and are genetically diverse, epidemiological investigations of human infections were impeded until recombinant calicivirus capsids which assembled into virus-like particles (VLPs) were produced and used to develop serologic diagnostic assays (12,19,22,23). The baculovirus expression system has proven very efficient for the production of recombinant capsids of NLVs such as Norwalk virus (NV), Mexico virus (MxV), Toronto virus, Hawaii virus, Grimsby virus, and also the rabbit hemorrhagic disease virus (RHDV), a lagovirus causing systemic hemorrhage and liver necrosis in rabbits (5,13,16,21,22,26,27).…”

Bovine noroviruses: A missing component of calf diarrhoea diagnosis

“…When expressed by baculovirus, capsid proteins of NoVs selfassemble into VLPs, which are morphologically and antigenically similar to infectious viral particles (Jiang et al, 1992;Green et al, 1993;Belliot et al, 2001;Han et al, 2005). VLPs are a source of antigens that can be used in serological assays (Jiang et al, 2000;Mauroy et al, 2009a;Di Martino et al, 2014b) and to produce polyclonal or monoclonal antibodies for antigen (Ag) ELISAs (Jiang et al, 2000;Han et al, 2005;Oliver et al, 2006).…”

Antiviral strategies to control calicivirus infections

“…In a recent study (Feng and Jiang, 2007), Feng et al screened a compound library using a saliva-based receptor binding assay for blocking the interaction of secreted HBGA and VLPs of the norovirus strain VA387. VLPs display similar antigenic properties to native virions and have been used as tools to investigate virus-host interactions and immune responses in animal models, and for screening potential anti-norovirus candidates (Green et al, 1993;Huang et al, 2003Huang et al, , 2005aJiang et al, 1992). In 14 of the 5000 compounds screened, an EC 50 value of less than 15 M was found, and in 2 compounds, an EC 50 < 5 M. Because HuCV are thought to replicate in intestinal cells, inhibition of attachment of HuCV to the HBGA receptor may represent an interesting strategy to inhibit infection of the cell.…”