title: Immune responses elicited against rotavirus middle layer protein VP6 inhibit viral replication in vitro and in vivo.
abstract: Rotavirus (RV) is a common cause of severe gastroenteritis (GE) in children worldwide. Live oral RV vaccines protect against severe RVGE, but the immune correlates of protection are not yet clearly defined. Inner capsid VP6 protein is a highly conserved, abundant, and immunogenic RV protein, and VP6-specific mucosal antibodies, especially IgA, have been implicated to protect against viral challenge in mice. In the present study systemic and mucosal IgG and IgA responses were induced by immunizing BALB/c mice intranasally with a combination of recombinant RV VP6 protein (subgroup II [SGII]) and norovirus (NoV) virus-like particles (VLPs) used in a candidate vaccine. Following immunization mice were challenged orally with murine RV strain EDIMwt (SG non-I-non-II, G3P10[16]). In order to determine neutralizing activity of fecal samples, sera, and vaginal washes (VW) against human Wa RV (SGII, G1P1A[8]) and rhesus RV (SGI, G3P5B[3]), the RV antigen production was measured with an ELISA-based antigen reduction neutralization assay. Only VWs of immunized mice inhibited replication of both RVs, indicating heterotypic protection of induced antibodies. IgA antibody depletion and blocking experiments using recombinant VP6 confirmed that neutralization was mediated by anti-VP6 IgA antibodies. Most importantly, after the RV challenge significant reduction in viral shedding was observed in feces of immunized mice. These results suggest a significant role for mucosal RV VP6-specific IgA for the inhibition of RV replication in vitro and in vivo. In addition, these results underline the importance of non-serotype-specific immunity induced by the conserved subgroup-specific RV antigen VP6 in clearance of RV infection.
authors.affiliation: a Vaccine Research Center; School of Medicine; University of Tampere; Tampere, Finland.
authors.forename: Suvi
authors.initials: S
authors.lastname: Lappalainen
authors.forename: Ana Ruth
authors.initials: AR
authors.lastname: Pastor
authors.forename: Kirsi
authors.initials: K
authors.lastname: Tamminen
authors.forename: Vanessa
authors.initials: V
authors.lastname: López-Guerrero
authors.forename: Fernando
authors.initials: F
authors.lastname: Esquivel-Guadarrama
authors.forename: Laura A
authors.initials: LA
authors.lastname: Palomares
authors.forename: Timo
authors.initials: T
authors.lastname: Vesikari
authors.forename: Vesna
authors.initials: V
authors.lastname: Blazevic
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000032:analysis / Q000097:blood / Q000276:immunology*; D000914:Antibodies, Viral / Q000032:analysis / Q000097:blood / Q000276:immunology*; D000956:Antigens, Viral / Q000276:immunology*; D036022:Capsid Proteins / Q000276:immunology*; D005243:Feces / Q000737:chemistry; D005260:Female; D018928:Immunity, Mucosal; D007070:Immunoglobulin A / Q000032:analysis / Q000097:blood / Q000276:immunology*; D007074:Immunoglobulin G / Q000032:analysis / Q000097:blood / Q000276:immunology; D008807:Mice, Inbred BALB C; D012401:Rotavirus / Q000502:physiology*; D044967:Serum / Q000276:immunology; D014621:Vagina / Q000276:immunology; D014779:Virus Replication / Q000187:drug effects*; D017201:Virus Shedding
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000956:Antigens, Viral; D036022:Capsid Proteins; D007070:Immunoglobulin A; D007074:Immunoglobulin G; C061332:VP6 protein, Rotavirus
keywords: VP6; intranasal immunization; mucosal IgA; neutralization; rotavirus