title: Immunogenicity and protective efficacy of rotavirus 2/6-virus-like particles produced by a dual baculovirus expression vector and administered intramuscularly, intranasally, or orally to mice.
abstract: Virus-like particles (VLPs) are being evaluated as a candidate rotavirus vaccine. Rotavirus VLPs composed of simian SA11 strain VP2 and VP6 proteins (homologous 2/6-VLPs) were produced by cloning the rotavirus simian SA11 genes 2 and 6 into a single baculovirus transfer vector (pAcAB4). The overall yield of homologous 2/6-VLPs produced with the dual recombinant baculovirus was at least 30-fold higher than that of VLPs composed of bovine RF strain VP2 and simian SA11 strain VP6 (heterologous 2/6-VLPs), produced with single recombinant baculoviruses. Adult mice were immunized intramuscularly twice with various doses of homologous or heterologous 2/6-VLPs in QS-21, orally with or without cholera toxin (CT), or intranasally with mutant Escherichia coli heat-labile enterotoxin (LT-R192G). Both homologous and heterologous 2/6-VLPs were immunogenic and induced protection from challenge, with those administered parenterally or intranasally affording the highest mean protection from challenge. The 2/6-VLPs did not induce serum neutralizing antibody (N-Ab) responses, but these VLPs primed for a broad heterotypic N-Ab response, which was elicited after rotavirus challenge. Heterotypic N-Ab responses were not observed in 2/6-VLP vaccinated mice that were > or =94% protected from challenge. After challenge, control mice immunized with adjuvant alone developed only homotypic serum N-Ab responses. Similar results were obtained after challenge of rabbits immunized parenterally or intranasally with heterologous 2/6-VLPs. These results suggest that 2/6-VLPs prime the immune system to enhance the production of heterotypic N-Ab responses, but the induction of heterotypic N-Abs requires that virus replication occurs after challenge. The use of 2/6-VLPs expressed from a single recombinant baculovirus simplifies production and would reduce the cost of a VLP-based vaccine.
authors.affiliation: Department of Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza, BCM-385, Houston, TX 77030, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Bertolotti-Ciarlet
authors.forename: Max
authors.initials: M
authors.lastname: Ciarlet
authors.forename: Sue E
authors.initials: SE
authors.lastname: Crawford
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Conner
authors.forename: Mary K
authors.initials: MK
authors.lastname: Estes
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000281:Administration, Intranasal; D000284:Administration, Oral; D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis / Q000096:biosynthesis; D016367:Baculoviridae / Q000235:genetics*; D002772:Cholera Toxin / Q000494:pharmacology; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000821:virology; D005260:Female; D005822:Genetic Vectors / Q000235:genetics*; D007273:Injections, Intramuscular; D051379:Mice; D009500:Neutralization Tests; D011817:Rabbits; D012401:Rotavirus / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D012400:Rotavirus Infections / Q000517:prevention & control; D022243:Rotavirus Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D022243:Rotavirus Vaccines; D014613:Vaccines, Attenuated; D002772:Cholera Toxin