Antibody-Dependent and -Independent Protection following Intranasal Immunization of Mice with Rotavirus Particles

Abstract

The ability to elicit protective immune responses after intranasal immunization with rotavirus particles, either with or without the attenuated Escherichia coli heat-labile enterotoxin LT(R192G) as an adjuvant, was examined in the adult mouse model. BALB/c mice were administered one or two inoculations of psoralen/UV-inactivated, triple-layered (tl) or double-layered (dl) purified rotavirus particles. Four weeks after immunization, mice were challenged with the murine rotavirus strain EDIM, and the shedding of rotavirus antigen was quantified. Rotaviruses used for immunization included EDIM and heterotypic simian (RRV), bovine (WC3), and human (89-12) strains. tl EDIM stimulated both systemic and intestinal rotavirus antibody responses and complete protection with as little as one 1-μg dose. Inclusion of LT(R192G) (10 μg) significantly increased rotavirus antibody responses and reduced antigen concentrations needed for full protection. Both dl EDIM and heterotypic dl and tl particles stimulated protection, but they did so less than tl EDIM at comparable concentrations, either with or without LT(R192G). When B-cell-deficient μMt mice were immunized with tl EDIM particles, protection was reduced to levels similar to those induced with dl EDIM and heterotypic particles in BALB/c mice. However, dl EDIM particles induced similar levels of protection in both mouse strains. The protection stimulated by tl or dl EDIM particles was not diminished by CD8 cell depletion prior to immunization in either strain of mice. These results indicate that tl EDIM induced immunity at least partially through responses to its outer capsid proteins, presumably by stimulation of serotype-specific neutralizing antibody. In contrast, the other particles stimulated protection primarily by an antibody-independent mechanism. Finally, depletion of CD8 cells had no effect on protection by either mechanism.

Intranasal immunization with inactivated SARS-CoV (SARS-associated coronavirus) induced local and serum antibodies in mice

“…Intranasal immunization with inactivated viruses has not succeeded in inducing effective antibodies in other studies, while several approaches to increase the efficacy of intranasal or other mucosal immunization by inactivated viruses, inactivated bacteria or constructs containing viral or bacterial proteins have been presented [13][14][15][16][17][18]. In this study we used CPG-ODN and CTB as adjuvants and PEG-precipitated inactivated virus was used to potentiate the uptake of the inactivated viruses by antigen presenting cells, and to maintain inactivated viruses at the site of administration.…”

Induction of mucosal immune responses and protection against enteric viruses: rotavirus infection of gnotobiotic pigs as a model

“…However, in a study of mice inoculated i.n. with puri®ed inactivated double-or triple-layered rotavirus particles, similar rates of protection were induced by the vaccines with or without adjuvant; although mLT signi®cantly increased antibody responses and reduced antigen concentrations needed for full protection (McNeal et al, 1999b). The discrepancies in rotavirus vaccine ef®cacies in studies of adult mice and neonatal pigs will be discussed further in a later section.…”

“…route has been shown to be more ef®cient for the induction of IgA antibody responses in the upper respiratory and genitourinary tract, and less ef®cient for the intestinal lamina propria in rodents and pigs (Brandtzaeg et al, 1999;McDermott and Bienenstock, 1979;VanCott et al, 1994), the i.n. vaccination route has been shown to be effective for induction of protective immunity against rotavirus infection in adult mice (O'Neal et al, 1997(O'Neal et al, , 1998McNeal et al, 1999b). In gnotobiotic pigs, double-layered 2/6-VLP vaccines derived from co-expression of the bovine RF core protein VP2 gene and the inner capsid protein VP6 gene of simian SA11 or human Wa rotavirus strains were evaluated using the i.n.…”

“…The outcome of vaccine ef®cacy studies using the adult mouse model of rotavirus infection also largely depends on the genetic background of the mouse strain (Franco and Greenberg, 2000). Uncharacterized innate immune mechanisms were suggested to play a major role in protective immunity against rotavirus infection in some mouse strains (Choi et al, 1999;Franco and Greenberg, 1999;McNeal et al, 1999b). The uncertainty of the roles of known immunologic effectors in protective immune responses to rotavirus in adult mice raises questions of the relevance of studies using adult mice as models for rotavirus immunity in neonatal farm animals and human infants.…”

Protective Immunity and Antibody-Secreting Cell Responses Elicited by Combined Oral Attenuated Wa Human Rotavirus and Intranasal Wa 2/6-VLPs with MutantEscherichia coliHeat-Labile Toxin in Gnotobiotic Pigs

“…The virulent Wa HRV (intestinal contents from infected gnotobiotic pigs) used for challenge contained 10 6 50% infectious doses (ID 50 ) (50,52,53). To prepare the double-layered inactivated Wa HRV inoculum, the attenuated Wa HRV was treated twice with 50 mM EDTA (25), purified by ultracentrifugation on CsCl gradients (9), and inactivated by using 0.01 M binary ethylenimine as previously described (2,15). The inactivated Wa HRV preparation was examined using immunoelectron microscopy to verify the size and morphologic integrity of the rotavirus particles (36).…”