Mice develop effective but delayed protective immune responses when immunized as neonates either intranasally with nonliving VP6/LT(R192G) or orally with live rhesus rotavirus vaccine candidates.
Rotavirus vaccines are delivered early in life, when the immune system is immature. To determine the effects of immaturity on responses to candidate vaccines, neonatal (7 days old) and adult mice were immunized with single doses of either Escherichia coli-expressed rotavirus VP6 protein and the adjuvant LT(R192G) or live rhesus rotavirus (RRV), and protection against fecal rotavirus shedding following challenge with the murine rotavirus strain EDIM was determined. Neonatal mice immunized intranasally with VP6/LT(R192G) were unprotected at 10 days postimmunization (dpi) and had no detectable rotavirus B-cell (antibody) or CD4(+) CD8(+) T-cell (rotavirus-inducible, Th1 [gamma interferon and interleukin-2 {IL-2}]-, Th2 [IL-5 and IL-4]-, or ThIL-17 [IL-17]-producing spleen cells) responses. However, by 28 and 42 dpi, these mice were significantly (P >or= 0.003) protected and contained memory rotavirus-specific T cells but produced no rotavirus antibody. In contrast, adult mice were nearly fully protected by 10 dpi and contained both rotavirus immunoglobulin G and memory T cells. Neonates immunized orally with RRV were also less protected (P=0.01) than adult mice by 10 dpi and produced correspondingly less rotavirus antibody. Both groups contained few rotavirus-specific memory T cells. Protection levels by 28 dpi for neonates or adults were equal, as were rotavirus antibody levels. This report introduces a neonatal mouse model for active protection studies with rotavirus vaccines. It indicates that, with time, neonatal mice develop full protection after intranasal immunization with VP6/LT(R192G) or oral immunization with a live heterologous rotavirus and supports reports that protection depends on CD4(+) T cells or antibody, respectively.
VanCott
John L
JL
Division of Infectious Diseases and Biostatistics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
Prada
Anne E
AE
McNeal
Monica M
MM
Stone
Susan C
SC
Basu
Mitali
M
Huffer
Bert
B
Smiley
Kristi L
KL
Shao
Mingyuan
M
Bean
Judy A
JA
Clements
John D
JD
Choi
Anthony H-C
AH
Ward
Richard L
RL
D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000281:Administration, Intranasal; D000284:Administration, Oral; D000818:Animals; D000831:Animals, Newborn; D000956:Antigens, Viral / Q000008:administration & dosage / Q000276:immunology*; D001427:Bacterial Toxins / Q000008:administration & dosage / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D036022:Capsid Proteins / Q000008:administration & dosage / Q000276:immunology*; D002478:Cells, Cultured; D004768:Enterotoxins / Q000008:administration & dosage / Q000276:immunology*; D029968:Escherichia coli Proteins / Q000008:administration & dosage / Q000276:immunology*; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D051381:Rats; D012401:Rotavirus / Q000276:immunology*; D022243:Rotavirus Vaccines / Q000008:administration & dosage / Q000276:immunology*; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology*; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000276:immunology
D000276:Adjuvants, Immunologic; D000956:Antigens, Viral; D001427:Bacterial Toxins; D036022:Capsid Proteins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D022243:Rotavirus Vaccines; C061332:VP6 protein, Rotavirus; D014613:Vaccines, Attenuated; D015164:Vaccines, Inactivated; C052014:rhesus rotavirus vaccine; C027538:heat-labile enterotoxin, E coli