RESUMO
The G1P1A[8] rotavirus vaccine candidate 89-12, the precursor to Rotarix, stimulated high titers of neutralizing antibodies to non-G1/P1A[8] serotypes of human rotavirus in naturally infected subjects before attenuation by cell-culture passages. These responses were greatly diminished in young infants (median age, 11 weeks) administered the attenuated vaccine. Because of the possibility of improved responses in older infants, the immunogenicity of the 89-12 vaccine candidate was evaluated after administration of 2 doses beginning at either 4 or 6 months of age. As was found in young infants, neutralizing antibody responses to non-G1/P1A[8] rotaviruses were considerably lower than those observed after natural infection. The reasons identified were overall (P<.0001) lower neutralizing antibody responses stimulated by the attenuated 89-12 strain, compared with those stimulated by its virulent precursor, and 5 mutations selected in the gene encoding the immunodominant VP4 (P) neutralization protein. Even so, the Rotarix vaccine developed from attenuated 89-12 was found to elicit excellent protection against non-G1 rotaviruses.
Assuntos
Anticorpos Antivirais/imunologia , Infecções por Rotavirus/imunologia , Vacinas contra Rotavirus/imunologia , Rotavirus/imunologia , Vacinação , Administração Oral , Anticorpos Antivirais/sangue , Antígenos Virais/genética , Proteínas do Capsídeo/genética , Humanos , Esquemas de Imunização , Lactente , Mutação , Testes de Neutralização , Vacinas contra Rotavirus/administração & dosagem , Vacinas contra Rotavirus/genética , Inoculações Seriadas , Estados UnidosRESUMO
A quadrivalent precursor to the pentavalent rotavirus vaccine candidate RotaTeq was evaluated in a 3-dose, 439-subject study. To determine immunogenicity, the quantity of rotavirus immunoglobulin A (IgA) in stool specimens obtained, at 1 of 10 study sites, from 37 placebo and 37 vaccine recipients was measured. None of the placebo recipients showed a clinically important (>/=3-fold) increase in stool rotavirus IgA, whereas 31 vaccine recipients showed an increase after at least 1 dose of vaccine. In total, 16, 19, and 15 vaccine recipients had increases after 1, 2, and 3 doses, respectively, indicating that a 3-dose regimen increased the immune response elicited by this vaccine.