Studies were undertaken in volunteers to determine whether living adenovirus type 21 (ADV-21) vaccine could be safely administered orally to susceptible young adults. In the first study, ten volunteers were fed 10(6.4) tissue culture infectious dose(50) (TCID(50)) of ADV-21 vaccine virus, and five received placebo tablets. Nine of ten infected volunteers shed ADV-21 in stools (mean duration, 10.1 days; range, 4 to 17 days). No pharyngeal excretion of ADV-21 was observed in any of these volunteers. Each of the nine developed type-specific neutralizing (N) antibodies to ADV-21. No evidence for person-to-person transmission of vaccine was observed. In a second study, volunteers were immunized with ADV-21 vaccines containing 10(6.8), 10(4.6), and 10(2.4) TCID(50). ADV-21 N antibody responses were detected in nine of eleven who received the highest dose, six of twelve who received the middle dose, and two of twelve who were fed the lowest dose. None of twelve susceptible volunteers receiving the placebo capsule developed ADV-21 N antibodies postimmunization. This study established that the human infectious dose(50) for these lots of ADV-21 vaccine was approximately 10(4.6) TCID(50) and that the dose response to ADV-21 vaccine was lower than those previously reported for live ADV-4 and ADV-7 enteric vaccines.

Adenoviridae↗

PubMed1972

Enteric immunization with live adenovirus type 21 vaccine. II. Systemic and local immune responses following immunization.

Studies of the immunologic responses following administration of a live, enteric-coated adenovirus (ADV) type 21 vaccine showed that nine of ten vaccinees and none of five controls developed neutralizing antibody. Antibody activity of serum and secretory immunoglobulins was assayed by using a (14)C-labeled ADV-21 antigen in a radioimmunodiffusion system. Increases in immunoglobulin M, A and G (IgM, IgA, IgG) activity were detected in sera from vaccinees but not in those from controls. IgA copro antibody activity was also shown in vaccinees but not in controls. Nasal secretions showed no detectable IgA antibody responses by this method. These studies show marked differences in serum and local IgA antibody activity in induced enteric ADV infection compared to previously reported responses after natural infection. The protective role of secretory IgA in adenovirus infections is obscure. However, absence of nasal IgA responses may indicate that protection against disease with enteric ADV vaccines depends primarily upon humoral antibody.

Adenoviridae↗

PubMed1972

Human immunoglobulin specificity after group B arbovirus infections.

Sera obtained during a dengue-2 epidemic from individuals with primary or secondary group B arbovirus infections contained cross-reactive antibody against several viruses in this group. Hemagglutination-inhibition antibody titers of the immunoglobulin M fractions from these sera revealed a rise in antibody specific for dengue-2. The acute and convalescent sera in over half of the secondary infection group also had low-level unchanging immunoglobulin M antibody titers to yellow fever which implicated yellow fever immunization as the primary infection.

Antibody Specificity↗