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Mucosal responses to parenteral and mucosal vaccines
1Department of Pediatrics, Children's Hospital, University of Texas Medical Branch, Galveston 77555-0351, USA.
Abstract:
Most human pathogens are acquired through mucosal portals of entry, and replicate in the mucosal tissues. Subsequently, the infecting agent may invade the blood stream and produce disease at distant systemic sites. However, a large number of pathogenic organisms are limited to development of disease only at the site of initial mucosal replication. Studies carried out with naturally acquired infections and mucosally delivered vaccines have provided strong evidence for the existence of a common mucosal immune system in the organized lymphoid follicles in respiratory and intestinal epithelium, and in the mucosa of genital tract, mammary glands, conjunctiva, upper airways, and the middle ear cavity. Mucosal application of live attenuated oral poliovaccine (OPV), rubella virus vaccine (RA 27/3), adenoviruses, influenza A virus, rotavirus, salmonella, and cholera vaccines have demonstrated consistent development of secretory IgA, serum antibody, and cellular immune responses. Mucosal immunization appears to result in preferential expression of several integrins and cell adhesion molecules associated with homing of lymphocytes to mucosal sites of immunization. Induction of mucosal immune responses often result in specific protection against reinfection challenge and against illness. Replicating agents introduced via the parenteral route also result in the development of mucosal responses and protection against systemic illness. Parenteral immunization with non-replicating agents often fails to induce specific mucosal responses. Such immunization, however, is quite effective in mounting high levels of serum antibody with development of protection against systemic illness. Parenteral vaccines, such as enhanced potency inactivated polio vaccine (eIPV), Haemophilus influenzae type B (HIB), hepatitis B virus (HBV), and other non-mucosal vaccines, have been highly effective in preventing systemic disease during subsequent exposure to natural infection. Recent evidence has shown that parenteral immunization can also be quite effective in inducing varying degrees of functional mucosal antibody responses as detected by ELISA and less frequently by neutralization. Systemic illnesses such as poliomyelitis and Haemophilus influenzae meningitis and community circulation of these agents has been eliminated or significantly limited in many parts of the world with the exclusive use of inactivated vaccines. Based on these observations, it is suggested that development of serum immunological responses are effective in the prevention of systemic disease regardless of the types of vaccines or route of their administration. However, induction of pathogen-specific antibody or cellular immunity at the mucosal sites is best elicited by mucosal application of the antigen.
Insights
Mucosal immunization effectively induces local immune responses and protection against infection. Parenteral vaccines primarily generate systemic immunity, preventing severe disease but with less mucosal protection.
Area of Science:
- Immunology
- Vaccinology
- Infectious Diseases
Background:
- Pathogens often enter and replicate at mucosal surfaces.
- A common mucosal immune system exists across various epithelial sites.
- Mucosal infections can lead to systemic disease or remain localized.
Purpose of the Study:
- To review the effectiveness of mucosal versus parenteral immunization strategies.
- To understand the induction of local and systemic immune responses by different vaccine routes.
- To evaluate the impact of immunization on mucosal immunity and disease prevention.
Main Methods:
- Review of studies on naturally acquired infections and vaccine-induced immune responses.
- Analysis of immune responses following mucosal and parenteral administration of various vaccines.
- Examination of cellular adhesion molecules and lymphocyte homing to mucosal tissues.
Main Results:
- Mucosal vaccines (e.g., oral poliovaccine) induce secretory IgA, serum antibodies, and cellular immunity, promoting mucosal protection.
- Parenteral vaccines (e.g., inactivated polio vaccine) primarily induce systemic immunity and prevent severe disease.
- Parenteral immunization can elicit some mucosal antibody responses, though less consistently than mucosal routes.
Conclusions:
- Serum immune responses are crucial for preventing systemic disease, irrespective of vaccine administration route.
- Inducing pathogen-specific immunity at mucosal sites is most effectively achieved through mucosal antigen delivery.
- Both parenteral and mucosal vaccination strategies play vital roles in controlling infectious diseases.