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Protein subunit vaccines of parainfluenza type 3 virus: immunogenic effect in lambs and mice
Abstract:
Protein subunit vaccines were prepared from a mixture of the haemagglutinin (HN) and fusion (F) glycoproteins of parainfluenza type 3 virus (PI-3). The glycoproteins were isolated in three different forms and characterized by their sedimentation coefficients: 30S protein micelles (a complex of several HN and F glycoproteins devoid of detergent and lipid), 18S protein-TX complexes (a complex of several glycoproteins containing the detergent Triton X-100), and 4S protein-TX complexes (probably monomers of the glycoproteins complexed to Triton X-100). These preparations were tested as vaccines in mice and lambs. The immune response in the mice was assayed both in the serum and in extracts from the lungs using an ELISA technique. Both of the multimeric complexes were highly immunogenic. The 30S protein micelles induced a high antibody response after two injections with either 10 or 1 microgram protein. The serum IgG titres reached levels of about 90 micrograms/ml and 40 micrograms/ml respectively. Similar titres were reached with the 18S protein-TX complexes. After two injections of either the 30S or the 18S complexes IgA antibody responses were detected in the lung extracts. The 4S protein-TX complexes were poor immunogens and induced low antibody responses in mice. The lambs were vaccinated with the 30S protein micelles, and the immune response was evaluated serologically and in challenge experiments. The 30S protein micelles in an oil adjuvant induced detectable serum antibody titres as well as protective immunity against the pneumonia caused by the PI-3 virus.
Insights
Multimeric protein subunit vaccines derived from parainfluenza type 3 virus (PI-3) glycoproteins elicited strong immune responses in mice and lambs. The 30S protein micelles demonstrated significant immunogenicity and protective immunity against PI-3 pneumonia.
Area of Science:
- Virology
- Immunology
- Vaccine Development
Background:
- Parainfluenza type 3 virus (PI-3) poses a significant threat, necessitating effective vaccine strategies.
- Protein subunit vaccines offer a promising avenue for PI-3 prevention.
Purpose of the Study:
- To evaluate the immunogenicity and efficacy of different forms of PI-3 virus haemagglutinin (HN) and fusion (F) glycoprotein subunit vaccines.
- To compare the immune responses induced by various glycoprotein complex sizes in animal models.
Main Methods:
- Preparation and characterization of three distinct forms of PI-3 glycoproteins: 30S protein micelles, 18S protein-TX complexes, and 4S protein-TX complexes.
- Vaccination of mice and lambs with these preparations.
- Assay of immune responses in mice using ELISA for serum and lung extracts.
- Evaluation of immune response and protective immunity in lambs through serological analysis and challenge experiments.
Main Results:
- Both multimeric complexes (30S and 18S) were highly immunogenic in mice, inducing significant serum IgG and lung IgA antibody responses.
- The 30S protein micelles elicited robust antibody titers at low doses (1-10 micrograms).
- The 30S protein micelles, when formulated with an oil adjuvant, induced protective immunity against PI-3 pneumonia in lambs.
Conclusions:
- Multimeric forms of PI-3 HN and F glycoproteins are effective subunit vaccine candidates.
- The 30S protein micelle preparation demonstrates significant potential for developing a PI-3 vaccine conferring protective immunity.