Immune responses in Balb/c mice induced by a candidate SARS-CoV inactivated vaccine prepared from F69 strain

Abstract

The immunogenicity of a candidate-inactivated vaccine prepared from SARS-CoV F69 strain was evaluated in Balb/c mice. Potent humoral immune responses were induced under the elicitation of three times of immunizations at 2-week intervals with this vaccine, combined with three types of adjuvants (Freund's adjuvant, Al(OH)(3) adjuvant and CpG adjuvant). Titers of specific IgG antibodies in three test groups all peaked in the sixth week after first vaccination, but significant differences existed in the kinetics of specific IgG antibody levels. The strong neutralizing capacity exhibited in micro-cytopathic effect neutralization tests indicated the specific antibodies are protective. Western blot assay further demonstrated the specificity of the induced serum antibodies.

Prior Immunization with Severe Acute Respiratory Syndrome (SARS)-Associated Coronavirus (SARS-CoV) Nucleocapsid Protein Causes Severe Pneumonia in Mice Infected with SARS-CoV

“…The individual SARS-CoV structural protein-specific IgG titers are presented as the end point dilution Ab titers. The end point titer was defined as the reciprocal of the highest dilution of serum at which the absorbance at 490 nm (A 490 ) ratio (A 490 of m8rVV-NMES-immunized serum/A 490 of m8-immunized serum (negative control)) was greater than 2.0, as previously described (19).…”

Obstacles and advances in SARS vaccine development

“…Both T cell proliferation and cytokine upregulation was observed after boosting with the inactivated virus. Beta-propiolactone-inactivated virus also elicited neutralizing antibodies when administered to Balb/c mice [56] Formalin-inactivated SARS-CoV yielded potent humoral responses in Balb/c mice as well [57].…”

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“…Immunization with the non-adjuvanted vaccine resulted in complete protection of the upper respiratory tract and a significant (p<0.00001) reduction of viral titers in the lower respiratory tract of 30,000-fold compared to the control groups. A number of others tested whole virus vaccines using UV, BPL or formaldehyde to inactive the virus in mice and rabbits and combined them with different types of adjuvant [167][168][169][170]. Regardless of the method or combination used, all vaccines elicited strong immune responses underscoring the potential of this approach.…”