Exploration of Immunology

Table 2. Comparative immune protection by LAVs and conventional vaccines.

Immune component	LAVs	Polysaccharide vaccines	Protein/Subunit vaccines	Reference(s)
Mucosal immunity	Secretory IgA induction via nasal colonization, for example, with a ΔhtrA strain, elicited potent mucosal antibodies and blocked recolonization. SPY1 induced mucosal IgA and protected against colonization.	Minimal mucosal response; poor induction of IgA at colonization sites.	Limited mucosal activation; mainly systemic antibody responses.	[77, 81, 82, 84]
Humoral immunity	Broad antibody repertoire against capsular and protein antigens. ΔhtrA induced systemic antibodies with cross-strain protection. SPY1 elicited systemic antibodies and cytokine responses (IFN-γ, IL-17A, IL-10, IL-4). Double-mutant strains broaden protein antigen coverage.	Capsule-specific antibodies; narrow protection, serotype-dependent.	Protein-specific antibodies: moderate breadth but limited durability.	[74, 77, 82, 85, 86, 93]
Cellular immunity (Th17/Th2)	Strong IL-17 response recruits neutrophils for mucosal clearance. Δlgt and ΔendA mutants modulate inflammatory signals. SPY1 induced Th17-mediated phagocyte recruitment and Th2 subsets for protection against lethal challenge.	Weak T-cell activation; poor cellular memory.	Variable T-cell activation; depends on adjuvant use.	[87, 88, 91]
Regulatory balance (Treg)	Balanced immune regulation; Treg cells prevent excessive inflammation while maintaining clearance.	Minimal Treg modulation; risk of poor regulation.	Partial regulation; adjuvant-dependent.	[87]
Microbiota interaction	Enhances long-term immunity via ecological interplay with commensals.	No microbiota engagement.	Limited microbiota effects.	[76]

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LAVs: live attenuated vaccines; Treg: T regulatory.

Declarations

Author contributions

MY: Conceptualization, Writing—original draft, Writing—review & editing. CCY: Validation, Writing—review & editing, Supervision. MA: Conceptualization, Investigation, Writing—review & editing, Validation, Supervision. All authors read and approved the submitted version.

Conflicts of interest

The authors declare that they have no conflicts of interest.

Ethical approval

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Consent to publication

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