TABLE 1 

Preclinical vaccine studies with dmLTa

Vaccine type and target pathogenAntigen(s)Route(s)Model(s)Major findings with adjuvant inclusionReference(s)
Subunit vaccines
    Clostridium difficilePilA1, PilJ, PilWp.o.MouseNAO; low levels of antipilin antibodies and no protection from weight loss after oral challenge; no clear difference from other routes/adjuvant combinations91
    Clostridium difficile and Shigella speciesChimeric toxin A/toxin B; IpaB/IpaDi.d., i.m., i.p.MouseNAO; route and delivery comparison with microneedles: similar responses in dmLT-adjuvanted i.d. as alum-adjuvanted i.p. groups for antibody responses and response to C. difficile challenge; development of IgG and mucosal IgA after i.d. and i.m. vaccination with dmLT to Shigella61
    Clostridium tetaniTetanus toxoidp.o., i.n.MouseEnhanced serum and mucosal antibodies, Th17 responses1, 8
    ETECEptAi.d., p.o., s.l.MouseNAO; route evaluation with adjuvanted vaccination: p.o., s.l., or i.d. delivery enhanced mucosal IgG and IgA; however, bacterial burden post-oral challenge reduced only with p.o. and s.l.; antibody avidity reduced in i.d. groups92
    Nontypeable H. influenzae otitis mediaLB1, rsPilA, chimV4t.c.i.ChinchillaEnhanced skin DC migration to lymphoid organs, serum IgG and IgA, and clearance of bacteria from nasopharynges/middle ears when combined with any antigen vaccine (prophylactic or therapeutic)55
chimV4t.c.i.ChinchillaNAO; enhanced mucosal IgG, IgA, IFN-γ+, and IL-17 CD4 T cells; eradication of bacterial burden and biofilms in middle ears22
chimV4t.c.i.ChinchillaNAO; enhanced antigen draining to lymphoid organs dependent upon therapeutic t.c.i. patch placement; enhanced Th1, Th17, ASCs, and mucosal IgM and IgG; reduced % of ears with otitis media and bacterial colonization observed with dmLT alone or in combination with antigen11
    Polymicrobial otitis mediarsPilA, chimV4, IHCt.c.i.ChinchillaNAO; enhanced antigen-specific ASCs and serum IgG, IgM, and IgA antibodies; reduced incidence of polymicrobial (viral-bacterial) otitis media and disease time course93
    Helicobacter pyloriLysate antigens, HpaA, UreBp.o.MouseEnhanced serum IgG, mucosal IgA, and splenic and stomach Th1 and Th17 responses; reduced bacterial colonization in stomach after oral challenge (equivalent to cholera toxin)12
Lysate antigens, freeze-driedp.o., s.l.MouseIncreased activation of ex vivo DCs; enhanced Th1, Th17, and IL-17A+ IFN-γ+ CD4 T cells in DLN or stomach after s.l. but not p.o. (equivalent to cholera toxin)13
    Hepatitis B virusHBsAg (bioencapsulated in maize)p.o.MouseNonsignificant enhancement of serum IgG and IgA antibody responses54
    Vibrio choleraePolysaccharide conjugate (OSP-TThc)i.m.MouseEnhanced level and vibriocidal activity of serum antibodies, formation of memory B cells, and survival by neonatal mice of lethal challenge57
    Shigella speciesIpaB, IpaD, IpgC, IpaB/IpgCi.n.MouseNAO; antigen evaluation with adjuvanted i.n. vaccination: improvement of serum and mucosal IgG and IgA, ASCs, Th1 responses, and protection from i.n. challenge94
IpaB/IpaDi.d.MouseEnhanced level of serum antibodies, protection from lethal i.n. challenge (antigen dose dependent) with microneedle delivery9
IpaB/IpaDi.d., s.l.MouseNAO; route evaluation with adjuvanted vaccination: i.d. delivery enhanced mucosal IgG; s.l. delivery enhanced mucosal IgG and IgA; i.d. plus s.l. exhibited maximal mucosal IgG and IgA23
PSSP-1i.n., i.d.MouseNAO; enhanced protection to i.n. challenge with multiple Shigella species and serotypes after i.n. but not i.d. immunization60
Whole-killed vaccines
    ETECWhole-killed plus LCTBA (ETVAX)p.o.MouseEnhanced serum IgG and fecal IgA antibodies (equivalent or better than CT)59
    Helicobacter pyloriFormalin inactivated, liquid or freeze-driedp.o.MouseNo significant increase in serum IgG responses; however, after oral challenge, reduced stomach urease activity and stomach bacterial burden (equivalent to or better than mLT)38
    Shigella speciesFormalin inactivated trivalent (S. flexneri 2a and 3a and Shigella sonnei)i.n.Mouse, guinea pigIn mice, no major adjuvant effect except with low antigen dose (IgA and protection from lethal i.n. challenge); in guinea pig, same or worse response to ocular challenge58
    Streptococcus pneumoniaeChloroform-killed nonencapsulated strain RM200b.c., s.l.MouseReduced bacterial burden after i.n. challenge and increased IL-17 secretion (comparison with nonadjuvanted groups performed with only mLT and CT adjuvants)10
    PoliovirusFormalin inactivated trivalent (IPV)s.l.MouseEnhanced antigen dose-sparing, serum IgG, salivary IgA, and virus-neutralizing antibodies with thermoresponsive gel delivery system56
i.d., i.m.MouseEnhanced germinal center markers, antigen dose sparing, serum IgG, fecal IgA, and virus-neutralizing antibodies21
Live-attenuated vaccines
    Salmonella enteritidisStrain JOL1087 ± secreted dmLTi.m., p.o.ChickenBiological incorporation of dmLT into vaccine strain increased plasma IgG, intestinal sIgA, PBMC
stimulation, and splenic cytokines (IFN-γ, IL-6, and IL-10) and reduced bacterial colonization after oral challenge
62, 90
  • a Abbreviations: ASCs, antibody-secreting cells; DC, dendritic cell; DLN, draining lymph node; IHC, integration host factor; IPV, inactivated polio vaccine; NAO, no antigen-only group without dmLT.