Key result
TLR4/7-adjuvanted liposomal FMDV vaccines boost early neutralizing antibodies and reduce acute inflammation versus liposomes alone.
Why the study?
Inactivated vaccines lack immunogenicity and require potent adjuvants, but the in vivo effects of adjuvants on innate immune responses and antibody production are not fully understood.
p-value: p=<0.05
Human blood transcriptional modules can be transferred to sheep to identify early vaccine-induced responses associated with antibody levels or unwanted inflammation.
Supports adjuvant optimization for early FMDV immunity in livestock models; leaves open translation to field use or other species.
Inactivated vaccines lack immunogenicity and therefore require potent adjuvants. To understand the in vivo effects of adjuvants, we used a system immunology-based analysis of ovine blood transcriptional modules (BTMs) to dissect innate immune responses relating to either antibody or haptoglobin levels. Using inactivated foot-and-mouth disease virus as an antigen, we compared non-adjuvanted to liposomal-formulated vaccines complemented or not with TLR4 and TLR7 ligands. Early after vaccination, BTM relating to myeloid cells, innate immune responses, dendritic cells, and antigen presentation correlated positively, whereas BTM relating to T and natural killer cells, as well as cell cycle correlated negatively with antibody responses. Interestingly, similar BTM also correlated with haptoglobin, but in a reversed manner, indicating that acute systemic inflammation is not beneficial for early antibody responses. Analysis of vaccine-dependent BTM modulation showed that liposomal formulations induced similar responses to those correlating to antibody levels. Surprisingly, the addition of the TLR ligands appeared to reduce early immunological perturbations and mediated anti-inflammatory effects, despite promoting antibody responses. When pre-vaccination BTM were analyzed, we found that high vaccine responders expressed higher levels of many BTM relating to cell cycle, antigen-presenting cells, and innate responses as compared with low responders. In conclusion, we have transferred human BTM to sheep and identified early vaccine-induced responses associated with antibody levels or unwanted inflammation in a heterogeneous and small group of animals. Such readouts are applicable to other veterinary species and very useful to identify efficient vaccine adjuvants, their mechanism of action, and factors related to low responders.
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Braun et al. (2018) studied Foot-and-mouth disease vaccination (n=18). Liposomal FMDV vaccine with TLR4 and TLR7 ligands vs. Antigen in PBS or liposomes alone was evaluated on Serum neutralizing antibody titers (p=<0.05). Liposomal FMDV vaccines adjuvanted with TLR4 and TLR7 ligands significantly enhanced early neutralizing antibody responses while reducing acute systemic inflammation compared to liposomes alone.
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