The genus Henipavirus (HNVs) includes two fatal viruses, namely Nipah virus (NiV) and Hendra virus (HeV). Since 1994, NiV and HeV have been endemic to the Asia–Pacific region and responsible for more than 600 cases of infections. Two emerging HNVs, Ghana virus (GhV) and Mojiang virus (MojV), are speculated to be associated with unrecognized human diseases in Africa and China, respectively. Despite many efforts to develop vaccines against henipaviral diseases, there is presently no licensed human vaccine. As HNVs are highly pathogenic and diverse, it is necessary to develop universal vaccines to prevent future outbreaks. The attachment enveloped glycoprotein (G protein) of HNVs mediates HNV attachment to the host cell’s surface receptors. G proteins have been used as a protective antigen in many vaccine candidates for HNVs. We performed quantitative studies on the antibody responses elicited by the G proteins of NiV, HeV, GhV, and MojV. We found that the G proteins of NiV and HeV elicited only a limited cross-reactive antibody response. Further, there was no cross-protection between MojV, GhV, and highly pathogenic HNVs. We then constructed a bivalent vaccine where the G proteins of NiV and HeV were fused with the human IgG1 Fc domain. The immunogenicity of the bivalent vaccine was compared with that of monovalent vaccines. Our results revealed that the Fc-based bivalent vaccine elicited a potent antibody response against both NiV and HeV. We also constructed a tetravalent Fc heterodimer fusion protein that contains the G protein domains of four HNVs. Immunization with the tetravalent vaccine elicited broad antibody responses against NiV, HeV, GhV, and MojV in mice, indicating compatibility among the four antigens in the Fc-fusion protein. These data suggest that our novel bivalent and tetravalent Fc-fusion proteins may be efficient candidates to prevent HNV infection.

Brucella spp. are Gram-negative, facultative intracellular pathogens that cause brucellosis in both humans and animals. The B. abortus vaccine strain 104 M is the only vaccine available in China for the prevention of brucellosis in humans. Although the B. abortus 104 M genome has been fully sequenced, the current genome annotations are not yet complete. In addition, the main mechanisms underpinning its residual toxicity and vaccine-induced immune protection have yet to be elucidated. Mapping the proteome of B. abortus 104 M will help to improve genome annotation quality, thereby facilitating a greater understanding of its biology. In this study, we utilized a proteogenomic approach that combined subcellular fractionation and peptide fractionation to perform a whole-proteome analysis and genome reannotation of B. abortus 104 M using high-resolution mass spectrometry. In total, 1,729 proteins (56.3% of 3,072) including 218 hypothetical proteins were identified using the culture conditions that were employed this study. The annotations of the B. abortus 104 M genome were also refined following identification and validation by reverse transcription-PCR. In addition, 14 pivotal virulence factors and 17 known protective antigens known to be involved in residual toxicity and immune protection were confirmed at the protein level following induction by the 104 M vaccine. Moreover, a further insight into the cell biology of multichromosomal bacteria was obtained following the elucidation of differences in protein expression levels between the small and large chromosomes. The work presented in this report used a proteogenomic approach to perform whole-proteome analysis and genome reannotation in B. abortus 104 M; this work helped to improve genome annotation quality. Our analysis of virulence factors, protective antigens and other protein effectors provided the basis for further research to elucidate the mechanisms of residual toxicity and immune protection induced by the 104 M vaccine. Finally, the potential link between replication dynamics, gene function, and protein expression levels in this multichromosomal bacterium was detailed.

Summary: Adenoviral vectors (AdV) are considered promising candidates for vaccine applications. A prominent group of Toll‐like receptors (TLRs) participate in the adenovirus‐induced adaptive immune response, yet there is little information regarding the role of TLR4 in AdV‐induced immune responses in recent literature. We investigated the function of TLR4 in both adaptive and innate immune responses to an AdV‐based anthrax vaccine. By immunizing wild‐type and TLR4 knockout (TLR4‐KO) mice, we revealed the requirement of TLR4 in AdV‐induced innate responses. We also showed that TLR4 functions are required for germinal centre responses in immunized mice, as expression of the apoptosis‐related marker Fas was down‐regulated on germinal centre B cells from TLR4‐KO mice. Likewise, decreased expression of inducible costimulator on follicular T helper cells was observed in immunized TLR4‐KO mice. Moreover, a potent protective antigen‐specific humoral immune response was mimicked using an adjuvant system containing the TLR4 agonist monophosphoryl lipid A. Overall, our findings showed that very rapid antigen‐specific antibody production is correlated with the TLR4‐imprinted germinal centre response to AdV‐based vaccine. These results provide additional evidence for the use of the AdV and a TLR agonist to induce humoral responses. Our findings offer new insights into rational vaccine design.

Lassa virus (LASV) is a rodent-borne arenavirus circulating in West African regions that causes Lassa fever (LF). LF is normally asymptomatic at the initial infection stage, but can progress to severe disease with multiorgan collapse and hemorrhagic fever. To date, the therapeutic choices are limited, and there is no approved vaccine for avoiding LASV infection. Adenoviral vector-based vaccines represent an effective countermeasure against LASV because of their safety and adequate immunogenicity, as demonstrated in use against other emerging viral infections. Here, we constructed and characterized a novel Ad5 (E1-, E3-) vectored vaccine containing the glycoprotein precursor (GPC) of LASV. Ad5-GPC_LASV elicited both humoral and cellular immune responses in BALB/c mice. Moreover, a bioluminescent imaging-based BALB/c mouse model infected with GPC-bearing and luciferase-expressing replication-incompetent LASV pseudovirus was utilized to evaluate the vaccine efficacy. The bioluminescence intensity of immunized mice was significantly lower than that of control mice after being inoculated with LASV pseudovirus. This study suggests that Ad5-GPC_LASV represents a potential vaccine candidate against LF.

The SARS-CoV-2 Omicron variant has become the dominant SARS-CoV-2 variant around the world and exhibits immune escape to current COVID-19 vaccines to some extent due to its numerous spike mutations. Here, we evaluated the immune responses to booster vaccination with intramuscular adenovirus-vectored vaccine (Ad5-nCoV), aerosolized Ad5-nCoV, a recombinant protein subunit vaccine (ZF2001) or homologous inactivated vaccine (CoronaVac) in those who received two doses of inactivated COVID-19 vaccines 6 months prior. We found that the Ad5-nCoV booster induced potent neutralizing activity against the wild-type virus and Omicron variant, while aerosolized Ad5-nCoV generated the greatest neutralizing antibody responses against the Omicron variant at day 28 after booster vaccination, at 14.1-fold that of CoronaVac, 5.6-fold that of ZF2001 and 2.0-fold that of intramuscular Ad5-nCoV. Similarly, the aerosolized Ad5-nCoV booster produced the greatest IFNγ T-cell response at day 14 after booster vaccination. The IFNγ T-cell response to aerosolized Ad5-nCoV was 12.8-fold for CoronaVac, 16.5-fold for ZF2001, and 5.0-fold for intramuscular Ad5-nCoV. Aerosolized Ad5-nCoV booster also produced the greatest spike-specific B cell response. Our findings suggest that inactivated vaccine recipients should consider adenovirus-vectored vaccine boosters in China and that aerosolized Ad5-nCoV may provide a more efficient alternative in response to the spread of the Omicron variant.