Systematic evaluation of the induction of efficient neutralizing antibodies by recombinant multicomponent subunit vaccines against monkeypox virus.

Mpox (formerly known as monkeypox), which has symptoms similar to smallpox, is a zoonotic disease caused by the monkeypox virus (MPXV). From 1 January 2022 to 31 March 2024, 117 countries, territories, or areas reported 95,226 laboratory-confirmed cases of Mpox (including 185 deaths) to the World Health Organization. However, as there is no licensed specific MPXV vaccine available globally, the vaccines currently used for mpox prevention are mostly smallpox vaccines. Thus, the rapid development of safe and effective vaccines is urgently required. In the present study, the key MPXV proteins A35, B6R, E8L, A29, M1R, and H3L were expressed and prepared using a prokaryotic expression system (Escherichia coli) and a eukaryotic expression system (yeast), and the fusion antigens A35-A29 and A35-M1R were constructed based on the dimerization characteristics of the A35 protein. By combining the antigens with aluminum hydroxide and CpG adjuvants in different combinations, we developed nine multicomponent MPXV subunit vaccine candidates. Each antigen (10 µg) and fusion antigen (20 µg) were used to immunize the mice. The first two doses produced a mean titer of 10(Petersen et al., 2016 [5]), and the third dose maintained the same potent antibody-specific response as the previous two immunizations. The protective activity of different antigen combinations was determined using the cell neutralization test of vaccinia virus (VACV), which showed that the subunit vaccine candidates with two to six components (MPXV6/5/4/3a/3b/Fa/2a) had good neutralizing activity, and antigens A35 and M1R could produce neutralizing antibodies against VACV. The neutralizing antibody titer of the fusion antigen MPXVFa (A35-M1R), detected 2 weeks after the second booster dose, was comparable with that of MPXV2a (A35 and M1R). The A35-M1R fusion protein not only provided a high level of protection as a protective antigen but also simplified the preparation of candidate antigens. In summary, we systematically investigated the different protective antigen candidates of MPXV that have been widely studied and provided critical insights into the key protective antigen composition for vaccines, thus establishing a technical and theoretical foundation for the development of MPXV subunit vaccines.

Differential responses of abomasal transcriptome to Haemonchus contortus infection between Haemonchus-selected and Trichostrongylus-selected merino sheep.

Haemonchus contortus is the most prevalent and pathogenic gastrointestinal nematode infecting sheep and goats. The two CSIRO sheep resource flocks, the Haemonchus-selected flock (HSF) and Trichostrongylus-selected flock (TSF) were developed for research on host resistance or susceptibility to gastrointestinal nematode infection. A recent study focused on the gene expression differences between resistant and susceptible sheep within each flock, with lymphatic and gastrointestinal tissues. To identify features in the host transcriptome and understand the molecular differences underlying host resistance to H. contortus between flocks with different selective breeding and genetic backgrounds, we compared the abomasal transcriptomic responses of the resistant or susceptible animals between HSF and TSF flocks. A total of 11 and 903 differentially expressed genes were identified in the innate infection treatment in HSF and TSF flocks between resistant and susceptible sheep respectively, while 52 and 485 genes were identified to be differentially expressed in the acquired infection treatment, respectively. Among them, 294 genes had significantly different gene expression levels between HSF and TSF flock animals within the susceptible sheep by both the innate and acquired infections. Moreover, similar expression patterns of the 294 genes were observed, with 273 genes more highly expressed in HSF and 21 more highly expressed in the TSF within the abomasal transcriptome of the susceptible animals. Gene ontology enrichment of the differentially expressed genes identified in this study predicted the likely differing function between the two flock's susceptible lines in response to H. contortus infection. Nineteen pathways were significantly enriched in both the innate and adaptive immune responses in susceptible animals, which indicated that these pathways likely contribute to the host resistance development to H. contortus infection in susceptible sheep. Biological networks built for the set of genes differentially abundant in susceptible animals identified hub genes of PRKG1, PRKACB, PRKACA, and ITGB1 for the innate immune response, and CALM2, MYL1, COL1A1, ITGB1 and ITGB3 for the adaptive immune response, respectively. Our results offered a quantitative snapshot of host transcriptomic changes induced by H. contortus infection between flocks with different selective breeding and genetic backgrounds and provided novel insights into molecular mechanisms of host resistance.

From innate to adaptive immunity: Abomasal transcriptomic responses of merino sheep to Haemonchus contortus infection.

Although many important mediators and critical pathways are found to be involved in host immune responses to Haemonchus contortus infection, the initial responses to infection in the naïve and in the previously exposed state have not been compared at the transcriptional level. To further understand the development of adaptive immunity to H. contortus infection, we compared the early abomasal gene expression patterns between a primary and a tertiary challenge for four lines of sheep to discover differentially expressed genes (DEGs). The sheep were from the resistant (R) and susceptible (S) lines of two flocks of sheep selected for divergent responses to gastro-intestinal parasites (HSF and TSF). The flocks have separate origins and were initiated using two different strains of Merino sheep. One of the DEGs, mast cell proteinase 1, had significantly lower expression in tertiary compared to primary infections for all four lines of sheep. This gene was not identified in previous studies where resistant and susceptible sheep samples were compared within infection time points. Comparing the differentially expressed genes (DEGs) for the two R lines reveals that responses differed very little between the primary and tertiary challenges for HSFR and only two genes were identified, in contrast to the TSFR where there were 134 genes identified including the two identified using the HSFR animals. Similarly, comparing the primary and tertiary challenges for HSFS identified 15 DEGs, whilst for TSFS there were 128 DEGs identified. It is surprising that so few genes respond similarly between the two challenge regimes across the four lines of sheep, and suggests significant differences in immune mechanisms between the two flocks (across the lines) and also between the lines within flocks. Our results offer a quantitative snapshot comparing the transcriptome in the ovine abomasum between primary and tertiary infections with H. contortus in both genetically resistant and susceptible sheep.