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Myxozoans are highly diverse and globally distributed cnidarian endoparasites in freshwater and marine habitats. They have adopted a heteroxenous life cycle, including invertebrate and fish hosts, and have been associated with diseases in aquaculture and wild fish stocks. Despite their importance, genomic resources of myxozoans have proven difficult to obtain due to their miniaturized and derived genome character and close associations with fish tissues. The first ‘omic’ datasets have now become the main resource for a better understanding of host–parasite interactions, virulence, and diversity, but also the evolutionary history of myxozoans.

Host organisms show altered phenotypic reactions when parasitised, some of which result from adaptive host manipulation, a phenomenon that has long been debated. Here, we provide an overview and discuss the rationale in distinguishing adaptive versus nonadaptive host behavioural manipulation. We discuss Poulin’s criteria of adaptive host behavioural manipulation within the context of Tinbergen’s four questions of ethology, while highlighting the importance of both the proximate and evolutionary explanations of such traits.

The path to a successful international career in science is daunting for most, and women in Africa are no exception. We are grossly under-represented as senior authors in high-impact publications and keynote speakers at international conferences, and rarely head major funding networks. Smashing long-held stereotypes may ease the journey.

Metabolic alterations occur in pathogen infections, but the role of lipid metabolism in the progression of bacterial mastitis is unclear. Crosstalk between lipid droplets (LDs) and invading bacteria occurs and targeting of de novo lipogenesis inhibits pathogen reproduction. Herein, we investigate the role(s) of lipid metabolism in mammary cells during Streptococcus uberis (S. uberis) infection. Our results indicate that S. uberis induces the synthesis of fatty acids and production of LDs. Importantly, taurine reduces fatty acid synthesis, the abundance of LDs and the in vitro bacterial load of S. uberis. These changes are mediated, at least partly, by the E3 ubiquitin ligase IDOL, which is associated with the degradation of low-density lipoprotein receptors (LDLRs). We have identified a critical role for IDOL-mediated fatty acid synthesis in bacterial infection, and suggest that taurine may be an effective prophylactic or therapeutic strategy for preventing S. uberis mastitis.

Enterococcus faecalis infections are considered a major public health concern worldwide. The complement system has a crucial role in the protection against different microbial pathogens including E. faecalis. Complement can be activated through three different pathways including; the classical, the lectin, and the alternative pathways. There is limited information on the role of the classical pathway (CP) in protection against infections caused by E. faecalis. In the present study, we generated Fab fragments that successfully block the CP in mouse via inhibition of a key enzyme C1s-A. Our results showed that anti C1s-A Fab fragments block CP mediated C3b and C4b deposition in vitro. We further showed that administration of anti C1s-A Fab fragments significantly impairs the CP functional activity in vitro and in vivo. Moreover, treatment of mice infected with E. faecalis using anti C1s-A Fab fragments significantly impairs bacterial clearance as determined from the viable bacterial counts recovered from blood, kidneys, spleens, livers, and lungs of infected mice. Overall, this study highlights the essential role of the CP in host defence against E. faecalis.

Haemaphysalis longicornis is a blood-feeding hard tick known for transmitting a variety of pathogens, including Babesia. How the parasites in the imbibed blood become anchored in the midgut of ticks is still unknown. Leucine-rich repeat domain (LRR)-containing protein, which is associated with the innate immune reaction and conserved in many species, has been detected in H. longicornis and has previously been indicated in inhibiting the growth of Babesia gibsoni. However, the detailed mechanism is unknown. In this study, one of the ligands for LRR from H. longicornis (HlLRR) was identified in B. microti, designated as BmActin (Babesia microti actin), using GST pull-down experiments and immunofluorescence assay. Moreover, RNA interference of HlLRR led to a decrease in the BmActin mRNA expression in the midgut of fully engorged ticks, which fed on B. microti-infected mice. We also found that the expression level of the innate immune molecules in H. longicornis, defensin, antimicrobial peptides (AMPs), and lysozyme were downregulated after the knockdown of HlLRR. However, subolesin expression was upregulated. These results indicate that HlLRR not only recognizes BmActin but may also modulate innate immunity in ticks to influence Babesia growth, which will further benefit the development of anti-Babesia vaccines or drugs.

Coronavirus disease 2019 (COVID-19) has dramatically altered our lives in 2020, a vivid reminder that infectious disease continues to threaten society....

Klebsiella pneumoniae is an opportunistic pathogen that mostly affects patients with weakened immune systems, but a few serotypes (especially K1 and K2) are highly invasive and result in systemic infection in healthy persons. The ability to evade and survive the components of innate immune system is critical in infection. To investigate the role and mechanism of transcription regulator KP1_RS12260 (KbvR) in the virulence and defence against innate immune response, the deletion mutant and complementary strains of kbvR were constructed. The in vivo animal infection assay and in vitro anti-phagocytosis assay demonstrate the K. pneumoniae KbvR is an important regulator that contributes to the virulence and the defence against phagocytosis of macrophage. The transcriptome analysis and phenotype experiments demonstrated the deletion of kbvR decreased production of capsular polysaccharide (CPS) and biosynthesis of partly outer membrane proteins. The findings suggest that KbvR is a global regulator that confers pathoadaptive phenotypes, which provide several implications for improving our understanding of the pathogenesis of K. pneumoniae.…

American Journal of Respiratory and Critical Care Medicine, Volume 203, Issue 4, Page 522-524, February 15, 2021.

E. Won et al.

C. V. Nonaka et al.

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