Hemocyte siRNA uptake is increased by 5' cholesterol-TEG addition in Biomphalaria glabrata, snail vector of schistosome

The immune function of thioester-containing proteins in typical invertebrate disease vectors

Disease vectors, such as arthropods, primarily rely on innate immunity to counteract pathogen invasions, typically through the recognition and binding of pathogen-associated molecular patterns (PAMPs) by the host's pattern recognition receptors (PRRs). As a conserved immune effector gene family from insects to mammals, the complement system may play an essential role in combating pathogenic microorganisms. In arthropods, the complement proteins are often referred to as thioester-containing proteins (TEPs) because thioester motifs are one of the essential functional domains of the first proteins characterized within the C3 and A2M family. TEPs mainly function as specialized PRRs in sensing and binding to pathogens or their components. This paper presents a comprehensive review of the common domain and functions of TEPs in major disease vectors, in particular the specific decision-making ones expressed by Arthropoda (medical arthropods) and Mollusca (Biomphalaria glabrata) after pathogen infections. The relationship between the structure and antibacterial/antiviral activities of TEPs would further our understandings on the mechanisms governing the initiation of innate immune responses in typical disease vectors.

Accelerating snail vector genomics

The three most important genera of snails for the transmission of schistosomes are Bulinus, Biomphalaria and Oncomelania. Each of these genera, found in two distantly related families, includes species that act as the intermediate host for one of the three most widespread schistosome species infecting humans, Schistosoma haematobium, S. mansoni and S. japonicum, respectively. An important step in the fight against schistosomiasis in Asia has been taken with the publication of the article "Chromosome-level genome assembly of Oncomelania hupensis: the intermediate snail host of Schistosoma japonicum", which means that genomes for all three major genera, including species across three continents, are now available in the public domain. This includes the first genomes of African snail vectors, namely Biomphalaria sudanica, Bi. pfeifferi and Bulinus truncatus, as well as high-quality chromosome level assemblies for South American Bi. glabrata. Most importantly, the wealth of new genomic and transcriptomic data is helping to establish the specific molecular mechanisms that underly compatibility between snails and their schistosomes, which although diverse and complex, may help to identify potential targets dictating host parasite interactions that can be utilised in future transmission control strategies. This new work on Oncomelania hupensis and indeed studies on other snail vectors, which provide deep insights into the genome, will stimulate research that may well lead to new and much needed control interventions.

Snail microbiota and snail-schistosome interactions: axenic and gnotobiotic technologies

The microbiota in the intermediate snail hosts of human schistosomes can significantly affect host biology. For decades, researchers have developed axenic snails to manipulate the symbiotic microbiota. This review summarizes the characteristics of symbiotic microbes in intermediate snail hosts and describes their interactions with snails, affecting snail growth, development, and parasite transmission ability. We focus on advances in axenic and gnotobiotic technologies for studying snail-microbe interactions and exploring the role of microbiota in snail susceptibility to Schistosoma infection. We discuss the challenges related to axenic and gnotobiotic snails, possible solutions to address these challenges, and future research directions to deepen our understanding of snail-microbiota interactions, with the aim to develop microbiota-based strategies for controlling snail populations and reducing their competence in transmitting parasites.

Immuno-molecular profile for Biomphalaria glabrata/Schistosoma mansoni interaction

The complex innate immune defense of Biomphalaria glabrata, the intermediate host of Schistosoma mansoni, governs the successful development of the intramolluscan stages of the parasite. The interaction between the snail and the parasite involves a complex immune molecular crosstalk between several parasite antigens and the snail immune recognition receptors, evoking different signals and effector molecules. This work seeks to discuss the immune-related molecules that influence compatibility in Biomphalaria glabrata/Schistosoma mansoni interaction and the differential expression of these molecules between resistant and susceptible snails. It also includes the current understanding of the immune molecular determinants that govern the compatibility in sympatric and allopatric interactions, and the expression of these molecules after immune priming and the secondary immune response. Herein, the differences in the immune-related molecules in the interaction of other Biomphalaria species with Schistosoma mansoni compared to the Biomphalaria glabrata model snail are highlighted. Understanding the diverse immune molecular determinants in the snail/schistosome interaction can lead to alternative control strategies for schistosomiasis.

Delivery of siRNAs against MERS-CoV in Vero and HEK-293 cells: A comparative evaluation of transfection reagents

Background

A new coronavirus was identified in Jeddah, Saudi Arabia in 2012 and designated as Middle East Respiratory Syndrome Coronavirus (MERS-CoV). To date, this virus has been reported in 27 countries. The virus transmission to humans has already been reported from camels. Currently, there is no vaccine or antiviral therapy available against this virus.

Methods

The siRNAs were in silico predicted, designed, and chemically synthesized by using the MERS-CoV-orf1ab region as a target. The antiviral activity was experimentally evaluated by delivering the siRNAs with Lipofectamine™ 2000 and JetPRIME^R as transfection reagents in both Vero cell and HEK-293-T cell lines at two different concentrations (10.0 nM and 5.0 nM). The Ct value of quantitative Real-Time PCR (qRT-PCR) was used to calculate and determine the reduction of viral RNA level in both cell supernatant and cell lysate isolated from both cell lines.

Results

The sequence alignment resulted in the selection of highly conserved regions. The orf1ab region was used to predict and design the siRNAs and a total of twenty-one siRNAs were finally selected from four hundred and twenty-six siRNAs generated by online software. Inhibition of viral replication and significant reduction of viral RNA was observed against selected siRNAs in both cell lines at both concentrations. Based on the Ct value, the siRNAs # 11, 12, 18, and 20 were observed to be the best performing in both cell lines at both concentrations.

Conclusion

Based on the results and data analysis, it is concluded that the use of two different transfection reagents was significantly effective. But the Lipofectamine™ 2000 was found to be a better transfection reagent than the JetPRIME^R for the delivery of siRNAs in both cell lines.

Computational Design and Experimental Evaluation of MERS-CoV siRNAs in Selected Cell Lines

Middle East respiratory syndrome coronavirus (MERS-CoV) is caused by a well-known coronavirus first identified in a hospitalized patient in the Kingdom of Saudi Arabia. MERS-CoV is a serious pathogen affecting both human and camel health globally, with camels being known carriers of viruses that spread to humans. In this work, MERS-CoV genomic sequences were retrieved and analyzed by multiple sequence alignment to design and predict siRNAs with online software. The siRNAs were designed from the orf1ab region of the virus genome because of its high sequence conservation and vital role in virus replication. The designed siRNAs were used for experimental evaluation in selected cell lines: Vero cells, HEK-293-T, and Huh-7. Virus inhibition was assessed according to the cycle threshold value during a quantitative real-time polymerase chain reaction. Out of 462 potential siRNAs, we filtered out 21 based on specific selection criteria without off-target effect. The selected siRNAs did not show any cellular toxicity in the tested cell lines at various concentrations. Based on our results, it was obvious that the combined use of siRNAs exhibited a reduction in MERS-CoV replication in the Vero, HEK-293-T, and Huh-7 cell lines, with the highest efficacy displayed in the Vero cells.

Single-cell RNA-seq profiling of individual Biomphalaria glabrata immune cells with a focus on immunologically relevant transcripts

The immune cells of the snail Biomphalaria glabrata are classified into hyalinocyte and granulocyte subtypes. Both subtypes are essential for the proper functioning of the snail immune response, which we understand best within the context of how it responds to challenge with the human parasite Schistosoma mansoni. Granulocytes are adherent phagocytic cells that possess conspicuous granules within the cell cytoplasm. Hyalinocytes, on the other hand, are predominantly non-adherent and are known to produce a handful of anti-S. mansoni immune effectors. While our understanding of these cells has progressed, an in-depth comparison of the functional capabilities of each type of immune cell has yet to be undertaken. Here, we present the results of a single-cell RNA-seq study in which single granulocytes and hyalinocytes from S. mansoni-susceptible M-line B. glabrata and S. mansoni-resistant BS-90 B. glabrata are compared without immune stimulation. This transcriptomic analysis supports a role for the hyalinocytes as producers of immune effectors such as biomphalysin and thioester-containing proteins. It suggests that granulocytes are primarily responsible for producing fibrinogen-related proteins and are armed with various pattern-recognition receptors such as toll-like receptors with a confirmed role in the anti-S. mansoni immune response. This analysis also confirms that the granulocytes and hyalinocytes of BS-90 snails are generally more immunologically prepared than their M-line counterparts. As the first single-cell analysis of the transcriptional profiles of B. glabrata immune cells, this study provides crucial context for understanding the B. glabrata immune response. It sets the stage for future investigations into how each immune cell subtype differs in its response to various immunological threats.