Different serogroups of Vibrio cholerae may inhabit the same ecological niche. However, serogroup O1/O139 strains are rarely isolated from their ecological sources. Quite plausibly, the non-O1/non-O139 vibrios and other bacterial species suppress growth of O1/O139 strains that share the same niche. Our bacterial inhibition assay data indicated that certain non-O1/non-O139 strains used a contact-dependent type VI secretion system (T6SS) to suppress growth of the O1 El Tor, N16961 pandemic strain. Comparative proteomics of the O1 and the suppressive non-O1/non-O139 strains co-cultured in a simulated natural aquatic microcosm showed that SecB and HlyD were upregulated in the latter. The HlyD-related effective factor was subsequently found to be hemolysin A (HlyA). However, not all hlyA-positive non-O1/non-O139 strains mediated growth suppression of the N16961 V. cholerae; only strains harboring intact cluster I HlyA could exert this activity. The key feature of the HlyA is located in the ricin-like lectin domain (β-trefoil) that plays an important role in target cell binding. In conclusion, the results of this study indicated that non-O1/non-O139 V. cholerae suppressed the growth of the O1 pandemic strain by using contact-dependent T6SS as well as by secreting the O1-detrimental hemolysin A during their co-persistence in the aquatic habitat.
Trichinella spiralis, a tissue-dwelling helminth, causes human trichinellosis through ingestion of undercooked meat containing the parasite’s infective larvae. However, benefits from T. spiralis infection have been documented: reduction of allergic diseases, inhibition of collagen-induced arthritis, delay of type 1 diabetes progression, and suppression of cancer cell proliferation. Since conventional cancer treatments have limited and unreliable efficacies with adverse side effects, novel adjunctive therapeutic agents and strategies are needed to enhance the overall treatment outcomes. This study aimed to validate the antitumor activity of T. spiralis infective larval extract (LE) and extricate the parasite-derived antitumor peptide. Extracts of T. spiralis infective larvae harvested from striated muscles of infected mice were prepared and tested for antitumor activity against three types of carcinoma cells: hepatocellular carcinoma HepG2, ovarian cancer SK-OV-3, and lung adenocarcinoma A549. The results showed that LE exerted the greatest antitumor effect on HepG2 cells. Proteomic analysis of the LE revealed 270 proteins. They were classified as cellular components, proteins involved in metabolic processes, and proteins with diverse biological functions. STRING analysis showed that most LE proteins were interconnected and played pivotal roles in various metabolic processes. In silico analysis of anticancer peptides identified three candidates. Antitumor peptide 2 matched the hypothetical protein T01_4238 of T. spiralis and showed a dose-dependent anti-HepG2 effect, not by causing apoptosis or necrosis but by inducing ROS accumulation, leading to inhibition of cell proliferation. The data indicate the potential application of LE-derived antitumor peptide as a complementary agent for human hepatoma treatment.
IntroductionBalamuthia (B.) mandrillaris is a free-living amoeba that can cause rare yet fatal granulomatous amoebic encephalitis (GAE). However, efficacious treatment for GAE is currently unavailable, especially when genomic studies on B. mandrillaris are limited.MethodsIn this study, B. mandrillaris strain KM-20 was isolated from the brain tissue of a GAE patient, and its mitochondrial genome was de novo assembled using high-coverage Nanopore long reads and Illumina short reads.Results and DiscussionPhylogenetic and comparative analyses revealed a range of diversification in the mitochondrial genome of KM-20 and nine other B. mandrillaris strains. According to the mitochondrial genome alignment, one of the most variable regions was observed in the ribosomal protein S3 (rps3), which was caused by an array of novel protein tandem repeats. The repeating units in the rps3 protein tandem region present significant copy number variations (CNVs) among B. mandrillaris strains and suggest KM-20 as the most divergent strain for its highly variable sequence and highest copy number in rps3. Moreover, mitochondrial heteroplasmy was observed in strain V039, and two genotypes of rps3 are caused by the CNVs in the tandem repeats. Taken together, the copy number and sequence variations of the protein tandem repeats enable rps3 to be a perfect target for clinical genotyping assay for B. mandrillaris. The mitochondrial genome diversity of B. mandrillaris paves the way to investigate the phylogeny and diversification of pathogenic amoebae.
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