Therapeutic Potential of Marine Microbial Extracts against Veterinary RNA Viruses via Apoptosis-Mediated Antiviral Mechanisms = 인플루엔자 및 플라비바이러스 중심 수의학 RNA 바이러스 대응 항바이러스 활성과 치료 잠재력을 갖는 미생물 추출물 연구

다국어 초록 (Multilingual Abstract)

Veterinary and zoonotic RNA viruses—especially influenza viruses and flaviviruses—continue to exploit gaps in our antiviral toolbox, evolving rapidly across animal–human interfaces while antivirals for veterinary use remain scarce. This dissertation integrates in vitro virology with untargeted metabolomics to surface mechanism-anchored leads from marine microorganisms and to sketch a practical path toward translation. We combined (i) antiviral screening of marine bacterial and microalgal extracts, (ii) mechanistic phenotyping focused on cell death and replication stages, and (iii) LC–MS/MS chemoprofiling coupled to targeted testing of commercially available standards.
An extract from the coastal marine bacterium Parerythrobacter sp. M20A3S10 inhibited a panel of enveloped RNA viruses of veterinary importance—multiple influenza A subtypes (H1N1, H3N2), influenza B, Zika virus, and dengue virus serotype 2—most robustly when added after infection. This post-entry efficacy, together with flow-cytometric readouts, indicated a shift toward apoptosis-mediated control rather than early entry blockade, consistent with a host-directed component that sensitizes infected cells to caspase-dependent clearance. In parallel, extracts from the microalga Desmodesmus multivariabilis displayed broad activity against IAV, PEDV, and HAV. One strain (ME749) was notable for low cytotoxicity, marked suppression of cytopathic effects and viral RNA (≈3-log10), and a high selectivity index (≈23.8), highlighting microalgal metabolites as tractable, scalable candidates within a One Health frame.
To connect these biological signals to chemistry, we performed untargeted LC–MS/MS on a representative extract (Desmodesmus multivariabilis). The feature library was enriched for membrane-active and immunometabolic classes: lysophosphatidylcholines (LPC 16:4/18:4/18:3/18:2), monogalactosyl monoacylglycerols (MGMG 16:4/16:3), nitrogenous monoacylglyceride-like lipids (MGTS 16:0/18:4/18:3), oleylcarnitine, and phenolic/lignan signals (dimethylmatairesinol; tanacetol A–like), plus one N-rich unknown. These annotations suggest a complementary triad of mechanisms: (1) membrane-centric entry interference by curvature-active lyso-lipids that frustrate hemifusion and fusion-pore expansion; (2) virucidal envelope disruption favored by polyunsaturated acyl chains (e.g., 18:3); and (3) host-directed modulation of lipid metabolism and programmed cell death, signposted by acylcarnitines and phenolics.
Guided by this map, we assembled a panel of commercially available surrogates that match prominent LC–MS/MS features and evaluated them against influenza viruses and flaviviruses under virion pre-exposure (“pre-treat”) and post-infection (“post-treat”) conditions. LPC 18:3 and α-linolenic acid (18:3) emerged as the most consistent inhibitors in early-entry windows, while LPC 18:2 and stearidonic acid (18:4) formed a second tier. Dimethylmatairesinol showed modest, reproducible post-entry activity, and oleylcarnitine was largely inactive at non-cytotoxic concentrations. Together with the extract-level data, these results support a model in which lyso-lipids and PUFA-rich glycolipids provide high-barrier, protein-agnostic entry pressure, whereas phenolics modestly augment post-entry control, and host lipid pathways offer orthogonal leverage.
Limitations include the putative nature of several lipid annotations, isomeric complexity that clouds structure–activity rules, and the need for in vivo confirmation. Nonetheless, the convergence of extract efficacy, LC–MS/MS-guided hypotheses, and standard-based screens points to a coherent discovery path: pair time-of-addition, virion stability, and fusion assays with fatty-acid oxidation/acylcarnitine readouts; apply GNPS/FBMN-assisted dereplication and micro-fractionation; and prioritize synthesis/enrichment of 18:3-bearing LPC/glycolipids with formulation-minded delivery. By weaving together microbial biodiversity, membrane biophysics, and host immunometabolism, this work elevates marine bacterial and microalgal metabolites as mechanism-anchored, broad-spectrum antiviral leads against influenza viruses and flaviviruses—and charts a translational route suited to veterinary medicine and the One Health imperative.

목차 (Table of Contents)

• I. Therapeutic Efficacy of Marine Bacterium Parerythrobacter sp. M20A3S10 against Influenza and Flaviviruses 1
• 1. Introduction 1
• 2. Materials and Methods 5
• 3. Results 18
• 4. Discussion 37
• II. Evaluation of Desmodesmus multivariabilis Extracts Showing In Vitro Antiviral Effects on Veterinary RNA Viruses 43
• 1. Introduction 43
• 2. Materials and Methods 46
• 3. Results 52
• 4. Discussion 73
• III. LCMS/MS-Guided Profiling of Marine Microbial Extracts and Apoptosis-Linked Antiviral Insights 79
• 1. Introduction 79
• 2. Materials and Methods 83
• 3. Results 86
• 4. Discussion 96
• IV. General Discussion 101
• V. References 105
• VI. Abstract in Korean 117