Differential Protein Expression in the Hemolymph of Bithynia siamensis goniomphalos\textit{Bithynia siamensis goniomphalos} Infected with Opisthorchis viverrini\textit{Opisthorchis viverrini}

$\textit{Bithynia siamensis goniomphalos}$ is a freshwater snail that serves as the first intermediate host of the human liver fluke $\textit{Opisthorchis viverrini}$. This parasite is a major public health problem in different countries throughout the Greater Mekong sub-region (Thailand, southern Vietnam, Lao PDR and Cambodia). Chronic $\textit{O. viverrini}$ infection also results in a gradual increase of fibrotic tissues in the biliary tract that are associated with hepatobiliary diseases and contribute to cholangiocarcinoma (a fatal type of bile duct cancer). Infectivity of the parasite in the snail host is strongly correlated with destruction of helminths by the snail's innate immune system, composed of cellular (hemocyte) and humoral (plasma) defense factors. To better understand this important host-parasite interface we applied sequential window acquisition of all theoretical spectra mass spectrometry (SWATH-MS) to identify and quantify the proteins from the hemolymph of $\textit{B. siamensis goniomphalos}$ experimentally infected with $\textit{O. viverrini}$ and compare them to non-infected snails (control group). A total of 362 and 242 proteins were identified in the hemocytes and plasma, respectively. Of these, 145 and 117 proteins exhibited significant differences in expression upon fluke infection in hemocytes and plasma, respectively. Among the proteins with significantly different expression patterns, we found proteins related to immune response (up-regulated in both hemocyte and plasma of infected snails) and proteins belonging to the structural and motor group (mostly down-regulated in hemocytes but up-regulated in plasma of infected snails). The proteins identified and quantified in this work will provide important information for the understanding of the factors involved in snail defense against $\textit{O. viverrini}$ and might facilitate the development of new strategies to control $\textit{O. viverrini}$ infection in endemic areas.KS was supported by Development and Promotion of Science and Technology Talents Project (DPST) scholarship from the Institute for the Promotion of Teaching Science and Technology, Royal Thai Government, Thailand

Cluster analysis dendrogram.

<p>Cluster analysis dendrogram.</p

Seasonal and Spatial Environmental Influence on <i>Opisthorchis viverrini</i> Intermediate Hosts, Abundance, and Distribution: Insights on Transmission Dynamics and Sustainable Control

<div><p>Background</p><p><i>Opisthorchis viverrini</i> (<i>Ov</i>) is a complex-life-cycle trematode affecting 10 million people in SEA (Southeast Asia). Human infection occurs when infected cyprinid fish are consumed raw or undercooked. <i>Ov</i> requires three hosts and presents two free-living parasitic stages. As a consequence <i>Ov</i> transmission and infection in intermediate and human hosts are strongly mediated by environmental factors and understanding how environmental variability influences intermediate host abundance is critical. The objectives of this study were 1) to document water parameters, intermediate hosts abundance and infection spatio-temporal variation, 2) to assess their causal relationships and identify windows of transmission risk.</p><p>Methodology/Principal Findings</p><p>Fish and snails were collected monthly for one year at 12 sites in Lawa Lake, an <i>Ov-</i>endemic region of Khon Kaen Province in Northeast Thailand. Physicochemical water parameters [pH, temperature (Tp), dissolved oxygen (DO), Salinity, electrical conductivity (EC), total dissolved solid (TDS), nitrite nitrogen (NO₂-N), lead (Pb), total coliform bacteria (TCB) and fecal coliform bacteria (FCB)] were measured. Multivariate analyses, linear models and kriging were used to characterize water parameter variation and its influence on host abundance and infection prevalence. We found that sampling sites could be grouped in three clusters and discriminated along a nitrogen-salinity gradient where higher levels in the lake’s southern region predicted higher <i>Bithynia</i> relative abundance (<i>P</i><0.05) and lower snail and fish species diversity (<i>P</i><0.05). Highest <i>Bithynia</i> abundance occurred during rainy season (<i>P</i><0.001), independently of site influence. Cyprinids were the most abundant fish family and higher cyprinid relative abundance was found in areas with higher <i>Bithynia</i> relative abundance (<i>P</i><0.05). <i>Ov</i> infection in snails was anecdotal while <i>Ov</i> infection in fish was higher in the southern region (<i>P</i><0.001) at sites showing high FCB.</p><p>Conclusions/Significance</p><p>Our results indicate that water contamination and waterways configuration can influence freshwater communities’ assemblages possibly creating ideal conditions for sustained transmission. Sustainable control may require a better appreciation of the system’s ecology with wise governance and development planning particularly in the current context of SEA agricultural intensification and landscape modification.</p></div

Geospatial characteristics of the 12 sampling sites in Lawa Lake selected for the study.

<p>Geospatial characteristics of the 12 sampling sites in Lawa Lake selected for the study.</p

PCA environmental biplot.

<p>(A) PC1 –PC2 biplot, (B) PC5 –PC1 biplot, (C) PC2 –PC5 biplot. Sampling sites (dots) and variables (arrows). The green dots represent cluster 3 southern region sites; the black dots represent cluster 1 near shore sites; and the red dots represent cluster 2 deeper water sites.</p

A summary table illustrating the sampling site from each month reporting the highest infection rate for snails and fish.

<p>A summary table illustrating the sampling site from each month reporting the highest infection rate for snails and fish.</p

Descriptive summary of mean and range of water parameters collected from the 12 study sties in Lawa Lake from Feb.

<p>2013 –Jan. 2014. The highest mean values are marked by asterisks in descending order.</p

Map of the 12 sampling sites in Lawa Lake, which is approximately located in Ban Phai District of Khon Kaen Province, Northeast Thailand.

<p>Map of the 12 sampling sites in Lawa Lake, which is approximately located in Ban Phai District of Khon Kaen Province, Northeast Thailand.</p

Generalized linear mixed effects model assessing the influence of seasonality, site clusters and individual sampling sites on the relative abundance, species diversity and <i>Opisthorchis viverrini</i> infection rate in <i>Bsg</i> snails and cyprinid fish.

<p>Generalized linear mixed effects model assessing the influence of seasonality, site clusters and individual sampling sites on the relative abundance, species diversity and <i>Opisthorchis viverrini</i> infection rate in <i>Bsg</i> snails and cyprinid fish.</p