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

Parasite surveys and environmental management for prevention of parasitic infection in cultivated Barbonymus gonionotus (Cyprinidae) in fishponds, in an opisthorchiasis endemic area of northeast Thailand

Snails and fishes from ponds in an area endemic for human liver fluke (Opisthorchis viverrini) in Khon Kaen Province, northeast Thailand, were surveyed for the presence of zoonotic helminth parasites during May-November 2007. The surveys were performed to obtain information on the potential for transmission of these parasites to fish cultivated for human consumption. Sixteen species/subspecies of snails from 7 families and 14 species of fish from 6 families were collected for parasitological examination. Four species of snails were found to be infected with a range of trematode species. Bithynia siamensis goniomphalos, the first intermediate host of O. viverrini, was the most commonly infected with trematodes, with a prevalence of infection of 1.69-25.00% in 10 ponds. O. viverrini was found in 1 of 1065 (0.09%) B. siamensis goniomphalos individuals examined in one pond. Metacercariae of Echinostoma revolutum, another agent of human infection, was found in the snail Idiopoma umbilicata in one pond. The fish Luciosoma bleekeri was infected with the trematode Centrocestus caninus in one pond. An environmental management trial was conducted in selected ponds in the endemic area to measure the effects of exclusion of snails and thus trematode parasites. After modifications to the ponds and boundaries, including the exclusion of snails, the ponds were stocked with Barbonymus gonionotus fingerlings. Batches of the fingerlings from the same nursery farm were determined to be free of parasites prior to their introduction to the ponds. The experimental ponds were examined monthly for the presence of snails. Fish were also sampled monthly for parasites. After 8 months, fish grown in environmentally managed ponds were larger than those of the control pond. However, fish in all ponds were found to be infected with the trematode Haplorchis taichui. The source of this zoonotic species is uncertain and will require further investigation and potential environmental management, both at farms and at hatcheries. (C) 2014 Elsevier B.V. All rights reserved

Light and electron microscopy observations of embryogenesis and egg development in the human liver fluke, Opisthorchis viverrini (Platyhelminthes, Digenea)

Eggs of most species digenean flukes hatch in the external environment to liberate larvae that seek and penetrate a snail intermediate host. Those of the human liver flukes, Opisthorchis viverrini, hatch within the gastrointestinal canal of their snail hosts. While adult parasites are primarily responsible for the pathology in cases of human opisthorchiasis, their eggs also contribute by inducing granulomata and in serving as nidi for gallstone formation. In view of the peculiar biology of O. viverrini eggs and their contribution to pathology, we investigated embryogenesis in this species by light and transmission electron microscopy. Egg development was traced from earliest stages of coalescence in the ootype until full embryonation in the distal region of the uterus. Fully mature eggs were generally impermeable to resin and could not be examined by conventional electron microscopy methods. However, the use of high-pressure freezing and freeze-substitution fixation of previously fixed eggs enabled the internal structure of mature eggs, particularly the subshell envelopes, to be elucidated. Fertilization occurs in the ootype, and the large zygote is seen therein with a single spermatozoon wrapped around its plasma membrane. As the zygote begins to divide, the spent vitellocytes are pushed to the periphery of the eggs, where they progressively degrade. The early eggshell is formed in the ootype by coalescing eggshell precursor material released by approximately six vitelline cells. The early eggs have a thinner eggshell and are larger than, but lack the characteristic shape of, mature eggs. Characteristic shell ornamentation, the "muskmelon" appearance of eggs, appears after eggshell polymerization in the ootype. Pores are not present in the shell of O. viverrini eggs. The inner and outer envelopes are poorly formed in this species, with the outer envelope evident beneath the eggshell at the opercular pole of the mature egg. The miracidium has a conical anterior end that lacks the distinctive lamellar appearance of the terebratorium of other digeneans, such as the schistosomes. The miracidium is richly glandular, containing an apical gland in the anterior end, large cephalic gland, and posterior secretory glands. Each gland contains a secretory product with different structure. The paucity of vitelline cells associating with eggs, the reduced size of eggs, and reduced complexity of the extraembryonic envelopes are interpreted as adaptations to the peculiar hatching biology of the miracidia

Examining landscape determinants of Opisthorchis viverrini transmission

10.1007/s10393-012-0789-zEcoHealth93328-34