Monoclonal Antibodies Targeting an Opisthorchis viverrini Extracellular Vesicle Tetraspanin Protect Hamsters against Challenge Infection

Opisthorchis viverrini causes severe pathology in the bile ducts of infected human hosts, and chronic infection can culminate in bile duct cancer. The prevention of infection by vaccination would decrease opisthorchiasis-induced morbidity and mortality. The tetraspanin protein, Ov-TSP-2, is located on the membrane of secreted extracellular vesicles (EVs), and is a candidate antigen for inclusion in a subunit vaccine. To address the role of anti-Ov-TSP-2 antibodies in protection, we assessed the protective capacity of anti-Ov-TSP-2 monoclonal antibodies (mAbs) against opisthorchiasis. Two anti-TSP-2 IgM mAbs, 1D6 and 3F5, and an isotype control were passively transferred to hamsters, followed by parasite challenge one day later. Hamsters that received 3F5 had 74.5% fewer adult flukes and 67.4% fewer eggs per gram of feces compared to hamsters that received the control IgM. Both 1D6 and 3F5 (but not the control IgM) blocked the uptake of fluke EVs by human bile duct epithelial cells in vitro. This is the first report of passive immunization against human liver fluke infection, and the findings portend the feasibility of antibody-directed therapies for liver fluke infection, bolstering the selection of TSPs as components of a subunit vaccine for opisthorchiasis and fluke infections generally.

The Overactivation of NADPH Oxidase during Clonorchis sinensis Infection and the Exposure to N-Nitroso Compounds Promote Periductal Fibrosis

Clonorchis sinensis, a high-risk pathogenic human liver fluke, provokes various hepatobiliary complications, including epithelial hyperplasia, inflammation, periductal fibrosis, and even cholangiocarcinogenesis via direct contact with worms and their excretory–secretory products (ESPs). These pathological changes are strongly associated with persistent increases in free radical accumulation, leading to oxidative stress-mediated lesions. The present study investigated C. sinensis infection- and/or carcinogen N-nitrosodimethylamine (NDMA)-associated fibrosis in cell culture and animal models. The treatment of human cholangiocytes (H69 cells) with ESPs or/and NDMA increased reactive oxidative species (ROS) generation via the activation of NADPH oxidase (NOX), resulting in augmented expression of fibrosis-related proteins. These increased expressions were markedly attenuated by preincubation with a NOX inhibitor (diphenyleneiodonium chloride) or an antioxidant (N-acetylcysteine), indicating the involvement of excessive NOX-dependent ROS formation in periductal fibrosis. The immunoreactive NOX subunits, p47phox and p67phox, were observed in the livers of mice infected with C. sinensis and both infection plus NDMA, concomitant with collagen deposition and immunoreactive fibronectin elevation. Staining intensities are proportional to lesion severity and infection duration or/and NDMA administration. Thus, excessive ROS formation via NOX overactivation is a detrimental factor for fibrogenesis during liver fluke infection and exposure to N-nitroso compounds.

Worm-free Cooking, Fish Safety: Recommendation to Strategy for Opisthorchiasis Prevention Program

Fish-borne parasitic zoonosis such as Opisthorchiasis caused by Opisthorchis viverrini remains a major public health problem in many parts of Southeast Asia and Me Kong Basin region including Thailand. The focal point of Opisthorchiasis is located in north-eastern part of Thailand, along with high prevalence coincidence of cholangiocarcinoma, a major primary carcinoma of the liver with a very poor prognosis. Opisthorchis viverrini infection caused by developed cholangiocarcinoma (CCA). O. viverrini infection is acquired by eating raw or partially cooked fish. In endemic areas, several food preparations contain uncooked or raw freshwater fish. The most common local freshwater fish used for this recipe are Koi Pla, Pla Som, Lab Pla and Pla Yang or Grill fish. Raw fish dishes are known to be associated with the risk of liver fluke infection due to the consumption of cyprinoid fish that contains metacercaria of O. viverrini. Grill fish and Lab-Pla are among the famous Thai traditional food in the northeastern and northern part of Thailand. The consumption of raw Grill fish can lead to O. viverrini infection because cyprinoid fish is a second intermediate host of O. viverrini. This study investigated the literature of previous working for prevention and control of Opisthorchiasis and confirm worm-free cooking safety of cooking with consideration of time for the preparation of freshwater fish-grill for the prevention and control of Opisthorchiasis and Cholangiocarcinoma infection. The unique experiment experimental designed. The freshwater fishes grill within the group of 0,1,2,3,4 and 5 minutes with 10 fresh water fishes from fisherman in Nakhon Phanom and Sakhon Nakorn provinces which reported high O. viverrini infection among risk people in 2009. The another experiment using frozen freshwater fish at -10 degree for 5 days. The results showed that metacercariae remained active in control and 1-2 minutes experimental groups. The groups 3-5 minutes of grill fish partially cooked showed inactive metacercariae. The excretory bladder spread with unclear form. The conclusion suggested that worm-free cooking under review, and unique experiment of cook safety is a crucial basic knowledge leading to bringing knowledge, practically for the prevention and control Liver fluke infection. Recommendation information also let people better understand the concerns during health literacy program to stop transmission of liver fluke and need to be discussed among head villagers, public health agencies and teachers in the public participation process and school health program.