Plasmodium vivax liver stage assay platforms using Indian clinical isolates

Abstract

Background Vivax malaria is associated with significant morbidity and economic loss, and constitutes the bulk of malaria cases in large parts of Asia and South America as well as recent case reports in Africa. The widespread prevalence of vivax is a challenge to global malaria elimination programmes. Vivax malaria control is particularly challenged by existence of dormant liver stage forms that are difficult to treat and are responsible for multiple relapses, growing drug resistance to the asexual blood stages and host-genetic factors that preclude use of specific drugs like primaquine capable of targeting Plasmodium vivax liver stages. Despite an obligatory liver-stage in the Plasmodium life cycle, both the difficulty in obtaining P. vivax sporozoites and the limited availability of robust host cell models permissive to P. vivax infection are responsible for the limited knowledge of hypnozoite formation biology and relapse mechanisms, as well as the limited capability to do drug screening. Although India accounts for about half of vivax malaria cases world-wide, very little is known about the vivax liver stage forms in the context of Indian clinical isolates. Methods To address this, methods were established to obtain infective P. vivax sporozoites from an endemic region in India and multiple assay platforms set up to detect and characterize vivax liver stage forms. Different hepatoma cell lines, including the widely used HCO4 cells, primary human hepatocytes as well as hepatocytes obtained from iPSC’s generated from vivax patients and healthy donors were tested for infectivity with P. vivax sporozoites. Results Both large and small forms of vivax liver stage are detected in these assays, although the infectivity obtained in these platforms are low. Conclusions This study provides a proof of concept for detecting liver stage P. vivax and provide the first characterization of P. vivax liver stage forms from an endemic region in India.

Optimization of Plasmodium vivax sporozoite production from Anopheles stephensi in South West India

“…In recent years, there has been increasing interest in the liver stages of P. vivax in India [ 16 , 17 ]. Research is underway at a field site in Goa to produce P. vivax sporozoites from clinical isolates [ 11 , 12 ].…”

“…In future, it will be important to find additional treatments and conditions to further improve the effectiveness of the sporozoites produced for liver infection. A recent report has shown low liver-infectivity of Indian P. vivax sporozoites in the currently available liver platforms [ 17 ]. Plasmodium vivax infection in the classical host HC-04 cells was also observed in the present study, but at a very low frequency.…”

Systems biology of malaria explored with nonhuman primates

“…Importantly, as the number of P. vivax clinical cases declines in endemic areas [ 1 ], the demand for NHP resources for investigating hypnozoites is expected to rise. Specifically, during the last decade, institutions in Thailand, Cambodia and India developed clinical capabilities and insectary operations to infect mosquitoes with human blood to attain sporozoites to infect hepatocyte culture systems [ 204 , 205 , 224 ]. These feats have been groundbreaking, but—if P. vivax clinical cases continue to decline, as hoped—logistical challenges will be compounded that include having sufficient availability of patient infected-blood donors, mosquito insectary operations, and experts for establishing, infecting, and analyzing the data coming from hepatocyte cultures.…”

Current Status and Challenges of Human Induced Pluripotent Stem Cell-Derived Liver Models in Drug Discovery

“…2D hPSC-HLC culture systems exploiting patient-derived iPSC, including genetically corrected isogenic cells, can also be used to model genetic liver diseases and identify new drug candidates for diseases, such as familial hypercholesterolemia, glycogen storage disease, Wilson's disease, Alpers syndrome, α1AT deficiency, Crigler-Najjar Type 1, defective mitochondrial respiratory chain complex disorder and hereditary tyrosinemia [41,42,44,45,[128][129][130][131][132][133][134]. In addition, 2D hPSC-HLC models also allow studying infectious liver diseases caused by Hepatitis B, C and E (reviewed in [135]) or malaria [136]. Finally, such 2D differentiation cultures could be upscaled and automated such that screening of toxicity or efficacy of drugs can be conducted at a medium throughput level (100-3000 compounds) and have been used for drug testing and liver toxicity screenings by different research groups, but are to the best of our knowledge not yet implemented in industrial testing platforms [71,128,[137][138][139].…”