Platform for Plasmodium vivax vaccine discovery and development

Plasmodium vivax is the most prevalent malaria parasite on the American continent. It generates a global burden of 80-100 million cases annually and represents a tremendous public health problem, particularly in the American and Asian continents. A malaria vaccine would be considered the most cost-effective measure against this vector-borne disease and it would contribute to a reduction in malaria cases and to eventual eradication. Although significant progress has been achieved in the search for Plasmodium falciparum antigens that could be used in a vaccine, limited progress has been made in the search for P. vivax components that might be eligible for vaccine development. This is primarily due to the lack of in vitro cultures to serve as an antigen source and to inadequate funding. While the most advanced P. falciparum vaccine candidate is currently being tested in Phase III trials in Africa, the most advanced P. vivax candidates have only advanced to Phase I trials. Herein, we describe the overall strategy and progress in P. vivax vaccine research, from antigen discovery to preclinical and clinical development and we discuss the regional potential of Latin America to develop a comprehensive platform for vaccine development

Single-Particle Fluorescence Intensity Fluctuations of Carbon Nanodots

Fluorescent carbon nanodots (CNDs) were synthesized in oxidized and reduced forms and were analyzed at the single-particle level. Images of single CNDs at different excitation energies revealed significant heterogeneity in the lower energy trap sites between particles. We observed that a high percentage of reduced CND particles transitioned between multiple fluorescence intensity levels indicative of multichromophoric systems. Despite this behavior, individual CNDs exhibit single-step photobleaching and transient blinking to the background level suggesting single-molecule behavior

Six Germline Genetic Variations Impair the Translesion Synthesis Activity of Human DNA Polymerase kappa

DNA polymerase (pol) κ efficiently catalyzes error-free translesion DNA synthesis (TLS) opposite bulky N2-guanyl lesions induced by carcinogens such as polycyclic aromatic hydrocarbons. We investigated the biochemical effects of nine human nonsynonymous germline POLK variations on the TLS properties of pol κ, utilizing recombinant pol κ (residues 1-526) enzymes and DNA templates containing an N2-CH2(9-anthracenyl)G (N2-AnthG), 8-oxo-7,8-dihydroguanine (8-oxoG), O6-methyl(Me)G, or an abasic site. In steady-state kinetic analyses, the R246X, R298H, T473A, and R512W variants displayed 7- to 18-fold decreases in kcat/Km for dCTP insertion opposite G and N2-AnthG, with 2- to 3-fold decreases in DNA binding affinity, compared to that of the wild-type, and further showed 5- to 190-fold decreases in kcat/Km for next-base extension from C paired with N2-AnthG. The A471V variant showed 2- to 4-fold decreases in kcat/Km for correct nucleotide insertion opposite and beyond G (or N2-AnthG) compared to that of the wild-type. These five hypoactive variants also showed similar patterns of attenuation of TLS activity opposite 8-oxoG, O6-MeG, and abasic lesions. By contrast, the T44M variant exhibited 7- to 11-fold decreases in kcat/Km for dCTP insertion opposite N2-AnthG and O6-MeG (as well as for dATP insertion opposite an abasic site) but not opposite both G and 8-oxoG, nor beyond N2-AnthG, compared to that of the wild-type. These results suggest that the R246X, R298H, T473A, R512W, and A471V variants cause a general catalytic impairment of pol κ opposite G and all four lesions, whereas the T44M variant induces opposite lesion-dependent catalytic impairment, i.e., only opposite O6-MeG, abasic, and bulky N2-G lesions but not opposite G and 8-oxoG, in pol κ, which might indicate that these hypoactive pol κ variants are genetic factors in modifying individual susceptibility to genotoxic carcinogens in certain subsets of populations. © 2016 American Chemical Society.