Single-cell transcription analysis of Plasmodium vivax blood-stage parasites identifies stage- and species-specific profiles of expression.

Plasmodium vivax and P. falciparum, the parasites responsible for most human malaria worldwide, exhibit striking biological differences, which have important clinical consequences. Unfortunately, P. vivax, unlike P. falciparum, cannot be cultivated continuously in vitro, which limits our understanding of its biology and, consequently, our ability to effectively control vivax malaria. Here, we describe single-cell gene expression profiles of 9,215 P. vivax parasites from bloodstream infections of Aotus and Saimiri monkeys. Our results show that transcription of most P. vivax genes occurs during short periods of the intraerythrocytic cycle and that this pattern of gene expression is conserved in other Plasmodium species. However, we also identify a strikingly high proportion of species-specific transcripts in late schizonts, possibly associated with the specificity of erythrocyte invasion. Our findings provide new and robust markers of blood-stage parasites, including some that are specific to the elusive P. vivax male gametocytes, and will be useful for analyzing gene expression data from laboratory and field samples

498-P: Prevalence and Impact on Quality of Life of Diabetic Retinopathy in African Americans with End-Stage Kidney Disease on Hemodialysis

Background: The prevalence, severity, and quality of life (QoL) impact of diabetic retinopathy (DR) among African Americans (AA) with end-stage-kidney disease (ESKD) receiving dialysis are unknown. Methods: We conducted a prospective cross-sectional study in 93 AA adults with type 1 (n=9) and type 2 (n=84) diabetes with ESKD on hemodialysis. The diagnosis of DR was based on a review of medical records and/or having a positive photograph with a portable hand-held device (Optomed Aurora retinal camera) reviewed by both artificial intelligence software (AEYE Health’s retinal screening system) and a retinal specialist. Visual acuity was assessed with the Snellen Chart. Associations with QoL (ascertained using kidney disease QoL and depression questionnaires), physical disability (ascertained using visual impairment questionnaire), and social determinants of health (SDoH) including personal and household income, marital status, health insurance, education, food insecurity, or employment status assessed by standardized questionnaires. Results: The overall prevalence of DR was 75%, with 33% of patients having mild, 9.6% moderate and 57.4% severe DR. A total of 43% had normal visual acuity, 45% had moderate and 12% severe visual impairment. We found high burden of disease, multiple SDoH challenges, and low QoL among all patients, with most unemployed or disabled, living below poverty line, mainly receiving public health insurance, reporting poor general health, and substantial time spent dealing with kidney disease interfered with daily and family activities. However, the presence of DR had no significant impact on physical health and QoL compared to subjects without DR. Conclusion: DR is present in 75% of AA patients with diabetes and ESKD on hemodialysis. ESKD has a significant burden on general health and QoL; however, DR has a minor additional impact on the overall physical health and QoL in people with ESKD and diabetes. Disclosure Z.E.Zabala: None. B.Moazzami: None. M.Egeolu: None. R.L.Caleon: None. A.Y.G.Gerges: None. R.J.Galindo: Consultant; Novo Nordisk, Eli Lilly and Company, Sanofi, Pfizer Inc., Bayer Inc., WW (Weight Watchers), Research Support; Novo Nordisk, Eli Lilly and Company, Dexcom, Inc. R.G.Mccoy: Consultant; Emmi. L.Peng: None. G.Umpierrez: Research Support; Abbott, Dexcom, Inc., Baxter

Artemisinin resistance phenotypes and K13 inheritance in a Plasmodium falciparum cross and Aotus model

Concerns about malaria parasite resistance to treatment with artemisinin drugs (ARTs) have grown with findings of prolonged parasite clearance t1/2s (>5 h) and their association with mutations in Plasmodium falciparum Kelch-propeller protein K13. Here, we describe a P. falciparum laboratory cross of K13 C580Y mutant with C580 wild-type parasites to investigate ART response phenotypes in vitro and in vivo. After genotyping >400 isolated progeny, we evaluated 20 recombinants in vitro: IC50 measurements of dihydroartemisinin were at similar low nanomolar levels for C580Y- and C580-type progeny (mean ratio, 1.00; 95% CI, 0.62–1.61), whereas, in a ring-stage survival assay, the C580Y-type progeny had 19.6-fold (95% CI, 9.76–39.2) higher average counts. In splenectomized Aotus monkeys treated with three daily doses of i.v. artesunate, t1/2 calculations by three different methods yielded mean differences of 0.01 h (95% CI, −3.66 to 3.67), 0.80 h (95% CI, −0.92 to 2.53), and 2.07 h (95% CI, 0.77–3.36) between C580Y and C580 infections. Incidences of recrudescence were 57% in C580Y (4 of 7) versus 70% in C580 (7 of 10) infections (−13% difference; 95% CI, −58% to 35%). Allelic substitution of C580 in a C580Y-containing progeny clone (76H10) yielded a transformant (76H10C580Rev) that, in an infected monkey, recrudesced regularly 13 times over 500 d. Frequent recrudescences of ART-treated P. falciparum infections occur with or without K13 mutations and emphasize the need for improved partner drugs to effectively eliminate the parasites that persist through the ART component of combination therapy