Novel components of the Apicomplexan moving junction reveal conserved and coccidia-restricted elements

Apicomplexan parasites generally invade their host cells by anchoring the parasite to the host membrane through a structure called the moving junction (MJ). This MJ is also believed to sieve host proteins from the nascent parasitophorous vacuole membrane, which likely protects the pathogen from lysosomal destruction. Previously identified constituents of the Toxoplasma MJ have orthologues in Plasmodium , indicating a conserved structure throughout the Apicomplexa. We report here two novel MJ proteins, RON5 and RON8. While RON5 is conserved in Plasmodium , RON8 appears restricted to the coccidia. RON8, which is likely essential, co-immunoprecipitates RON5 and known MJ proteins from extracellular parasites, indicating that a preformed complex exists within the parasites. Upon secretion, we show that RON8 within the MJ localizes to the cytoplasmic face of the host plasma membrane. To examine interactions between RON8 and the host cell, we expressed RON8 in mammalian cells and show that it targets to its site of action at the periphery in a manner dependent on the C-terminal portion of the protein. The discovery of RON5 and RON8 provides new insight into conserved and unique elements of the MJ, furthering our understanding of how the MJ contributes to the intricate mechanism of Apicomplexan invasion.     

Effect of maternal praziquantel treatment for Schistosoma japonicum infection on the offspring susceptibility and immunologic response to infection at age six,a cohort study

In areas endemic to schistosomiasis, fetal exposure to schistosome antigens prime the offspring before potential natural infection. Praziquantel (PZQ) treatment for Schistosoma japonicum infection in pregnant women has been demonstrated to be safe and effective. Our objectives were to evaluate whether maternal PZQ treatment modifies the process of in utero sensitization to schistosome antigens potentially impacting later risk of infection, as well as immune response to S. japonicum. We enrolled 295 children at age six, born to mothers with S. japonicum infection who participated in a randomized control trial of PZQ versus placebo given at 12–16 weeks gestation in Leyte, The Philippines. At enrollment, we assessed and treated current S. japonicum infection and measured serum cytokines. During a follow-up visit four weeks later, we assessed peripheral blood mononuclear cell (PBMC) cytokine production in response to soluble worm antigen preparation (SWAP) or soluble egg antigen (SEA). Associations between maternal treatment group and the child’s S. japonicum infection status and immunologic responses were determined using multivariate linear regression analysis. PZQ treatment during pregnancy did not impact the prevalence (P = 0.12) or intensity (P = 0.59) of natural S. japonicum infection among children at age six. Among children with infection at enrollment (12.5%) there were no significant serum cytokine concentration differences between maternal treatment groups. Among children with infection at enrollment, IL-1 production by PBMCs stimulated with SEA was higher (P = 0.03) in the maternal PZQ group compared to placebo. Among children without infection, PBMCs stimulated with SEA produced greater IL-12 (P = 0.03) and with SWAP produced less IL-4 (P = 0.01) in the maternal PZQ group compared to placebo. Several cytokines produced by PBMCs in response to SWAP and SEA were significantly higher in children with S. japonicum infection irrespective of maternal treatment: IL-4, IL-5, IL-10, and IL-13. We report that maternal PZQ treatment for S. japonicum shifted the PBMC immune response to a more inflammatory signature but had no impact on their offspring’s likelihood of infection or serum cytokines at age six, further supporting the safe use of PZQ in pregnant women.Trial Registration: ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00486863","term_id":"NCT00486863"}}NCT00486863.     

Detection of the threatened snail darter Percina tanasi in the Tennessee River system using environmental DNA

The distribution of many fishes that occupy large rivers is poorly known, in part due to the difficulties of sampling for them. This is especially true for small-bodied or rare species, such as the snail darter Percina tanasi, 44, 469–488; 1976). This federally listed (threatened) species has a limited distribution in the Tennessee River system in Alabama and Tennessee, where it is known from a few large tributaries or small rivers. In Alabama, P. tanasi was previously known from only one locality, but has recently been found in two additional, widely separated systems. These new records raise questions regarding the accuracy of our current understanding of the range for this species. Particularly, is P. tanasi present throughout the main stem Tennessee River, and is this species dispersing into new areas from source populations in the river? To clarify the distribution of P. tanasi in Alabama, 83 unique sites were surveyed using environmental DNA analysis. This cost-effective detection tool reduces the difficulty associated with empirically sampling large rivers for small fishes. Approximately 42% of sites sampled were positive for P. tanasi DNA. This study confirmed the known localities of P. tanasi in the Bear Creek, Elk River and Paint Rock River. Several new localities were also discovered throughout the main stem Tennessee River and in Shoal Creek, near Florence, Alabama. These findings can inform biologists about where to prioritize conservation efforts and further could lead to studies assessing movement and relatedness between populations in this system.