Conformational changes in the glycoproteins of enveloped viruses are essential for membrane fusion, a critical step during both viral entry and the pathognomonic cell-cell fusion (syncytia) associated with many viral infections, such as those of the paramyxoviruses. However, technologies that detect glycoprotein conformational changes on actual enveloped virions are difficult and time-consuming for those viruses for which such detection is possible (1-6). Additionally, there is a great need for rapid identification and characterization of virions in medical, veterinary, or food samples. Having a method with these capabilities would advance the fields of virus diagnosis and analysis.Our model, Nipah virus (NiV), is an enveloped virus in the important Paramyxoviridae family, which comprises human and veterinary enveloped viruses such as measles virus, mumps virus, Newcastle disease virus, respiratory syncytial virus, canine distemper virus, the metapneumoviruses, the human parainfluenza viruses, Hendra virus (HeV), and NiV (6-8). NiV is an emerging zoonotic virus in the Henipavirus genus that causes severe illness in humans, characterized by encephalitis and respiratory disease associated with syncytium formation (7, 9). Although NiV causes 40 to 75% mortality in humans, there is no approved treatment; thus, NiV is classified as a biosafety level 4 agent and a priority pathogen in the NIH/NIAID agenda. Additionally, because paramyxoviruses are relatively stable in aerosols and NiV is capable of animal-to-animal, animal-to-human, and human-to-human transmission, NiV is considered a potential agro-and/or bioterrorism agent (7).Conformational changes of the viral glycoproteins are required for viral entry and cell-cell fusion. However, it is difficult to obtain X-ray crystal structural information from intact full-length glycoproteins because their hydrophobic transmembrane regions are embedded in a lipid membrane. Therefore, structural studies have been skewed toward ectodomain glycoprotein forms because it is relatively more straightforward to obtain structural information for them. Viral glycoprotein conformational changes have typically been observed either by analysis of viral glycoprotein soluble ectodomain forms (e.g., see references 10-12) or by analysis of full-length wild-type glycoproteins expressed on cell surfaces (e.g., see reference 13). Although soluble ectodomains normally bind their respective cell receptors, it is often not possible to assess how accurately their structures and structural changes compare with those of their membrane-bound full-length wild-type counterparts. Moreover, the tendency of soluble glycoprotein ectodomains to adopt postfusion conformations in many cases limits our ability to detect and characterize essential glycoprotein receptorinduced conformational changes (12,14). Analysis of receptorinduced conformational changes of full-length wild-type glycoproteins embedded in cellular or viral membranes is preferred, and even for such analyses, there may be differences in the role...

Plague is a flea-borne rodent-associated zoonotic disease caused by The disease is characterized by epizootics with high rodent mortalities, punctuated by interepizootic periods when the bacterium persists in an unknown reservoir. This study investigates the interaction between and the ubiquitous soil free-living amoeba (FLA) to assess if the bacterium can survive within soil amoebae and whether intracellular mechanisms are conserved between infection of mammalian macrophages and soil amoebae. The results demonstrate that during coculture with amoebae, representative strains of epidemic biovars Medievalis, Orientalis, and Antiqua are phagocytized and able to survive within amoebae for at least 5 days. Key determinants of the intracellular interaction of and phagocytic macrophages, PhoP and the type three secretion system (T3SS), were then tested for their roles in the -amoeba interaction. Consistent with a requirement for the PhoP transcriptional activator in the intracellular survival of in macrophages, a PhoP mutant is unable to survive when cocultured with amoebae. Additionally, induction of the T3SS blocks phagocytic uptake of by amoebae, similar to that which occurs during macrophage infection. Electron microscopy revealed that in, resides intact within spacious vacuoles which were characterized using lysosomal trackers as being separated from the lysosomal compartment. This evidence for prolonged survival and subversion of intracellular digestion of within FLA suggests that protozoa may serve as a protective soil reservoir for is a reemerging flea-borne zoonotic disease. Sylvatic plague cycles are characterized by an epizootic period during which the disease spreads rapidly, causing high rodent mortality, and an interepizootic period when the bacterium quiescently persists in an unknown reservoir. An understanding of the ecology of in the context of its persistence in the environment and its reactivation to initiate a new epizootic cycle is key to implementing novel surveillance strategies to more effectively predict and prevent new disease outbreaks. Here, we demonstrate prolonged survival and subversion of intracellular digestion of within a soil free-living amoeba. This suggests the potential role for protozoa as a protective soil reservoir for, which may help explain the recrudescence of plague epizootics.

The aim of this study was to measure the prevalence of gastrointestinal parasites (GI) in domestic animals and children in high mountain populations in the districts of Combia and Toche, Valle del Cauca–Colombia. These communities have been affected by the armed conflict in Colombia and are susceptible to health risk factors related to the Colombian post-conflict. Prevalence and risk factors were measured using Bayesian methods on 45 structured interviews applied to 29 families in Combia and 16 in Toche. This inquire aimed to analyze the socio-economic and demographic factors associated with the presence of parasites. This interview was conducted with 50 children: 40 (80%) from Rita Sabogal school district of Toche, and 10 (20%) from Tablones—Atanasio Girardot schools. 23 faecal samples from asymtomatic children from these schools were collected. Subsequently, 308 animals were characterized through the analysis of 64 faecal samples from asymptomatic individuals (20,8%); 18/41 from dogs (43,9%), 18/175 from poultry (10,3%), 7/13 from cats 56,84%, 6/20 from equines (30%) and from 15/59 cattle (25,43%). The prevalence of intestinal parasites among children under six years was 60% [95% PI = 41%-78%]; Endolimax nana , 24% [95% PI = 9,8%-42%]; Iodamoeba buetschlii , 16% [95% PI = 4,7%-32%]; Entamoeba coli , 35% [95% PI = 18%-55%]; Giardia lamblia , 12% [95% PI = 2,7%-27%]. In Equids the presence of Strongylus spp was 37% [95% PI = 10%-71%]; Parascaris equorum , 37% [95% PI = 10%-71%]; in dogs, Dipylidium caninum was 20% [95% PI = 6%-39%]; Trichuris trichiura , 9% [95% PI = 1,3%-26%]; Toxocara canis , 25% [95% PI = 9%-46%]; in cats, Toxocara cati had a prevalence of 44% [95% PI = 16%-75%]; cyst of Eimeria spp, 15% [95% PI = 3,4%-33%]; in poultry and Eimeria zuernii in cattle, 50% [95% PI = 23%-77%]. There was no association with exposure of humans to animal parasites. However, we conclude that female and children under 6 years of age are more likely OR (6,72–2,3) to get parasites.