Asexual blood stages of Plasmodium falciparum exhibit signs of secondary necrosis, but not classical apoptosis after exposure to febrile temperature (40 C)

It has been shown by others that after cultures of Plasmodium falciparum were exposed to a febrile temperature of 40 C, parasitemia was reduced in the subsequent generation, suggesting a temperature-induced inhibition of trophozoites and schizonts. In the current study, influences unique to cultivation were ruled out, demonstrating that 40 C impacted the parasites directly. Metabolic profiling of DNA synthesis, protein synthesis, and glucose utilization clearly indicated that febrile temperatures had a direct effect on parasite development, beginning 20-24 hr after erythrocyte invasion. The mechanism of parasite death was investigated for evidence of temperature-induced apoptosis. Lack of typical physiological hallmarks, namely, caspase activation, characteristic mitochondrial membrane potential changes, and DNA degradation as indicated by DNA laddering, eliminated 'classical' apoptosis as a mechanism of parasite death. Parasites dying under the influence of heat, staurosporine, and chloroquine initially appeared pyknotic by light and electron microscopy (as in apoptosis), but eventual swelling and lysis of the food vacuole membrane led to secondary necrosis. Chloroquine did induce DNA laddering, but it was later attributed to occult white blood cell contaminants. While not apoptosis, the results do not rule out other forms of temperature-induced programmed cell death.     

No evidence of fetal DNA persistence in maternal plasma after pregnancy

Short- and long-term persistence of fetal DNA in maternal plasma has been investigated. Short-term persistence at very low concentration was detected in 47 out of 105 women within two days after delivery. Twelve out of 13 samples re-tested within three days scored negative. No long-term persistence was detected in 172 women who had previous sons or abortions. Molecular microchimerism due to circulating fetal DNA persisting from previous pregnancies should not hamper non-invasive plasma-based prenatal testing.     

Persistent Antibody Clonotypes Dominate the Serum Response to Influenza over Multiple Years and Repeated Vaccinations

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Colonization history and population differentiation of the Honey Bees (Apis mellifera L.) in Puerto Rico

Honey bees (Apis mellifera L.) are the primary commercial pollinators across the world. The subspecies A. m. scutellata originated in Africa and was introduced to the Americas in 1956. For the last 60 years, it hybridized successfully with European subspecies, previous residents in the area. The result of this hybridization was called Africanized honey bee (AHB). AHB has spread since then, arriving to Puerto Rico (PR) in 1994. The honey bee population on the island acquired a mosaic of features from AHB or the European honey bee (EHB). AHB in Puerto Rico shows a major distinctive characteristic, docile behavior, and is called gentle Africanized honey bees (gAHB). We used 917 SNPs to examine the population structure, genetic differentiation, origin, and history of range expansion and colonization of gAHB in PR. We compared gAHB to populations that span the current distribution of A. mellifera worldwide. The gAHB population is shown to be a single population that differs genetically from the examined populations of AHB. Texas and PR groups are the closest genetically. Our results support the hypothesis that the Texas AHB population is the source of gAHB in Puerto Rico.     

A Randomized Trial of Pharmacogenetic Warfarin Dosing in Na?ve Patients with Non-Valvular Atrial Fibrillation

Genotype-guided warfarin dosing have been proposed to improve patient’s management. This study is aimed to determine whether a CYP2C9- VKORC1- CYP4F2-based pharmacogenetic algorithm is superior to a standard, clinically adopted, pharmacodynamic method. Two-hundred naïve patients with non-valvular atrial fibrillation were randomized to trial arms and 180 completed the study. No significant differences were found in the number of out-of-range INRs (INR<2.0 or >3.0) (p = 0.79) and in the mean percentage of time spent in the therapeutic range (TTR) after 19 days in the pharmacogenetic (51.9%) and in the control arm (53.2%, p = 0.71). The percentage of time spent at INR>4.0 was significantly lower in the pharmacogenetic (0.7%) than in the control arm (1.8%) (p = 0.02). Genotype-guided warfarin dosing is not superior in overall anticoagulation control when compared to accurate clinical standard of care.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01178034","term_id":"NCT01178034"}}NCT01178034     

Characteristics of Garden Dormice That Contribute to Their Capacity as Reservoirs for Lyme Disease Spirochetes

To describe the contribution of garden dormice to the epizootiology of Lyme disease, we compared their reservoir capacity for these pathogens to that of other sympatric hosts. Garden dormice are trapped most abundantly during early spring and again during midsummer, when their offspring forage. They are closely associated with moist forests. Garden dormice serve as hosts to nymphal ticks far more frequently than do other small mammals. Spirochetal infection is most prevalent in dormice, and many more larval ticks acquire infection in the course of feeding on these than on other rodents in the study site. Mature dormice appear to contribute more infections to the vector population than juveniles do. Replete larval ticks generally detach while their dormouse hosts remain within their nests. The population of garden dormice contributes five- to sevenfold more infections to the vector population than the mouse population does. Their competence, nymphal feeding density, and preference for a tick-permissive habitat combine to favor garden dormice over other putative reservoir hosts of Lyme disease spirochetes.     

Isolation of Three Novel Rat and Mouse Papillomaviruses and Their Genomic Characterization

Despite a growing knowledge about the biological diversity of papillomaviruses (PV), only little is known about non-human PV in general and about PV mice models in particular. We cloned and sequenced the complete genomes of two novel PV types from the Norway rat (Rattus norvegicus; RnPV2) and the wood mouse (Apodemus sylvaticus; AsPV1) as well as a novel variant of the recently described MmuPV1 (originally designated as MusPV) from a house mouse (Mus musculus; MmuPV1 variant). In addition, we conducted phylogenetic analyses using a systematically representative set of 79 PV types, including the novel sequences. As inferred from concatenated amino acid sequences of six proteins, MmuPV1 variant and AsPV1 nested within the Beta+Xi-PV super taxon as members of the Pi-PV. RnPV2 is a member of the Iota-PV that has a distant phylogenetic position from Pi-PV. The phylogenetic results support a complex scenario of PV diversification driven by different evolutionary forces including co-divergence with hosts and adaptive radiations to new environments. PV types particularly isolated from mice and rats are the basis for new animal models, which are valuable to study PV induced tumors and new treatment options.     

Elimination of Lyme Disease Spirochetes from Ticks Feeding on Domestic Ruminants

To determine whether and which spirochetes are cleared from Ixodes ricinus ticks during feeding on ruminants, ticks were removed from goats and cattle grazing on tick-infested pastures. Although about a quarter of ticks questing on the pasture were infected by spirochetes, no molted ticks that had previously engorged to repletion on ruminants harbored Lyme disease spirochetes. Borrelia miyamotoi spirochetes, however, appear not to be eliminated. Thus, the more subadult ticks are diverted from reservoir-competent hosts to zooprophylactic ruminants, the smaller the risk of infection by Lyme disease spirochetes is.Various vertebrates serve as reservoir hosts for the tick-borne agents of Lyme disease. A competent reservoir host acquires Lyme disease spirochetes when an infected tick feeds on it and maintains them to become and remain infectious for feeding ticks (10). It appears that each of the seven genospecies of Borrelia burgdorferi sensu lato prevalent in Central Europe is associated with particular reservoir hosts. Whereas rodents serve as a reservoir for B. afzelii and the recently differentiated but not yet validated “Borrelia bavariensis,” birds maintain B. garinii and B. valaisiana (3, 4). B. lusitaniae and B. spielmanii, on the other hand, seem to be limited to lizards and dormice, respectively (9, 12, 13). Ticks harboring rodent-associated spirochetes from their larval blood meal may lose the infectious burden when feeding as nymphs on a bird and vice versa (5). It appears that solely B. burgdorferi sensu stricto constitutes an intermediate position, since it may be perpetuated by birds and rodents (10, 11). As a generalist, B. burgdorferi sensu stricto appears to be less efficiently adapted to rodents than is the specialist B. afzelii. A host that is competent for one genospecies seems less competent or incompetent for another.The Central European vector tick, Ixodes ricinus, not only feeds on small animals. Wild ruminants, such as red, roe, and fallow deer, are frequently infested by all three stages of this tick (2, 6, 15). Interestingly, virtually no spirochetes were detected microscopically in ticks recovered from shot deer. On pastures, where domesticated ruminants graze at an extensive density, spirochetal infection in questing ticks is less prevalent than in nearby nonpastured sites (8). These ruminants appear to exert a zooprophylactic effect. Ruminants, although feeding numerous ticks, appear to be incompetent hosts for Lyme disease spirochetes. It is not known whether the incompetence of ruminants eliminates spirochetes in the feeding tick and whether it extends to each of the Lyme disease genospecies.To determine whether and which spirochetes are cleared from ticks feeding on ruminants, ticks were removed from goats and cattle grazing on tick-infested pastures and examined at various developmental stages for Lyme disease genospecies and B. miyamotoi. Infection rates in ruminant-derived ticks were compared to that in ticks questing on the pastures.The cattle study site was located southwest of the city of Flensburg, Germany, at the German-Danish border. The former training area of the German armed forces is used as low-intensity pasture, covering about 400 ha. Galloway cattle, in herds of mother cows, and Konik horses are allowed to graze year-round and are rotated on grazing patches. Most cattle which were examined for feeding ticks grazed in a 40-ha area which has been pastured since October 2004 and from which cattle and horses are excluded each year from April through June to permit rare plants to bloom and seed. The approximate grazing density of 0.25 livestock units (LU)/ha throughout the rest of the year fails to keep the vegetation short. The goat site was located about 50 km southeast of Stuttgart, Germany, near the village of Gruibingen in the Swabian highlands. Beech and juniper heath characterize the southern-facing mountain slopes, where goats were allowed to graze in a rotating regime during the vegetation period. The sites were in use as pastures for different lengths of time, with the oldest dating back to 2004.To obtain feeding ticks from cattle and goats, two approaches were used. For the yearly blood sampling in the spring, cattle were corralled into squeeze chutes. The head of each animal was examined for ticks. Feeding ticks were carefully removed with forceps, and replete ticks were gently rubbed off onto a sheet of fabric positioned under the cow''s head. From April through October 2006 and 2007 and in May of 2008, tame goats were examined individually for feeding ticks monthly and feeding ticks were removed with forceps. Ticks recovered from an individual animal were confined in screened vials and stored at 22°C to permit molting and/or until they were examined for spirochetes. Questing ticks were collected monthly from April through October 2008 in the cattle site and from April through October 2005 through 2007 at the goat site. They were collected by means of a flannel flag, identified to stage and species by microscopy, and preserved in 80% ethanol. To detect and identify the various spirochetes that may be present in questing or host-derived ticks, DNA from individual ticks was isolated, and a 600-nucleotide fragment of the gene carrying the 16S rRNA gene was amplified by nested PCR and sequenced as described previously (12). This method detects as little as a single spirochete even in the presence of tick and ruminant DNA. Each resulting sequence was compared with sequences of the same gene fragment representing various spirochetal genospecies. The following sequences were used for comparison: GenBank accession numbers {"type":"entrez-nucleotide","attrs":{"text":"X85196","term_id":"793782","term_text":"X85196"}}X85196 and {"type":"entrez-nucleotide","attrs":{"text":"X85203","term_id":"793783","term_text":"X85203"}}X85203 for B. burgdorferi sensu stricto, {"type":"entrez-nucleotide","attrs":{"text":"X85190","term_id":"793772","term_text":"X85190"}}X85190, {"type":"entrez-nucleotide","attrs":{"text":"X85192","term_id":"793777","term_text":"X85192"}}X85192, and {"type":"entrez-nucleotide","attrs":{"text":"X85194","term_id":"793778","term_text":"X85194"}}X85194 for B. afzelii, {"type":"entrez-nucleotide","attrs":{"text":"X85193","term_id":"793775","term_text":"X85193"}}X85193, {"type":"entrez-nucleotide","attrs":{"text":"X85199","term_id":"793785","term_text":"X85199"}}X85199, and {"type":"entrez-nucleotide","attrs":{"text":"M64311","term_id":"173944","term_text":"M64311"}}M64311 for B. garinii, {"type":"entrez-nucleotide","attrs":{"text":"X98228","term_id":"1769932","term_text":"X98228"}}X98228 and {"type":"entrez-nucleotide","attrs":{"text":"X98229","term_id":"1769933","term_text":"X98229"}}X98229 for B. lusitaniae, {"type":"entrez-nucleotide","attrs":{"text":"X98232","term_id":"1769937","term_text":"X98232"}}X98232 and {"type":"entrez-nucleotide","attrs":{"text":"X98233","term_id":"1769936","term_text":"X98233"}}X98233 for B. valaisiana, {"type":"entrez-nucleotide","attrs":{"text":"AY147008","term_id":"34391538","term_text":"AY147008"}}AY147008 for B. spielmanii, and {"type":"entrez-nucleotide","attrs":{"text":"AY253149","term_id":"34223988","term_text":"AY253149"}}AY253149 for B. miyamotoi. A complete match, permitting no more than two nucleotide changes, was required.Ticks removed while feeding on cattle or goats were examined for spirochetal DNA by nested PCR. Nineteen larvae were obtained during their feeding on goats, but none of the 17 engorged larvae and 2 resulting nymphs contained spirochetal DNA (Table ​(Table1).1). Of the 416 nymphal ticks that were obtained from 80 goats, only 9% developed to the adult stage, because most of the nymphs were only partially fed. None of the 37 resulting adults contained spirochetal DNA. However, three partially fed nymphal ticks were infected by Lyme disease spirochetes (0.8%), one each by B. afzelii, B. valaisiana, and B. lusitaniae. In three additional nymphs (0.8%), DNA of B. miyamotoi was detected. Of the 415 engorged nymphal ticks obtained from 42 cattle, as many as 319 (77%) molted to the adult stage, because mostly replete ticks had been collected from the cattle''s heads. None of the cattle-derived molted ticks harbored DNA of Lyme disease spirochetes. Four ticks, a nymph and three adults (one male and two females), contained DNA of B. miyamotoi. Of 306 partially engorged females removed from 68 goats, spirochetal DNA was detected in 9 females (2.9%); three harbored B. afzelii, four B. miyamotoi, and one each B. garinii and B. lusitaniae. In addition, 30 females which had fully engorged on cattle were tested for spirochetal DNA after egg-laying. None of these contained spirochetal DNA. Although DNA of Lyme disease spirochetes was detected in a rare partially fed tick, no molted tick that had previously engorged to repletion on a ruminant was infected by Lyme disease spirochetes. In contrast, B. miyamotoi appears to be present in ruminant-fed ticks regardless of their feeding state.

TABLE 1.

Borrelia genospecies detected in I. ricinus ticks that had engorged as larvae, nymphs, or adults on goats or cattle