A Study of Cross-Protection between Eimeria maxima Immunovariants

For reasons unknown, Eimeria maxima is unique among Eimeria species infecting chickens in the immunovariability it displays among isolates from different geographical areas. Eimeria maxima oocysts (named EmaxAPU3) were isolated late in grow-out (6 weeks) from litter in a commercial broiler operation that was using Eimeria vaccination as the coccidiosis control program. Cross-protection studies (n = 4) were conducted in immunologically naïve chickens between EmaxAPU3 and two E. maxima lab strains (EmaxAPU1, EmaxAPU2) by immunizing with one E. maxima strain and challenging with either the homologous or heterologous E. maxima. As measured by oocyst output, immunization with EmaxAPU1 protected against homologous challenge (EmaxAPU1) and against heterologous challenge with EmaxAPU3, but not against EmaxAPU2. Similarly, immunization with EmaxAPU3 protected against homologous challenge (EmaxAPU3) and against heterologous challenge with EmaxAPU1, but not against EmaxAPU2. Immunization of chickens with EmaxAPU2 elicited a protective response against homologous challenge (EmaxAPU2), but not against EmaxAPU1 nor EmaxAPU3. The most plausible explanation for the appearance of this immunovariant late in grow-out is that E. maxima APU3 escaped immunity directed to E. maxima antigenic types in the commercial vaccine.

Chromosomal scale assembly reveals localized structural variants in avian caecal coccidian parasite Eimeria tenella

Eimeria tenella is a major cause of caecal coccidiosis in commercial poultry chickens worldwide. Here, we report chromosomal scale assembly of Eimeria tenella strain APU2, a strain isolated from commercial broiler chickens in the U.S. We obtained 100× sequencing Oxford Nanopore Technology (ONT) and more than 800× Coverage of Illumina Next-Seq. We created the assembly using the hybrid approach implemented in MaSuRCA, achieving a contiguous 51.34 Mb chromosomal-scale scaffolding enabling identification of structural variations. The AUGUSTUS pipeline predicted 8060 genes, and BUSCO deemed the genomes 99% complete; 6278 (78%) genes were annotated with Pfam domains, and 1395 genes were assigned GO-terms. Comparing E. tenella strains (APU2, US isolate and Houghton, UK isolate) derived Houghton strain of E. tenella revealed 62,905 high stringency differences, of which 45,322 are single nucleotide polymorphisms (SNPs) (0.088%). The rate of transitions/transversions among the SNPs are 1.63 ts/tv. The strains possess conserved gene order but have profound sequence heterogeneity in a several chromosomal segments (chr 2, 11 and 15). Genic and intergenic variation in defined gene families was evaluated between the two strains to possibly identify sequences under selection. The average genic nucleotide diversity of 2.8 with average 2 kb gene length (0.145%) at genic level. We examined population structure using available E. tenella sequences in NCBI, revealing that the two E. tenella isolates from the U.S. (E. tenella APU2 and Wisconsin, "ERR296879") share a common maternal inheritance with the E. tenella Houghton. Our chromosomal level assembly promotes insight into Eimeria biology and evolution, hastening drug discovery and vaccine development.

RNA-Seq of Phenotypically Distinct Eimeria maxima Strains Reveals Coordinated and Contrasting Maturation and Shared Sporogonic Biomarkers with Eimeria acervulina

Strains of Eimeria maxima, an enteric parasite of poultry, vary in virulence. Here, we performed microscopy and RNA sequencing on oocysts of strains APU-1 (which exhibits more virulence) and APU-2. Although each underwent parallel development, APU-1 initially approached maturation more slowly. Each strain sporulated by hour 36; their gene expression diverged somewhat thereafter. Candidate biomarkers of viability included 58 genes contributing at least 1000 Transcripts Per Million throughout sporulation, such as cation-transporting ATPases and zinc finger domain-containing proteins. Many genes resemble constitutively expressed genes also important to Eimeria acervulina. Throughout sporulation, the expression of only a few genes differed between strains; these included cyclophilin A, EF-1α, and surface antigens (SAGs). Mature and immature oocysts uniquely differentially express certain genes, such as an X-Pro dipeptidyl-peptidase domain-containing protein in immature oocysts and a profilin in mature oocysts. The immature oocysts of each strain expressed more phosphoserine aminotransferase and the mature oocysts expressed more SAGs and microneme proteins. These data illuminate processes influencing sporulation in Eimeria and related genera, such as Cyclospora, and identify biological processes which may differentiate them. Drivers of development and senescence may provide tools to assess the viability of oocysts, which would greatly benefit the poultry industry and food safety applications.

Hastening Progress in Cyclospora Requires Studying Eimeria Surrogates

Cyclospora cayetanensis is an enigmatic human parasite that sickens thousands of people worldwide. The scarcity of research material and lack of any animal model or cell culture system slows research, denying the produce industry, epidemiologists, and regulatory agencies of tools that might aid diagnosis, risk assessment, and risk abatement. Fortunately, related species offer a strong foundation when used as surrogates to study parasites of this type. Species of Eimeria lend themselves especially well as surrogates for C. cayetanensis. Those Eimeria that infect poultry can be produced in abundance, share many biological features with Cyclospora, pose no risk to the health of researchers, and can be studied in their natural hosts. Here, we overview the actual and potential uses of such surrogates to advance understanding of C. cayetanensis biology, diagnostics, control, and genomics, focusing on opportunities to improve prevention, surveillance, risk assessment, and risk reduction. Studying Eimeria surrogates accelerates progress, closing important research gaps and refining promising tools for producers and food safety regulators to monitor and ameliorate the food safety risks imposed by this emerging, enigmatic parasite.

Dynamically expressed genes provide candidate viability biomarkers in a model coccidian

Eimeria parasites cause enteric disease in livestock and the closely related Cyclosporacayetanensis causes human disease. Oocysts of these coccidian parasites undergo maturation (sporulation) before becoming infectious. Here, we assessed transcription in maturing oocysts of Eimeria acervulina, a widespread chicken parasite, predicted gene functions, and determined which of these genes also occur in C. cayetanensis. RNA-Sequencing yielded ~2 billion paired-end reads, 92% of which mapped to the E. acervulina genome. The ~6,900 annotated genes underwent temporally-coordinated patterns of gene expression. Fifty-three genes each contributed >1,000 transcripts per million (TPM) throughout the study interval, including cation-transporting ATPases, an oocyst wall protein, a palmitoyltransferase, membrane proteins, and hypothetical proteins. These genes were enriched for 285 gene ontology (GO) terms and 13 genes were ascribed to 17 KEGG pathways, defining housekeeping processes and functions important throughout sporulation. Expression differed in mature and immature oocysts for 40% (2,928) of all genes; of these, nearly two-thirds (1,843) increased their expression over time. Eight genes expressed most in immature oocysts, encoding proteins promoting oocyst maturation and development, were assigned to 37 GO terms and 5 KEGG pathways. Fifty-six genes underwent significant upregulation in mature oocysts, each contributing at least 1,000 TPM. Of these, 40 were annotated by 215 GO assignments and 9 were associated with 18 KEGG pathways, encoding products involved in respiration, carbon fixation, energy utilization, invasion, motility, and stress and detoxification responses. Sporulation orchestrates coordinated changes in the expression of many genes, most especially those governing metabolic activity. Establishing the long-term fate of these transcripts in sporulated oocysts and in senescent and deceased oocysts will further elucidate the biology of coccidian development, and may provide tools to assay infectiousness of parasite cohorts. Moreover, because many of these genes have homologues in C. cayetanensis, they may prove useful as biomarkers for risk.

Fitness of artemisinin-resistant Plasmodium falciparum in vitro

OBJECTIVES

Drug resistance confers a fitness advantage to parasites exposed to frequent drug pressure, yet these mutations also may incur a fitness cost. We assessed fitness advantages and costs of artemisinin resistance in Plasmodium falciparum in vitro to understand how drug resistance will spread and evolve in a competitive environment.

METHODS

Genotyping of SNPs, drug susceptibility assays and copy number determination were used to assess the impact of artemisinin resistance on parasite fitness. An artemisinin-resistant clone (C9) selected in vitro from an isogenic parental clone (D6) was used to conduct competitive growth studies to assess fitness of artemisinin resistance. The resistant and susceptible clones were mixed or grown alone in the presence and absence of drug pressure (dihydroartemisinin or pyrimethamine) to quantify the rate at which artemisinin resistance was gained or lost.

RESULTS

We experimentally demonstrate for the first time that artemisinin resistance provides a fitness advantage that is selected for with infrequent exposure to drug, but is lost in the absence of exposure to artemisinin drugs. The best correlations with artemisinin resistance were decreased in vitro drug susceptibility to artemisinin derivatives, increased copy number of Pf3D7_1030100 and an SNP in Pf3D7_0307600. An SNP conferring an E208K mutation in the kelch gene (Pf3D7_1343700) was not associated with resistance. Furthermore, we observed second-cycle ring-stage dormancy induced by pyrimethamine, suggesting that dormancy is a fitness trait that provides an advantage for survival from antimalarial drug stress.

CONCLUSIONS

Artemisinin-resistant P. falciparum have a fitness advantage to survive and predominate in the population even in the face of infrequent exposure to artemisinin drugs.

Determination and quantification of Schistosoma mansoni cercarial emergence from Biomphalaria glabrata snails

Living and fixed samples of Schistosoma mansoni -infected Biomphalaria glabrata snails were used to determine the relative contributions of different snail tissues to cercarial emergence (shedding). Three methods of observations were employed: (1) direct microscopical observations of shedding snails; (2) microscopic analysis of 5 μm serial sections (H&E stained) of actively shedding snails; and (3) scanning electron microscopic (SEM) observations of snails that were fixed while actively shedding. For this investigation, there were advantages and disadvantages to using each method. We confirmed the results of others that there were 3 tissues of the snail that contributed most prominently to cercarial release (mantle collar, pseudobranch, and headfoot). Based on histological analysis of cercarial accumulations in presumed shedding sites in these 3 tissues, 57% of the cercariae could be seen in the mantle collar, 30.6% in the pseudobranch, and 12.5% in the headfoot. Other anterior structures were involved to a much lesser extent. SEM observations clearly showed cercariae emerging either body first, tail first, or likely emerging en masse from blebs, especially from the mantle collar. These studies provide a more quantitative appraisal of the role the different anterior snail tissues play in cercarial emergence.

Schistosomiasis

Schistosomiasis is the second most important parasitic disease in the world in terms of public health impact. Globally, it is estimated that the disease affects over 200 million people and is responsible for 200,000 deaths each year. The three major schistosomes infecting humans are Schistosoma mansoni, S. japonicum, and S. haematobium. Much immunological research has focused on schistosomiasis because of the pathological effects of the disease, which include liver fibrosis and bladder dysfunction. This unit covers a wide range of aspects with respect to maintaining the life cycles of these parasites, including preparation of schistosome egg antigen, maintenance of intermediate snail hosts, infection of the definitive and intermediate hosts, and others. The unit primarily focuses on S. mansoni, but also includes coverage of S. japonicum and S. haematobium life cycles.

Surveillance for enteric parasites among U.S. military personnel and civilian staff on Joint Task Force Base-Bravo in Soto Cano, Honduras and the local population in Comayagua and La Paz, Honduras

A study was conducted in Honduras to address whether military personnel assigned to Joint Task Force-Bravo in Soto Cano, Honduras, routinely acquire parasite infections, and the results were compared with those collected from civilian base workers and the general local population in the nearby towns of Comayagua and La Paz. Results from this study report 21 species of enteric parasites among Hondurans living in Comayagua and La Paz, 13 species among local Hondurans working as base civilian personnel, and 3 species among U.S. military servicemen and women. The most prevalent organism found was Blastocystis hominis, infecting 95 people (35.8% of 265 samples). Prevalence rates in this study are similar to documented reports on parasite transmission in Central American countries and other areas of Honduras. Although preventive protocols for U.S. military "force protection" appear to be effective in controlling transmission, continuous surveillance for enteric parasites is warranted because of the high parasite loads in the populations with which military personnel come into contact.

OBSERVATIONS OF BREINLIA BOOLIATI IN A NEW HOST, RATTUS RATTUS JALORENSIS, FROM KUANTAN, STATE OF PAHANG, MALAYSIA

Breinlia booliati Singh and Ho, 1973 is described from the Malaysian wood rat, Rattus rattus jalorensis Bonhote. The parasites presented here were originally discovered in 1955 in Kuantan, Malaysia, but were not classified until now. On the basis of morphological observations of anatomical structures and comparisons with other species of Breinlia, it was determined that the parasites were B. booliati. The parasites discussed here show slight deviation from B. booliati, but they do not warrant a new species classification. There is some variation in anatomical measurements, the number of male caudal papillae, and the morphology of the microfilariae. Breinlia booliati from a new host is described in this article, with a brief discussion on Rattus species that are hosts of B. booliati and vectors that transmit the parasite. The occurrence of B. booliati in R. r. jalorensis represents the first report of the parasite in this host.

Pressure, volume, and chemosensitivity in afferent innervation of urinary bladder in rats

Bladder afferent nerve activity was recorded from the pelvic and hypogastric nerves of rats anesthetized with pentobarbital sodium. Bladder filling with isotonic NaCl at a rate of 250 microl/min excited multiunit afferent activity in the hypogastric nerve by 190 +/- 38% over background at a pressure of 30 mmHg, whereas 150 meq/l KCl at the same filling rate excited hypogastric nerve activity by 498 +/- 103% (P < 0.0001). This difference was localized to a group of chemosensitive fibers that are excited by bladder filling with KCl in a concentration-dependent fashion but are insensitive to bladder filling with NaCl. Bladder filling with 200 meq/l KCl at different filling rates caused a bursting pattern of discharge in these fibers at consistent bladder volumes but with a pressure threshold that increased proportionately with filling rate. Other hypogastric bladder afferent fibers were activated to a similar extent by NaCl and KCl solutions. Chemoreceptive bladder afferent fibers were rare in the pelvic nerve (1 of 15 units), and multiunit preparations showed comparable excitations during bladder filling with NaCl and KCl solutions. The bursting activation of bladder chemoreceptive afferent nerves in hypogastric nerves could signal noxious overdistension and/or inflammation of the bladder.

Conditional immortalization of neuronal cells from postmitotic cultures and adult CNS

To determine whether postmitotic neurons can be immortalized by oncogenic transduction, we used two approaches involving conditional expression of a temperature-sensitive SV40 large T antigen (Tts). Initially, Tts was introduced into E17 rat embryonal hippocampal cells that were then cultured at the non-permissive temperature to enrich for postmitotic pyramidal neurons, and subsequently cloned at the permissive temperature. One clonal line (HMR10-3) expressed neuron-specific proteins upon differentiation, was capable of generating action potentials, and formed synapses with primary rat neurons in co-culture. Replating of these postmitotic cells at the permissive temperature resulted in reversible loss of neurofilament expression. Conditionally immortalized cell lines were also generated from the brain of an adult mouse carrying an inducible Tts transgene. These lines proliferated in a T antigen-dependent manner and expressed neuron-specific proteins upon differentiation at the non-permissive temperature. These results suggest that postmitotic neurons can be induced to enter the cell cycle without losing their commitment to a neuronal lineage.

Localization of immunoreactive epidermal growth factor receptor in neonatal and adult rat hippocampus

The regional and developmental expression of epidermal growth factor (EGF) receptor in rat hippocampus was investigated utilizing immunocytochemical techniques at the light and electron microscopic levels. EGF receptor immunoreactivity in adult hippocampus was compared to that found at postnatal day 7 (P7). While the receptor was observed in P7 hippocampus, immunostaining was more prominent in the adult hippocampus, especially in the pyramidal CA2 field. Ultrastructural analysis of this region revealed that the receptor was localized to the cell bodies of both P7 and adult neurons rather than the axons or dendrites. The expression of EGF receptor in selected regions of the adult brain was verified by Western blotting. These results demonstrate the presence of EGF receptor in rat hippocampus as early as P7, localize the receptor to the pyramidal cell body, and establish the hippocampal formation, particularly CA2, as a major site of EGF receptor expression in rat brain.

Activation of mitogen-activated protein kinase by epidermal growth factor in hippocampal neurons and neuronal cell lines

Epidermal growth factor (EGF) functions in a bimodal capacity in the nervous system, acting as a mitogen in neuronal stem cells and a neurotrophic factor in differentiated adult neurons. Thus, it is likely that EGF signal transduction, as well as receptor expression, differs among various cell types and possibly in the same cell type at different stages of development. We used hippocampal neuronal cell lines capable of terminal differentiation to investigate changes in EGF receptor expression, DNA synthesis, and stimulation of mitogen-activated protein (MAP) kinase by EGF before and after differentiation. H19-7, the line that was most representative of hippocampal neurons, was mitogenically responsive to EGF only before differentiation and increased in EGF binding after differentiation. MAP kinase was stimulated by EGF in both undifferentiated and differentiated cells, as well as in primary hippocampal cultures treated with either EGF or glutamate. These results indicate that the activation of MAP kinase by EGF is an early signaling event in both mitotic and postmitotic neuronal cells. Furthermore, these studies demonstrate the usefulness of hippocampal cell lines as a homogeneous neuronal system for studies of EGF signaling or other receptor signaling mechanisms in the brain.

Immortal rat hippocampal cell lines exhibit neuronal and glial lineages and neurotrophin gene expression

Clonal cell lines of rat embryonic hippocampal origin have been developed by using retroviral transduction of temperature-sensitive simian virus 40 large tumor antigens. The cell lines undergo morphological differentiation at the nonpermissive temperature and in response to differentiating agents. Immunocytochemical analysis indicates that various lines are derived from progenitors of neuronal, glial, and bipotential lineages. Selected neuronal lines differentiate in response to diffusible factors released by primary glia, and one line of glial lineage supports the maturation of primary neurons in culture. Selected cell lines exhibit different patterns of neurotrophin gene expression that change after differentiation. In some lines, the relative levels of neurotrophin 3 and brain-derived neurotrophic factor message expression may reflect the developmental or regional differential expression seen for these genes in the hippocampus in situ. These hippocampal cell lines, which express markers indicative of commitment to neuronal or glial lineages, are valuable for studies of development and plasticity in these lineages, as well as for studies of the regulation of neural trophic interactions.

Diverticula of the female urethra: diagnosis by endovaginal and transperineal sonography

Diverticula of the female urethra can be difficult to diagnose. Invasive contrast studies (voiding cystourethrography or double-balloon urethrography) or urethroscopy are frequently required for definitive diagnosis. Although transabdominal sonography has been able to visualize large diverticula, this technique has not proved useful in routine screening. In this study, we examined the use of higher frequency (5 MHz) near-focus endovaginal or transperineal sonography for the diagnosis of urethral diverticula. Five patients with radiographically proved (three with double-balloon urethrography and two with voiding cystourethrography) urethral diverticula were examined with endovaginal (two cases) or transperineal (four cases) sonography. In all five cases, sonography showed the diverticula previously demonstrated on the contrast study. The spatial relationship of the diverticula to the urethra, an important consideration at surgery, was shown more clearly by sonography than by contrast radiography. These findings suggest that sonography may be useful as a noninvasive screening technique for urethral diverticula.

Blunt trauma of uterovaginal and vesical prolapse with associated bladder rupture

A 71-year-old woman had complete uterovaginal and vesical prolapse associated with a large decubitus ulcer on the anterior vaginal wall. She sustained blunt trauma to the perineum after a fall, which resulted in rupture of the prolapsed bladder. The management of this rare problem is discussed.

Mechanism of renin release in exercising dog

Exercise is associated with an increase in plasma renin activity (PRA). The purpose of this study was to determine the role of the prostaglandin (PG) and adrenergic pathways in the renin release with exercise in the dog. One group of animals (n = 4) was exercised under control untreated and indomethacin- and meclofenamate- (2 mg/kg) treated conditions. A 155% increase in PRA was not influenced by PG inhibition. In a second group (n = 7) PRA was 1.22 +/- 0.32, 3.29 +/- 1.59, 6.28 +/- 2.85, and 5.30 +/- 2.00 ng ANG I X ml-1 X h-1 at rest and during light, moderate, and heavy exercise, respectively. Guanethidine treatment (15 mg/kg) decreased mean PRA by 41, 50, 70, and 73% at rest and during the three levels of exercise, respectively. In a third group (n = 5) control exercise runs were repeated after metoprolol treatment. Selective beta 1-blockade completely abolished the increment in PRA observed with exercise. These data demonstrate that the elevation of PRA during exercise in the dog is mediated by increased sympathetic nerve activity involving beta 1-receptors and that it is not dependent on alterations in PG synthesis.

The use of the systolic time interval for predicting left ventricular ejection fraction ischemic heart disease

A large series of 306 patients with ischemic heart disease was studied with automated systolic time intervals and left ventricular ejection fraction as determined by the angiocardiographic method. It was found the pre-ejection period, left ventricular ejection time, delta values, and PEP/LVET ratio all were related to the ejection fraction. However, in all instances the correlation was too low and the scatter of the data was too large to warrant the use of the systolic time intervals for predicting left ventricular function as indicated by the ejection fraction.