Identification of blood source preferences and Leishmania infection in sand flies (Diptera: Psychodidae) in north-eastern Algeria

Leishmaniases are among the most neglected vector-borne diseases, infecting humans as well various animal hosts with clinical outcomes varying from cutaneous disorders to visceral and life-threatening disease. In Algeria, canine leishmaniasis (CanL) caused by Leishmania infantum is endemic mainly throughout the northern regions of the country with the Mediterranean climate that favours the occurrence of Larroussius sand flies, the vectors of the parasite. This study conducted in Bougaa and Kherrata, two regions located in north-eastern Algeria and endemic for CanL, focuses on: i) composition of sand fly fauna, ii) screening of Leishmania parasites and iii) the blood sources of engorged females. Entomological surveys were conducted between June and September 2019 using CDC light-traps in rural areas of both regions. Sand fly specimens were morphologically identified, females were screened for Leishmania DNA using kDNA and ITS1 primers, blood meals in engorged females were identified by peptide mass mapping (PMM)-based MALDI-TOF mass spectrometry and confirmed by DNA sequencing analysis. Overall, 1940 specimens (844 males, 1096 females) were collected, all belonging to the subgenus Larroussius: Phlebotomus perniciosus, (94.64%), Ph. perfiliewi (4.74%) and Ph. longicuspis (0.62%). No Leishmania DNA was detected in the evaluated pools (n = 106) (1096 females). PMM-based MALDI-TOF MS successfully identified a source of blood in 92% (141/154) of engorged females (135 Ph. perniciosus and 6 Ph. perfiliewi). All blood meals were taken from domestic cattle (Bos taurus) except for one originating from a dog (Canis lupus familiaris) and one from sheep (Ovis aries). Sequencing of host cytochrome B gene confirmed these identifications but showed lower success rate of 58% (29/50), demonstrating the high effectivity of peptide mass mapping (PMM)-based MALDI-TOF mass spectrometry for routine identification of blood meals of varying degree of digestion. Our findings represent first record of cattle and dog blood in sand flies in Algeria and striking feeding preference of local sand fly population at domestic sites of studied regions for cattle which may play an important role in parasite transmission. Further studies are needed to better understand potential contribution of cattle to ecology of sand flies and epidemiology of leishmaniasis in north-eastern Algeria.

Prevalence and risk factors of intestinal protozoan infection among symptomatic and asymptomatic populations in rural and urban areas of southern Algeria

BACKGROUND

Intestinal parasitic infections are amongst the most common infections worldwide and have been identified as one of the most significant causes of morbidity and mortality among disadvantaged populations. This comparative cross-sectional study was conducted to assess the prevalence of intestinal protozoan infections and to identify the significant risk factors associated with intestinal parasitic infections in Laghouat province, Southern Algeria.

METHODS

A comparative cross-sectional study was conducted, involving 623 symptomatic and 1654 asymptomatic subjects. Structured questionnaires were used to identify environmental, socio demographic and behavioral factors. Stool specimens were collected and examined using direct wet mount, formalin-ether concentration, xenic in vitro culture and staining methods.

RESULTS

A highly significant difference of prevalence was found between symptomatic (82.3%) and asymptomatic subjects (14.9%), with the majority attributable to protozoan infection. The most common species in the symptomatic subjects were Blastocystis spp. (43.8%), E. histolytica/dispar (25.4%) and Giardia intestinalis (14.6%) and more rarely Enterobius vermicularis (02.1%), Teania spp. (0.6%) and Trichuris trichiura (0.2%), while in asymptomatic population Blastocystis spp. (8%), Entamoeba coli (3.3%) and Entamoeba histolytica/dispar (2.5%) were the most common parasites detected with no case of helminth infection. Multivariate log-linear analysis showed that contact with animals was the main risk factor for transmission of these protozoa in both populations. Furthermore, living in rural areas was significantly associated with combined protozoan infection in the asymptomatic population, whereas, in the symptomatic population an increasing trend of protozoan infection was detected in the hot season. In addition, Blastocystis spp. and G. intestinalis infection were found to be associated with host sex and contact with animals across the study period.

CONCLUSIONS

Based on these results, several strategies are recommended in order to effectively reduce these infections including good animal husbandry practices, health education focused on good personal hygiene practices and adequate sanitation.

Prevalence and Clinical Manifestations of Giardia intestinalis and Other Intestinal Parasites in Children and Adults in Algeria

Giardia intestinalis is one of the most common causes of parasite-induced diarrhea, abdominal pain, flatulence, and malabsorption. Yet, data on the epidemiology of G. intestinalis infections in North Africa are limited. The purpose of this study was to carry out a retrospective survey on the level of intestinal parasitism with a particular emphasis on G. intestinalis in children and adults in Algiers, Algeria. A total of 2,054 individuals from outpatient clinics or hospitalized at Beni-Messous University Hospital of Algiers undergoing stool microscopy for ova and parasites were included. The overall parasite infection rate was 28%. In the 567 parasite-positive samples, Blastocystis was found most frequently (57.3%), followed in frequency by Endolimax nana (41.0%), Entamoeba histolytica/dispar (19.6%), G. intestinalis (17.1%), Entamoeba coli (13.9%), Chilomastix mesnili (1.0%), Iodamoeba bütschlii (0.7%), Entamoeba hartmanni (0.5%), and Cryptosporidium spp. (0.2%). Intestinal parasites were generally more common in adults than in children, except for Giardia, which was more common in children (P = 0.0001). Giardia infection was independent of gender (P = 0.94). Compared with other intestinal parasitic infections, clinical manifestations, such as abdominal pain (P = 0.28) and diarrhea (P = 0.82), were found not to be significantly linked to Giardia infection. In conclusion, G. intestinalis is common in individuals referred to the University Hospital of Beni-Messous with digestive symptoms, particularly so in children. However, in our study, intestinal symptoms appeared not to be more linked to Giardia than to other intestinal parasites.

Occurrence and molecular characterization of Giardia duodenalis in lambs in Djelfa, the central steppe of Algeria

Little is known of the prevalence and genetic identity of Giardia duodenalis in sheep in Algeria. The present study aimed at characterizing G. duodenalis in lambs up to 6 months of age in Djelfa, Algeria. A total of 346 fecal specimens were collected from 28 farms and screened for G. duodenalis cysts by zinc sulfate flotation microscopy, and positive specimens were confirmed using a direct immunofluorescence assay. Microscopy-positive specimens were analyzed by PCR and sequence analysis of the triosephosphate isomerase and glutamate dehydrogenase genes to determine G. duodenalis assemblages. Coprological examination indicated that the overall infection rate was 7.0% (24/346). Lambs under 3 months of age had higher infection rate (18/197, 9.0%) than older (6/149, 4.0%) animals, and animals with diarrhea (7/44, 16.0%) had higher infection rate than animals without diarrhea (17/302, 5.6%). PCR sequence analyses of the 15 G. duodenalis isolates revealed the presence of assemblages A in 6 isolates, assemblage E in 7 isolates, and both in 2 isolates. Assemblage A was only found in pre-weaned lambs with diarrhea, while assemblage E was mostly found in post-weaned lambs without diarrhea. The assemblage E isolates from sheep were genetically related to those from cattle in Algeria, while assemblage A isolates were from a well-known subtype prevalent in humans. Data generated from the study improve our understanding of the transmission of G. duodenalis in Algeria.

Zoonotic Cryptosporidium species and subtypes in lambs and goat kids in Algeria

BACKGROUND

Little is known on the occurrence and identity of Cryptosporidium species in sheep and goats in Algeria. This study aimed at investigating the occurrence of Cryptosporidium species in lambs and goat kids younger than 4 weeks.

METHODS

A total of 154 fecal samples (62 from lambs and 92 from kid goats) were collected from 13 sheep flocks in Médea, Algeria and 18 goat flocks across Algiers and Boumerdes. They were screened for Cryptosporidium spp. by nested-PCR analysis of a fragment of the small subunit (SSU) rRNA gene, followed by restriction fragment length polymorphism and sequence analyses to determine the Cryptosporidium species present. Cryptosporidium parvum and C. ubiquitum were further subtyped by sequence analysis of the 60 kDa glycoprotein gene.

RESULTS

Cryptosporidium spp. were detected in 17 fecal samples (11.0%): 9 from lambs (14.5%) and 8 from goat kids (8.7%). The species identified included C. parvum in 3 lambs, C. xiaoi in 6 lambs and 6 goat kids, and C. ubiquitum in 2 goat kids. Cryptosporidium infections were detected mostly in animals during the first two weeks of life (7/8 for goat kids and 7/9 for lambs) and in association with diarrhea occurrence (7/17 or 41.2% goat kids and 7/10 or 70.0% lambs with diarrhea were positive for Cryptosporidium spp.). Subtyping of C. parvum and C. ubiquitum isolates identified the zoonotic IIaA13G2R1 and XIIa subtype families, respectively. Minor differences in the SSU rRNA gene sequences were observed between C. xiaoi from sheep and goats.

CONCLUSIONS

Results of this study indicate that three Cryptosporidium species occur in lambs and goat kids in Algeria, including zoonotic C. parvum and C. ubiquitum. They are associated with the occurrence of neonatal diarrhea.

Prevalence of Cryptosporidium spp. in farmed animals from steppe and high plateau regions in Algeria

This study was conducted to investigate the prevalence of Cryptosporidium spp. and associated potential risk factors in farmed animals from different steppe and high plateau regions in Algeria. A total of 289, 254 and 149 faecal samples of cattle, sheep and dromedary camels respectively, and tracheas of 135 broiler chickens were screened for the presence of Cryptosporidium spp. by formalin-ether concentration method and modified Ziehl-Neelsen staining. Overall, Cryptosporidium spp. was detected in 36.7%, 15%, 8.9% and 2% of examined cattle, sheep, broiler chickens and dromedary camels. In cattle, the highest prevalence was observed in the neonatal calves (52.6%) and the presence of Cryptosporidium spp. was significantly associated with diarrhoea. Ovine cryptosporidiosis was found in more of 80% of sampled farms and lambs aged between 1-6 months (20.3%), followed by neonatal lambs (18.7%) were the most infected. Cryptosporidium excretion in sheep was not associated with presence of diarrhoea. The presence of cryptosporidia in broiler chickens showed a higher rate in birds aged of 16-24 days (30%) than in those of 35-44 days (3.5%). None of broiler chickens more than 44 days was found to be positive for Cryptosporidium. Cryptosporidium in dromedary camels was reported in three females aged more than 6 months, which did not show any signs of diarrhoea at the time of sampling. Cryptosporidium prevalence was not affected by sex in all studied animal species. The results of the present study provide the first data on the prevalence of Cryptosporidium spp. in dromedary camels and broiler chickens from steppe and high plateau regions in Algeria.

Molecular characterization of zoonotic pathogens Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi in calves in Algeria

Little is known on the identity and public health potential of Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi in farm animals in Algeria. In this study, 102 fecal specimens from pre-weaned dairy calves with or without diarrhea were collected from 19 dairy farms located in 6 provinces. PCR-restriction fragment length polymorphism analysis of the small subunit rRNA gene was used to detect and differentiate Cryptosporidium spp., whereas PCR-sequence analysis of the triosephosphate isomerase gene and ribosomal internal transcribed spacer were used to detect and genotype G. duodenalis and E. bieneusi, respectively. Cryptosporidium was found in 14 specimens, among which 7 had C. parvum, 4 had C. bovis, and 3 had mixed infection of C. parvum and C. bovis or C. bovis and C. andersoni. Subtyping of C. parvum by PCR-sequence analysis of the 60kDa glycoprotein gene identified two zoonotic subtypes IIaA16G2R1 and IIaA17G3R1. G. duodenalis was found in 28 specimens, with 6 having the host-specific assemblage E, 14 having the zoonotic assemblage A (all belonging to A2 subtype), and 8 having mixed assemblages. Six known genotypes of E. bieneusi belonging to Group 2, including I, J, BEB3, BEB4, BEB6 and PtEb XI, were identified in 11 specimens. Diarrhea was mostly associated with the occurrence of C. parvum. Data from this study suggest that human-pathogenic C. parvum subtypes and G. duodenalis and E. bieneusi genotypes are common on dairy farms in Algeria.

Rad54 and Mus81 cooperation promotes DNA damage repair and restrains chromosome missegregation

Rad54 and Mus81 mammalian proteins physically interact and are important for the homologous recombination DNA repair pathway; however, their functional interactions in vivo are poorly defined. Here, we show that combinatorial loss of Rad54 and Mus81 results in hypersensitivity to DNA-damaging agents, defects on both the homologous recombination and non-homologous DNA end joining repair pathways and reduced fertility. We also observed that while Mus81 deficiency diminished the cleavage of common fragile sites, very strikingly, Rad54 loss impaired this cleavage to even a greater extent. The inefficient repair of DNA double-strand breaks (DSBs) in Rad54(-/-)Mus81(-/-) cells was accompanied by elevated levels of chromosome missegregation and cell death. Perhaps as a consequence, tumor incidence in Rad54(-/-)Mus81(-/-) mice remained comparable to that in Mus81(-/-) mice. Our study highlights the importance of the cooperation between Rad54 and Mus81 for mediating DNA DSB repair and restraining chromosome missegregation.

Brca1 required for T cell lineage development but not TCR loci rearrangement

Brca1 (breast cancerl, early onset) deficiency results in early embryonic lethality. As Brca1 is highly expressed in the T cell lineage, a T cell-specific disruption of Brca1 was generated to assess the role of Brca1 in relation to T lymphocyte development. We found that thymocyte development in Brca1-/- mice was impaired not as a result of V(D)J T cell receptor (TCR) recombination but because thymocytes had increased expression of tumor protein p53. Chromosomal damage accumulation and abnormal cell death were observed in mutant cells. We found that cell death inhibitor Bcl-2 overexpression, or p53-/- backgrounds, completely restored survival and development of Brca1-/- thymocytes; peripheral T cell numbers were not totally restored in Brcal-/- p53-/- mice; and that a mutant background for p21 (cyclin-dependent kinase inhibitor 1A) did not restore Brca1-/- thymocyte development, but partially restored peripheral T cell development. Thus, the outcome of Brca1 deficiency was dependent on cellular context, with the major defects being increased apoptosis in thymocytes, and defective proliferation in peripheral T cells.

In vivo evidence that caspase-3 is required for Fas-mediated apoptosis of hepatocytes

Caspase-3 is essential for Fas-mediated apoptosis in vitro. We investigated the role of caspase-3 in Fas-mediated cell death in vivo by injecting caspase-3-deficient mice with agonistic anti-Fas Ab. Wild-type controls died rapidly of fulminant hepatitis, whereas the survival of caspase-3-/- mice was increased due to a delay in hepatocyte cell death. Bcl-2 expression in the liver was dramatically decreased in wild-type mice following anti-Fas injection, but was unchanged in caspase-3-/- mice. Hepatocytes from anti-Fas-injected wild-type, but not caspase-3-/-, mice released cytochrome c into the cytoplasm. Western blotting confirmed the lack of caspase-3-mediated cleavage of Bcl-2. Presumably the presence of intact Bcl-2 in caspase-3-/- hepatocytes prevents the release of cytochrome c from the mitochondria, a required step for the mitochondrial death pathway. We also show by Western blot that Bcl-xL, caspase-9, caspase-8, and Bid are processed by caspase-3 in injected wild-type mice but that this processing does not occur in caspase-3-/- mice. This study thus provides novel in vivo evidence that caspase-3, conventionally known for its downstream effector function in apoptosis, also modifies Bcl-2 and other upstream proteins involved in the regulation of Fas-mediated apoptosis.

The cyclin-dependent kinase Cdk2 regulates thymocyte apoptosis

Aberrant activation of cell cycle molecules has been postulated to play a role in apoptosis ("catastrophic cell cycle"). Here we show that in noncycling developing thymocytes, the cyclin- dependent kinase Cdk2 is activated in response to all specific and nonspecific apoptotic stimuli tested, including peptide-specific thymocyte apoptosis. Cdk2 was found to function upstream of the tumor suppressor p53, transactivation of the death promoter Bax, alterations of mitochondrial permeability, Bcl-2, caspase activation, and caspase-dependent proteolytic cleavage of the retinoblastoma protein. Inhibition of Cdk2 completely protected thymocytes from apoptosis, mitochondrial changes, and caspase activation. These data provide the first evidence that Cdk2 activity is crucial for the induction of thymocyte apoptosis.

Apaf1 is required for mitochondrial pathways of apoptosis and brain development

Apoptosis is essential for the precise regulation of cellular homeostasis and development. The role in vivo of Apaf1, a mammalian homolog of C. elegans CED-4, was investigated in gene-targeted Apaf1-/- mice. Apaf1-deficient mice exhibited reduced apoptosis in the brain and striking craniofacial abnormalities with hyperproliferation of neuronal cells. Apaf1-deficient cells were resistant to a variety of apoptotic stimuli, and the processing of Caspases 2, 3, and 8 was impaired. However, both Apaf1-/- thymocytes and activated T lymphocytes were sensitive to Fas-induced killing, showing that Fas-mediated apoptosis in these cells is independent of Apaf1. These data indicate that Apaf1 plays a central role in the common events of mitochondria-dependent apoptosis in most death pathways and that this role is critical for normal development.

Differential requirement for caspase 9 in apoptotic pathways in vivo

Mutation of Caspase 9 (Casp9) results in embryonic lethality and defective brain development associated with decreased apoptosis. Casp9-/- embryonic stem cells and embryonic fibroblasts are resistant to several apoptotic stimuli, including UV and gamma irradiation. Casp9-/- thymocytes are also resistant to dexamethasone- and gamma irradiation-induced apoptosis, but are surprisingly sensitive to apoptosis induced by UV irradiation or anti-CD95. Resistance to apoptosis is accompanied by retention of the mitochondrial membrane potential in mutant cells. In addition, cytochrome c is translocated to the cytosol of Casp9-/- ES cells upon UV stimulation, suggesting that Casp9 acts downstream of cytochrome c. Caspase processing is inhibited in Casp9-/- ES cells but not in thymocytes or splenocytes. Comparison of the requirement for Casp9 and Casp3 in different apoptotic settings indicates the existence of at least four different apoptotic pathways in mammalian cells.

Essential contribution of caspase 3/CPP32 to apoptosis and its associated nuclear changes

Caspases are fundamental components of the mammalian apoptotic machinery, but the precise contribution of individual caspases is controversial. CPP32 (caspase 3) is a prototypical caspase that becomes activated during apoptosis. In this study, we took a comprehensive approach to examining the role of CPP32 in apoptosis using mice, embryonic stem (ES) cells, and mouse embryonic fibroblasts (MEFs) deficient for CPP32. CPP32(ex3-/-) mice have reduced viability and, consistent with an earlier report, display defective neuronal apoptosis and neurological defects. Inactivation of CPP32 dramatically reduces apoptosis in diverse settings, including activation-induced cell death (AICD) of peripheral T cells, as well as chemotherapy-induced apoptosis of oncogenically transformed CPP32(-/-) MEFs. As well, the requirement for CPP32 can be remarkably stimulus-dependent: In ES cells, CPP32 is necessary for efficient apoptosis following UV- but not gamma-irradiation. Conversely, the same stimulus can show a tissue-specific dependence on CPP32: Hence, TNFalpha treatment induces normal levels of apoptosis in CPP32 deficient thymocytes, but defective apoptosis in oncogenically transformed MEFs. Finally, in some settings, CPP32 is required for certain apoptotic events but not others: Select CPP32(ex3-/-) cell types undergoing cell death are incapable of chromatin condensation and DNA degradation, but display other hallmarks of apoptosis. Together, these results indicate that CPP32 is an essential component in apoptotic events that is remarkably system- and stimulus-dependent. Consequently, drugs that inhibit CPP32 may preferentially disrupt specific forms of cell death.

The interferon regulatory transcription factor IRF-1 controls positive and negative selection of CD8+ thymocytes

Little is known about the molecular mechanisms and transcriptional regulation that govern T cell selection processes and the differentiation of CD4+ and CD8+ T cells. Mice lacking the interferon regulatory transcription factor-1 (IRF-1) have reduced numbers of mature CD8+ cells within the thymus and peripheral lymphatic organs. Here we show that positive and negative T cell selection of two MHC class I-restricted TCR alphabeta transgenes, H-Y and P14, are impaired in IRF-1-/- mice. The absence of IRF-1 resulted in decreased expression of LMP2, TAP1, and MHC class I on thymic stromal cells. Despite decreased MHC class I expression on IRF-1-/- thymic stromal cells, the defect in CD8+ T cells development did not reside in the thymic environment, and IRF-1-/- stromal cells can fully support development of CD8+ thymocytes in in vivo bone marrow chimeras and in vitro reaggregation cultures. Moreover, IRF-1-/- thymocytes displayed impaired TCR-mediated signal transduction, and the induction of negative selection in TCR Tg thymocytes from IRF-1-/- mice required a 1000-fold increase in selecting peptide. We also provide evidence that IRF-1 is mainly expressed in mature, but not immature, thymocytes and that expression of IRF-1 in immature thymocytes is induced after peptide-specific TCR activation. These results indicate that IRF-1 regulates gene expression in developing thymocytes required for lineage commitment and selection of CD8+ thymocytes.

The tumor suppressor gene Brca1 is required for embryonic cellular proliferation in the mouse

Mutations of the BRCA1 gone in humans are associated with predisposition to breast and ovarian cancers. We show here that Brca1+/- mice are normal and fertile and lack tumors by age eleven months. Homozygous Brca1(5-6) mutant mice die before day 7.5 of embryogenesis. Mutant embryos are poorly developed, with no evidence of mesoderm formation. The extraembryonic region is abnormal, but aggregation with wild-type tetraploid embryos does not rescue the lethality. In vivo, mutant embryos do not exhibit increased apoptosis but show reduced cell proliferation accompanied by decreased expression of cyclin E and mdm-2, a regulator of p53 activity. The expression of cyclin-dependent kinase inhibitor p21 is dramatically increased in the mutant embryos. Buttressing these in vivo observations is the fact that mutant blastocyst growth is grossly impaired in vitro. Thus, the death of Brca1(5-6) mutant embryos prior to gastrulation may be due to a failure of the proliferative burst required for the development of the different germ layers.

Impaired negative selection of T cells in Hodgkin's disease antigen CD30-deficient mice

CD30 is found on Reed-Sternberg cells of Hodgkin's disease and on a variety of non-Hodgkin's lymphoma cells and is up-regulated on cells after Epstein-Barr virus, human T cell leukemia virus, and HIV infections. We report here that the thymus in CD30-deficient mice contains elevated numbers of thymocytes. Activation-induced death of thymocytes after CD3 cross-linking is impaired both in vitro and in vivo. Breeding the CD30 mutation separately into alpha beta TCR-or gamma delta TCR-transgenic mice revealed a gross defect in negative but not positive selection. Thus, like TNF-receptors and Fas/Apo-1, the CD30 receptor is involved in cell death signaling. It is also an important coreceptor that participates in thymic deletion.