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Aims: To determine the toxicity of astemizole-methylene blue combination therapy as effective candidates for therapeutic repurposing against malaria. Study Design: Randomized block study design. Place and Duration of Study: Department of Tropical and Infectious Diseases, Institute of Primate Research, between July and December, 2019. Methodology: The Lorke’s technique was used to evaluate the toxicity of the drug combinations in Balb/c mice (N=25). The mice were monitored for clinical signs at 2-hour intervals. After 48 hours, the mice were euthanized, and their tissues collected, weighed and grossly examined. Biochemistry and hematological tests were performed after blood samples were collected. Analysis of Variance and the t-test were used for statistical analysis; differences were considered significant if P values were less than 0.05 (p˂ 0.05). Results: The findings revealed that mice treated with methylene blue alone experienced a decrease of appetite, while mice treated with astemizole alone experienced slight tremors, which were not observed in the medication combined groups. When compared to the negative controls, the astemizole-methylene blue 3:1 combination group exhibited reduced heart (p=0.007) and liver (p=0.0001) mean weights. Platelet levels in the astemizole-methylene blue 3:1 group were lower in comparison to the other groups (p=0.005), according to the hematological data collected. Conclusion: When delivered in ratios with less astamizole, astemizole-methylene blue combination therapy showed better results in terms of safety than monotherapy with either drug alone.

Naturally acquired immunity to malaria develops over several years and can be compromised by concomitant infections. This study explored the influence of chronic schistosomiasis on clinical outcome and immunity to repeated malaria infection. Two groups of baboons (n = 8 each), were infected with Schistosoma mansoni cercariae to establish chronic infections. One of the two groups was treated with praziquantel (PZQ) to eliminate schistosome infection. The two groups plus a new malaria control group (n = 8) were inoculated three times with Plasmodium knowlesi parasites at 1-month intervals. Clinical data and IgG, IgG1, memory T-cell, and monocyte levels were recorded. After three P. knowlesi infections, we observed (i) reduced clinical symptoms in all groups with each subsequent infection, (ii) increased IgG and IgG1 levels in the malaria control (Pk-only) group, (iii) increased IgG, IgG1, CD14(+), and CD14(−) CD16(+) levels in the Schistosoma-treated (Schisto/PZQ+Pk) group, and (iv) significantly lower IgG and IgG1 levels compared to those of the Pk-only group, reduced CD4(+) CD45RO(+) levels, and increased levels of CD14(−) CD16(+) cells in the coinfected (Schisto+Pk) group. Chronic S. mansoni infection does not compromise establishment of clinical immunity after multiple malaria infections, with nonclassical monocytes seeming to play a role. Failure to develop robust antibody and memory T cells may have a long-term impact on acquired immunity to malaria infection.

Intranasal instillation of SE36, a malaria vaccine candidate antigen, in lactating BALB/c strain (derived from the Bagg and albino laboratory inbred mice) female mice resulted in the appearance of the antigen in breast milk as demonstrated by sandwich ELISA and Western blot. Pups born of immunologically naive mice and breastfed on lactating foster mothers exposed intranasally to SE36 developed IgG anti-SE36 antibodies. These data demonstrate that maternal immunization in mice by this route in lactating mothers can result in active immunization of offspring via ingestion of breast milk containing antigen. If confirmed in a nonhuman primate model and in human subjects, this strategy might be transformative for vaccination against malaria and other infant killer infectious diseases.

The study aimed to characterize phytochemical composition of C. maxima seeds and pulp. The ethanol and aqueous extract of C. maxima seeds and pulp were done using percolation method. The phytochemical composition of ethanol and aqueous extract were determined using methodology described by the association of official analytical chemists. Qualitative screening of both aqueous and ethanol seed and pulp extracts showed presence of alkaloids, flavanoids, phenolics, carbohydrates, tannins, saponins, terpenoids and proteins. The quantitative tests reported concentration of 0.336g/100g of phenols, 0.012g/100g flavanoids and 0.009g/100g tannins in seed aqueous extracts while 0.213g/100g, 0.175g/100g and 0.016/100g in pulp respectively. The levels of phenols, flavanoids and tannins reported in ethanol extracts were 0.277g/100g, 0.246g/100g and 0.010g/100g in pulp and 0.530g/100g, 0.252g/100g and 0.064g/100g in seed respectively. Saponins were present in ethanol extracts only. The percentage content of alkaloids was 4.9% in pulp and 5.97% in seed aqueous extracts while ethanol pulp and seed extracts was 9.49% and 9.74% respectively. All extracts showed significant levels of anti-oxidant activity at different concentration levels. The presence of these phytochemical compounds shows that C. maxima are a potential medicinal candidate that needs to be explored further for actual use as in pharmaceutical industry.

Incorporation of biomolecular epitopes to malarial antigens should be explored in the development of strain-transcending malarial vaccines. The present study sought to determine safety, immunogenicity and cross-species efficacy ofPlasmodium falciparum serine repeat antigen 5 polypeptide co-expressed with epitopes of Bacille-Calmette Guerin (BCG), tetanus toxoid (TT) and a chemokine gene. Olive baboons and BALB/c mice were randomly assigned into vaccine and control groups. The vaccine group animals were primed and boosted twice with pIRES plasmids encoding the SERA5+ BCG+ TT alone, or with either CCL5 or CCL20 and the control group with pIRES plasmid vector backbone. Mice and baboons were challenged withP. berghei ANKA and P. knowlesi H strain parasites, respectively. Safety was determined by observing for injection sites reactogenicities, hematology and clinical chemistry. Parasitaemia and survivorship profiles were used to determine cross-species efficacy, and T cell phenotypes, Th1-, Th2-type, T-regulatory immune responses and antibody responses were assessed to determine vaccine immunogenicity. The pSeBCGTT plasmid DNA vaccines were safe and induced Th1-, Th2-type, and T-regulatory responses vaccinated animals showed enhanced CD4+ (P

Introduction: Chemotherapy still is the most effective way to control malaria, a major public health problem in sub-Saharan Africa. The large-scale use of the combination therapy artemether-lumefantrine for malaria treatment in Africa predisposes lumefantrine to emergence of resistance. There is need to identify drugs that can be used as substitutes to lumefantrine for use in combination therapy. Methylene blue, a synthetic anti-methemoglobinemia drug, has been shown to contain antimalarial properties, making it a candidate for drug repurposing. The present study sought to determine antiplasmodial effects of methylene blue against lumefantrine- and pyrimethamine-resistant strains of P. berghei. Methodology: Activity of methylene blue was assessed using the classical four-day test on mice infected with lumefantrine-resistant and pyrimethamine-resistant P. berghei. A dose of 45 mg/kg/day was effective for testing ED90. Parasitemia and mice survival was determined. Results: At 45 mg/kg/day, methylene blue sustained significant parasite inhibition, over 99%, for at least 6 days post-treatment against lumefantrine-resistant and pyrimethamine-resistant P. berghei (p = 0.0086 and p = 0.0191, respectively). No serious adverse effects were observed. Conclusions: Our results indicate that methylene blue at a concentration of 45 mg/kg/day confers over 99% inhibition against lumefantrine- and pyrimethamine-resistant P. berghei for six days. This shows the potential use methylene blue in the development of antimalarials against lumefantrine- and pyrimethamine-resistant parasites.

Background Antivenom is the treatment of choice for snakebite, which annually kills an estimated 32,000 people in sub-Saharan Africa and leaves approximately 100,000 survivors with permanent physical disabilities that exert a considerable socioeconomic burden. Over the past two decades, the high costs of the most polyspecifically-effective antivenoms have sequentially reduced demand, commercial manufacturing incentives and production volumes that have combined to create a continent-wide vacuum of effective snakebite therapy. This was quickly filled with new, less expensive antivenoms, many of which are of untested efficacy. Some of these successfully marketed antivenoms for Africa are inappropriately manufactured with venoms from non-African snakes and are dangerously ineffective. The uncertain efficacy of available antivenoms exacerbates the complexity of designing intervention measures to reduce the burden of snakebite in sub-Saharan Africa. The objective of this study was to preclinically determine the ability of antivenoms available in Kenya to neutralise the lethal effects of venoms from the most medically important snakes in East Africa. Methods We collected venom samples from the most medically important snakes in East Africa and determined their toxicity in a mouse model. Using a ‘gold standard’ comparison protocol, we preclinically tested the comparative venom-neutralising efficacy of four antivenoms available in Kenya with two antivenoms of clinically-proven efficacy. To explain the variant efficacies of these antivenoms we tested the IgG-venom binding characteristics of each antivenom using in vitro IgG titre, avidity and venom-protein specificity assays. We also measured the IgG concentration of each antivenom. Findings None of the six antivenoms are preclinically effective, at the doses tested, against all of the most medically important snakes of the region. The very limited snake polyspecific efficacy of two locally available antivenoms is of concern. In vitro assays of the abilities of ‘test’ antivenom IgGs to bind venom proteins were not substantially different from that of the ‘gold standard’ antivenoms. The least effective antivenoms had the lowest IgG content/vial. Conclusions Manufacture-stated preclinical efficacy statements guide decision making by physicians and antivenom purchasers in sub-Saharan Africa. This is because of the lack of both clinical data on the efficacy of most of the many antivenoms used to treat patients and independent preclinical assessment. Our preclinical efficacy assessment of antivenoms available in Kenya identifies important limitations for two of the most commonly-used antivenoms, and that no antivenom is preclinically effective against all the regionally important snakes. The potential implication to snakebite treatment is of serious concern in Kenya and elsewhere in sub-Saharan Africa, and underscores the dilemma physicians face, the need for clinical data on antivenom efficacy and the medical and societal value of establishing independent preclinical antivenom-efficacy testing facilities throughout the continent., Author summary Snakebite is one of the most under-researched, under-resourced high morbidty/high mortality NTDs, as reflected by the fact that many of the antivenoms used to treat snakebite victims in sub-Saharan Africa are of uncertain and untested efficacy. This Kenya case study is the first examination of the preclinical efficacy of all available antivenoms to neutralize the venom toxic effects of the most medically important snakes in any region of sub-Saharan Africa. Our results identify serious preclinical efficacy limitations in two of the most commonly used antivenoms, that no single antivenom is effective against all regionally important snakes and that the least effective antivenoms had the lowest IgG concentrations. It is our aim that Ministry of Health medicine-supply regulators can use this data as evidence to demand more detailed efficacy evidence from manufacturers, and to justify the establishment of national/regional preclinical testing facilities. We hope this publication will also alert physicians treating African snakebite victims to check the efficacy of antivenom in their pharmacies. We have carefully qualified the extent and limitation of the results and of our interpretation of the clinical implications thereof.

Background Efforts in search of lasting malaria vaccine have led to the development of transgenic rodent malaria parasites. As a result, wild type Plasmodium berghei ANKA (WTPbA) has recently been transformed to express mouse interferon gamma (mIFN-γ). The immunomodulatory effect of this transgenic parasite on WTPbA infection has been demonstrated. However, the protective immune responses after repeated immunization with soluble lysate of this parasite has not been investigated. Methods Soluble lysate of transgenic PbA (TPbA) was prepared and concentration of IFN-γ in lysate determined by ELISA. Four groups of 20 BALB/c mice each (two treatment groups and two control groups) were setup. Treatment Groups 1 and 2 were primed (at day 0) with lysate of TPbA containing 75 pg/ml IFN-γ and live TPbA parasites respectively. Infection in Group 2 mice was cured with Coartem™ at 450 mg/kg for 3 days. At day 14 post-priming, both groups were boosted twice at day 14 and day 28 with lysate of TPbA containing 75 pg/ml IFN-γ and 35 pg/ml IFN-γ respectively. Blood and spleen samples were collected at day 0, day 14, day 21 and day 28 for preparation of serum and cell cultures respectively. Serum IgG and cytokines (TNF-α and IFN-γ) levels in culture supernatant were measred by ELISA.Survivorship and parasitemia were daily monitored for 21 days. Data were statistically analyzed using ANOVA student’s t test. A p value of

Background Drug resistance against first-line antimalarials warrants search for new lead compounds and repurposing of drugs such as methotrexate. Animal models are required for preclinical drug development before clinical testing. This study aimed to develop a preclinical drug development system in baboons infected with Plasmodium knowlesi. Methods Protocols for drug administration, pharmacokinetics, clinical chemistry and haematology were developed in the baboon model. Baboons were infected with P. knowlesi and methotrexate administered orally for 5 days. Clinical signs, parasitaemia, gross and histopathology examinations were conducted to determine effect of methotrexate in baboons. Results No major clinical chemistry, haematology and pathological changes attributable to methotrexate were observed. Parasitaemia suppression of 77.67% was achieved at a methotrexate dose of 3.0 mg/kg. Conclusions A protocol for preclinical drug development in the baboon was optimized. Methotrexate suppressed P. knowlesi malaria in baboons. These findings warrant further characterization of methotrexate for use in combination therapy.

Malaria and schistosomiasis coinfections are common, and chronic schistosomiasis has been implicated in affecting the severity of acute malaria. However, whether it enhances or attenuates malaria has been controversial due the lack of appropriately controlled human studies and relevant animal models. To examine this interaction, we conducted a randomized controlled study using the baboon ( Papio anubis ) to analyze the effect of chronic schistosomiasis on severe malaria. Two groups of baboons ( n = 8 each) and a schistosomiasis control group ( n = 3) were infected with 500 Schistosoma mansoni cercariae. At 14 and 15 weeks postinfection, one group was given praziquantel to treat schistosomiasis infection. Four weeks later, the two groups plus a new malaria control group ( n = 8) were intravenously inoculated with 10 5 Plasmodium knowlesi parasites and monitored daily for development of severe malaria. A total of 81% of baboons exposed to chronic S. mansoni infection with or without praziquantel treatment survived malaria, compared to only 25% of animals infected with P. knowlesi only ( P = 0.01). Schistosome-infected animals also had significantly lower parasite burdens ( P = 0.004) than the baboons in the P. knowlesi -only group and were protected from severe anemia. Coinfection was associated with increased spontaneous production of interleukin-6 (IL-6), suggesting an enhanced innate immune response, whereas animals infected with P. knowlesi alone failed to develop mitogen-driven tumor necrosis factor alpha and IL-10, indicating the inability to generate adequate protective and balancing immunoregulatory responses. These results indicate that chronic S. mansoni attenuates the severity of P. knowlesi coinfection in baboons by mechanisms that may enhance innate immunity to malaria.

Red cell invasion by Plasmodium merozoites involves multiple steps such as attachment, apical reorientation, junction formation and entry into a parasitophorous vacuole. These steps are mediated by specific molecular interactions. P. vivax and the simian parasite P. knowlesi require interaction with the Duffy blood group antigen to invade human erythrocytes. P. vivax and P. knowlesi Duffy binding proteins (PvDBP and PkDBP), which bind the Duffy antigen during invasion, share regions of sequence homology and belong to a family of erythrocyte binding proteins (EBPs). By deletion of the gene that encodes PkDBP, we demonstrate that interaction of PkDBP with the Duffy antigen is absolutely necessary for invasion of human erythrocytes by P. knowlesi. Electron microscopy studies reveal that PkDBP knockout parasites are unable to form a junction with human erythrocytes. The interaction of PkDBP with the Duffy antigen is thus necessary for the critical step of junction formation during invasion. These studies provide support for development of intervention strategies that target EBPs to inhibit junction formation and block erythrocyte invasion by malaria parasites.

Experimental systems that model some of the complex interactions between parasite and host can be extremely valuable in identifying and developing new prophylactics and therapeutics against human diseases. Because primates have similar immune systems to humans, we have characterized a baboon model for understanding host response to Plasmodium knowlesi. Ten intact olive baboons (Papio anubis) of either sex were experimentally infected with P. knowlesi H strain erythrocytic parasites. The infection in these baboons was either acute or chronic. Animals with acute infection developed multiple system organ dysfunction and cerebral involvement. In chronically infected animals, only the spleen was moderately enlarged. The P. knowlesi parasitemia profile in baboons and rhesus monkeys was comparable. However, some clinical symptoms of the baboons and P. falciparum-infected humans were similar. These studies demonstrate for the first time that P. anubis is a suitable host for P. knowlesi for studying clinical symptoms and pathology.

Recombinant pathogenic microorganisms expressing host cytokines such as gamma interferon (IFN-γ) have been shown to modulate immune responses, leading to enhanced protection (15-17, 19, 35, 43, 47). Vaccinia virus and simian immunodeficiency viruses expressing a range of host cytokines were attenuated in vivo, leading to enhanced immune responses (15-17), and Leishmania major expressing host IFN-γ was significantly attenuated in nude mice (47). These data indicate that in vivo expression of host cytokines by pathogens can manipulate the host-pathogen interaction and generate protective host responses. Thus far, expression of host cytokines by malaria parasites has not been examined. The development of transfection technology for malaria parasites (18, 49, 51, 54) now enables expression of recombinant host proteins, such as cytokines in Plasmodium. IFN-γ is one of the central effector cytokines in host response to malaria infection, especially during the liver stage (14, 21, 33, 38-40) and hence is attractive for expression in malaria parasites. In vitro and in vivo studies in rodent models of malaria have demonstrated that IFN-γ plays a central role in protection against malaria liver-stage infection, possibly by inducing the infected hepatocyte to produce nitric oxide that kills parasites (31, 33). In clinical vaccination studies with an attenuated sporozoite vaccine (reviewed in reference 32), vaccinated humans were protected from subsequent infection through IFN-γ-dependent responses. In separate studies in mice and monkeys, sterile protection was achieved through IFN-γ-dependent responses after exogenous treatment with interleukin-12 (IL-12) (21, 39). Studies using rodent and human malaria models have demonstrated that IFN-γ also plays a role in protection against malaria blood stages when either endogenously produced (11, 20, 28, 44, 45, 55) or exogenously administered (2, 8, 9, 41). Although cytokines have been shown to mediate protection against malaria infection after exogenous delivery (8, 21, 39, 41), systemically delivered cytokines are short-lived and require repetitive administration (often in large doses that could be toxic to the host) (6, 9, 22), and only a small portion reaches the site of infection (6, 26). Alternatively, cytokine expression by the pathogen itself will ensure that the cytokine is released where its activity is required, as long as the infection persists and in proportion to the level of infection. In this report, Plasmodium knowlesi, a natural malaria parasite of macaque monkeys (5) and an experimental system for human malaria, was transfected in vitro to express Macaca mulatta IFN-γ. In vitro expression and bioactivity of P. knowlesi-expressed rhesus monkey IFN-γ (rhIFN-γ) was characterized, showing for the first time that malaria parasites can produce a bioactive recombinant host cytokine.

Transfection technology for malaria parasites provides a valuable tool for analyzing gene function and correlating genotype with phenotype. Transfection models are even more valuable when appropriate animal models are available in addition to complete in vitro systems to be able to fully analyze parasite-host interactions. Here we describe the development of such a model by using the nonhuman primate malariaPlasmodium knowlesi. Blood-stage parasites were adapted to long-term in vitro culture. In vitro-adapted parasites could readapt to in vivo growth and regain wild-type characteristics after a single passage through an intact rhesus monkey.P. knowlesiparasites, either in vitro adapted or in vivo derived, were successfully transfected to generate circumsporozoite protein (CSP) knockout parasites by double-crossover mechanisms. In vitro-transfected and cloned CSP knockout parasites were derived in a time span of only 18 days. Microscopic evaluation of developing oocysts from mosquitoes that had fed on CSP knockout parasites confirmed the impairment of sporozoite formation observed inP. bergheiCSP knockout parasites. TheP. knowlesimodel currently is the only malaria system that combines rapid and precise double-crossover genetic manipulation procedures with complete in vitro as well as in vivo possibilities. This allows for full analysis ofP. knowlesigenotype-phenotype relationships and host-parasite interactions in a system closely related to humans.

Plasmodium falciparum Pfs25 antigen, expressed on the surface of zygotes and ookinetes, is one of the leading targets for the development of a malaria transmission-blocking vaccine (TBV). Our laboratory has been evaluating DNA plasmid based Pfs25 vaccine in mice and non-human primates. Previously, we established that in vivo electroporation (EP) delivery is an effective method to improve the immunogenicity of DNA vaccine encoding Pfs25 in mice. In order to optimize the in vivo EP procedure and test for its efficacy in more clinically relevant larger animal models, we employed in vivo EP to evaluate the immune response and protective efficacy of Pfs25 encoding DNA vaccine in nonhuman primates (Olive baboons, Papio anubis). The results showed that at a dose of 2.5 mg DNA vaccine, antibody responses were significantly enhanced with EP as compared to without EP resulting in effective transmission blocking efficiency. Similar immunogenicity enhancing effect of EP was also observed with lower doses (0.5 mg and 1 mg) of DNA plasmids. Further, final boosting with a single dose of recombinant Pfs25 protein resulted in dramatically enhanced antibody titers and significantly increased functional transmission blocking efficiency. Our study suggests priming with DNA vaccine via EP along with protein boost regimen as an effective method to elicit potent immunogenicity of malaria DNA vaccines in nonhuman primates and provides the basis for further evaluation in human volunteers.

Malaria is a major and growing threat to economic development and public health in developing countries. There are about 2.7 million malaria deaths annually. Plasmodium knowlesi, the fifth human malaria parasite, is an attractive model for malaria research and is also phylogenetically close to human malaria parasite P. vivax . It shares many vaccine candidate molecules with P. vivax . This study was carried out to determine immunological profiles mounted by Olive baboons during experimental infection with P. knowlesi H strain. Six Olive baboons ( Papio Anubis ) were infected with 1×10 6 P . knowlesi blood stage parasites. The infected baboons developed either severe (acute) or mild (chronic) infection. High IgM titres were observed during primary infection in the baboons. Anti-IgG antibodies were raised after two weeks of chronic infection. Circulating IFNg from serum rose fifty fold in acutely infected animals during the first two weeks post infection compared to a tenfold increase in chronically infected baboons. Recall proliferative responses were two fold higher in chronically infected animals by day 14 post infection. The highest stimulation index (10.06 + 2.74) was observed in chronic animals at day 42 post infection. These results demonstrated that baboons infected with P. knowlesi mount an immune response that is characterized by antibody and cytokine responses involving IgG, IgM and IFNr. These studies are important in validation of the P. knowlesi - baboon model for malaria drug and vaccine development.

Babesia microti-like parasites have been reported to infect captive non-human primates (NHPs). However, studies on the prevalence of Babesia spp. in free-ranging NHPs are lacking. This investigation aimed at determining the prevalence of B. microti in wild-caught Kenyan NHPs. In total, 125 animals were studied, including 65 olive baboons (Papio cynocephalus anubis) and 60 African green monkeys ([AGMs] Chlorocebus aethiops). Nested polymerase chain reaction targeting Babesia β-tubulin genes was used to diagnose infection prevalence. Results indicated a prevalence of 22% (27/125) B. microti infection in free-ranging NHPs in Kenya. There was no statistically significant difference in B. microti infection prevalence between baboons and AGMs or male and female animals. This is the first report of the presence and prevalence of B. microti in free-ranging Kenyan NHPs.

Introduction: Infections from extended spectrum beta lactamases (ESBLs) producing enterobacteriaceae are increasingly being reported in the community setting. These infections are often multidrug resistant, with clinical and epidemiological implications, and necessitate surveillance measures based on local data. In the present study ESBLs genotypes were correlated with susceptibility to cephalosporins among ESBL-producing Escherichia coli and Klebsiella pneumoniae isolates acquired in the community. Methodology: We investigated 28 E. coli and 24 K. pneumoniae isolates by PCR for the presence of bla SHV , bla CTX-M , and bla TEM . Minimum inhibitory concentration (MIC) for cephalosporins was determined by use of E-tests. Results: bla CTX-M was detected in 46 (88.5%), bla SHV in 13 (25%) and bla TEM in18 (34.6%) of the isolates. Nineteen (36.5%) isolates had more than one genotype detected. Urine specimens provided most of the ESBL-producing isolates (71%) followed by respiratory specimens (11%). MIC 50 for cefotaxime, ceftazidime, and ceftriaxone were at 60μg/ml, 13μg/ml, and 139μg/ml, respectively. There was a statistically significant association (p-value = 0.017) between bla SHV and resistance to ceftazidime. Though other associations could be seen among the genotypes and susceptibility profiles of the three drugs, they were not statistically significant. Twenty-four (52.2%) of the bla CTX-M isolates were sensitive and nine (19.6%) resistant to ceftazidime. For cefotaxime, 29 (63%) of bla CTX-M isolates were resistant and two (4.3%) were sensitive. Conclusion: The predominant ESBL genotype in the local community-acquired infections is bla CTX-M , most of which involved the urinary tract. ESBL genes elevated MICs for the cephalosporins, but only bla SHV could predict resistance to ceftazidime.

Tunga penetrans are fleas that cause tungiasis, a condition characterized by high transmission rate due to poor housing conditions, social neglect and inadequate health care in economically disadvantaged communities in developing countries. This study therefore aimed at characterizing jiggers antigens to identify immunodominant ones to help understand immunological behavior of the parasite that would otherwise be important in future control of the parasite. Samples were gravid fleas and blood samples from infested individuals in Kahuro and Murang’a East district in Murang’a County. Freeze and thaw was used to extract soluble proteins from the fleas. Ouchterlony Double immunodiffusion was used to assess antigen-antibody reactions between extracted soluble protein and the serum from immunized rats, Rattus norvegicus prior to analysis of human sera. These results were comparable to results of immunoelectrphoresis. Jigger protein isolates were analyzed in Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis technique (SDS—PAGE), against Pharmacia standard protein markers. Further analysis of jigger antigens against pooled human sera from infested victims in Western blot revealed three immunodominant antigens. Using simple regression analysis molecular weights of the three immunodominant antigens were estimated as 51.795, 23.395 and 15.38 kDa respectively. These results are important since they would help understand immunological behavior of the parasites. This would help to create basis for designing and improving approaches against jiggers such as development of immune prophylaxis to complement social science approaches that is mainly concerned with maintenance of high standards of hygiene., Author Summary Tungiasis is the condition caused by jigger infestation. It is common in tropical countries where it has caused high morbidity among economically disadvantaged communities. It is a neglected tropical disease to an extent that enough research has not been done in this area. More over the infested hardly seek medical treatment due to stigma. Consequently, the pathological and immunological characteristic of this ectoparasite are not well understood. Hence effective therapy is not yet found. Some traditional methods to combat tungiasis such as extraction of embedded fleas could lead to spread of HIV through sharing of contaminated sharp objects especially in schools. This call for more appropriate strategies to fight the menace, including the ones based on immunological characteristic of the parasite. This study therefore is an initial deliberate endeavor to achieve this goal. Result of this study shows that T. penetrans isolates possess three important immuno-dominant antigens. These antigens results in immunological responses experienced by the victims such as inflammation. Further analysis of these results could give in-depth information on immunological characteristics of the parasite and its pathological effects on victims. This could make fertile grounds for designing of effective and preventive strategies against the parasite or its pathological effects.

Red cell invasion by Plasmodium merozoites involves multiple steps such as attachment, apical reorientation, junction formation and entry into a parasitophorous vacuole. These steps are mediated by specific molecular interactions. P. vivax and the simian parasite P. knowlesi require interaction with the Duffy blood group antigen to invade human erythrocytes. P. vivax and P. knowlesi Duffy binding proteins (PvDBP and PkDBP), which bind the Duffy antigen during invasion, share regions of sequence homology and belong to a family of erythrocyte binding proteins (EBPs). By deletion of the gene that encodes PkDBP, we demonstrate that interaction of PkDBP with the Duffy antigen is absolutely necessary for invasion of human erythrocytes by P. knowlesi. Electron microscopy studies reveal that PkDBP knockout parasites are unable to form a junction with human erythrocytes. The interaction of PkDBP with the Duffy antigen is thus necessary for the critical step of junction formation during invasion. These studies provide support for development of intervention strategies that target EBPs to inhibit junction formation and block erythrocyte invasion by malaria parasites.

There are relatively few monoclonal antibodies (mAb) that have been characterized for their applicability in studies on the immune system of various nonhuman primates. In the present study, we identified a large number of mAb that can be used in future immunological studies in three different nonhuman primates, i.e., chimpanzees, rhesus macaques, and squirrel monkeys. The reactivity of 161 anti-human mAb to T-cell antigens and cytokine receptors were tested on peripheral blood mononuclear cells (PBMC) from the three primate species by flow cytometric analysis. A total of 105 (65%), 73 (45%), and 68 (42%) antibodies reacted with PBMC from chimpanzees, rhesus macaques, and squirrel monkeys, respectively. Out of the 161 mAb, 38 reacted with all three species and 112 reacted with one or two of the species. No specific reaction was observed with mAb to receptors to GM-CSF, 4-1BB, FLT3, FLX2, common beta-chain, IL-1 (type I receptor), and IL-8.

Background Placental malaria (PM) causes adverse pregnancy outcomes in the mother and her foetus. It is difficult to study PM directly in humans due to ethical challenges. This study set out to bridge this gap by determining the outcome of PM in non-immune baboons in order to develop a non-human primate model for the disease. Methods Ten pregnant baboons were acquired late in their third trimester (day 150) and randomly grouped as seven infected and three non-infected. Another group of four nulligravidae (non-pregnant) infected was also included in the analysis of clinical outcome. Malaria infection was intravenously initiated by Plasmodium knowlesi blood-stage parasites through the femoral vein on 160th day of gestation (for pregnant baboons). Peripheral smear, placental smear, haematological samples, and histological samples were collected during the study period. Median values of clinical and haematological changes were analysed using Kruskal-Wallis and Dunn’s Multiple Comparison Test. Parasitaemia profiles were analysed using Mann Whitney U test. A Spearman’s rank correlation was run to determine the relationship between the different variables of severity scores. Probability values of P