Efficient infection of non-human primates with purified, cryopreserved Plasmodium knowlesi sporozoites

Background

Plasmodium falciparum (Pf) sporozoite (SPZ) vaccines are the only candidate malaria vaccines that induce > 90% vaccine efficacy (VE) against controlled human malaria infection and the only malaria vaccines to have achieved reproducible VE against malaria in adults in Africa. The goal is to increase the impact and reduce the cost of PfSPZ vaccines by optimizing vaccine potency and manufacturing, which will benefit from identification of immunological responses contributing to protection in humans. Currently, there is no authentic animal challenge model for assessing P. falciparum malaria VE. Alternatively, Plasmodium knowlesi (Pk), which infects humans and non-human primates (NHPs) in nature, can be used to experimentally infect rhesus macaques (Macaca mulatta) to assess VE.

Methods

Sanaria has, therefore, produced purified, vialed, cryopreserved PkSPZ and conducted challenge studies in several naïve NHP cohorts. In the first cohort, groups of three rhesus macaques each received doses of 5 × 10², 2.5 × 10³, 1.25 × 10⁴ and 2.5 × 10⁴ PkSPZ administered by direct venous inoculation. The infectivity of 1.5 × 10³ PkSPZ cryopreserved with an altered method and of 1.5 × 10³ PkSPZ cryopreserved for four years was tested in a second and third cohort of rhesus NHPs. The lastly, three pig-tailed macaques (Macaca nemestrina), a natural P. knowlesi host, were challenged with 2.5 × 10³ PkSPZ cryopreserved six years earlier.

Results

In the first cohort, all 12 animals developed P. knowlesi parasitaemia by thick blood smear, and the time to positivity (prepatent period) followed a non-linear 4-parameter logistic sigmoidal model with a median of 11, 10, 8, and 7 days, respectively (r² = 1). PkSPZ cryopreserved using a modified rapid-scalable method infected rhesus with a pre-patent period of 10 days, as did PkSPZ cryopreserved four years prior to infection, similar to the control group. Cryopreserved PkSPZ infected pig-tailed macaques with median time to positivity by thin smear, of 11 days.

Conclusion

This study establishes the capacity to consistently infect NHPs with purified, vialed, cryopreserved PkSPZ, providing a foundation for future studies to probe protective immunological mechanisms elicited by PfSPZ vaccines that cannot be established in humans.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-022-04261-z.

Use of Magnetic Resonance Imaging in the Evaluation ofAcute Cholecystitis in Emergency Setting

Background Acute cholecystitis is one of the commonest surgical disease. The rapid diagnosis at its early stage is one of the crucial factor in patient care and management. Objective To evaluate the role of magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography (MRCP) in the diagnosis or exclusion of acute cholecystitis, coexisting choledocholithiasis, and acute pancreatitis in emergency setting. Method This study was conducted in the department of radiodiagnosis B and C teaching hospital, Birtamod, Nepal from July 2016 to November 2019. Patients, clinically diagnosed as acute cholecystitis or biliary condition with positive Murphy's sign with or without jaundice and deranged Liver Function Test, raised Leucocyte counts were evaluated by Magnetic Resonance imaging. The sensitivity, specificity, Positive Productive Value (PPV), Negative Productive Value (NPV) were calculated for the diagnosis of acute cholecystitis. Data was entered and analysed by using SPSS version 20. Result There were 40 patients included in our study. Among them 27 (67.5%) were females and 13 (32.5%) male. The age of the patients ranged from 16 years to 79 years, mean age 49.4 years. Majority of the patients were in the age group of 40-60 years (57.5%). The overall sensitivity, specificity, Positive Productive Value and Negative Productive Value of Magnetic Resonance imaging diagnosis of acute cholecystitis were 100%, 66.6%, 94.4% and 100% respectively. Acute cholecystitis associated with gall stone disease were common and found in 72.5% cases, with sensitivity 96.5%, specificity 27.7%, Positive Productive Value 77.7% and Negative Productive Value 75.0%. Conclusion Magnetic resonance imaging (MRI)/Magnetic resonance cholangiopancreatography (MRCP) is an excellent tool for the evaluation of biliary pathology and can be used for the preoperative evaluation of acute cholecystitis at the emergency setting.

CCR6 expression reduces mouse survival upon malarial challenge with Plasmodium berghei NK65 strain

BACKGROUND

It has been demonstrated that proteins expressed by liver-stage Plasmodium parasites can inhibit the translocation of transcription factors to the nucleus of different cells. This process would hinder the expression of immune genes, such as the CCL20 chemokine.

OBJECTIVE

Since CCR6 is the only cognate receptor for CCL20, we investigated the importance of this chemokine-receptor axis against rodent malaria.

METHODS

CCR6-deficient (KO) and wild-type (WT) C57BL/6 mice were challenged with Plasmodium berghei (Pb) NK65 sporozoites or infected red blood cells (iRBCs). Liver parasitic cDNA, parasitemia and serum cytokine concentrations were respectively evaluated through reverse transcription-polymerase chain reaction (RT-PCR), staining thin-blood smears with Giemsa solution, and enzyme-linked immunosorbent assay (ELISA).

FINDINGS

Although the sporozoite challenges yielded similar liver parasitic cDNA and parasitemia, KO mice presented a prolonged survival than WT mice. After iRBC challenges, KO mice kept displaying higher survival rates as well as a decreased IL-12 p70 concentration in the serum than WT mice.

CONCLUSION

Our data suggest that malaria triggered by PbNK65 liver- or blood-stage forms elicit a pro-inflammatory environment that culminates with a decreased survival of infected C57BL/6 mice.

Release of extracellular vesicle miR-494-3p by ARPE-19 cells with impaired mitochondria

BACKGROUND

Mitochondrial function in retinal pigmented epithelial (RPE) cells and extracellular vesicle (EV) formation/release are related through the lysosomal and exocytotic pathways that process and eliminate intracellular material, including mitochondrial fragments. We propose that RPE cells with impaired mitochondria will release EVs containing mitochondrial miRNAs that reflect the diminished capacity of mitochondria within these cells.

METHODS

We screened ARPE-19 cells for miRNAs that localize to the mitochondria, exhibit biological activity, and are present in EVs released by both untreated cells and cells treated with rotenone to induce mitochondrial injury. EVs were characterized by vesicle size, size distribution, presence of EV biomarkers: CD81, CD63, and syntenin-1, miRNA cargo, and number concentration of EVs released per cell.

RESULTS

We found that miR-494-3p was enriched in ARPE-19 mitochondria. Knockdown of miR-494-3p in ARPE-19 cells decreased ATP production and mitochondrial membrane potential in a dose-dependent manner, and decreased basal oxygen consumption rate and maximal respiratory capacity. Increased number of EVs released per cell and elevated levels of miR-494-3p in EVs released from ARPE-19 cells treated with rotenone were also measured.

CONCLUSIONS

ARPE-19 mitochondrial function is regulated by miR-494-3p. Elevated levels of miR-494-3p in EVs released by ARPE-19 cells indicate diminished capacity of the mitochondria within these cells.

GENERAL SIGNIFICANCE

EV miR-494-3p is a potential biomarker for RPE mitochondrial dysfunction, which plays a central role in non-neovascular age-related macular degeneration, and may be a diagnostic biomarker for monitoring the spread of degeneration to neighboring RPE cells in the retina.

Abstract P2-12-05: Real-time, intraoperative detection of residual breast cancer in lumpectomy cavity margins using the LUM imaging system: Results of a feasibility study

Background: Obtaining tumor-free margins is critical for local control in breast conserving surgery. Currently, 20-40% of lumpectomy patients have positive margins that require surgical re-excision. We assessed the LUM Imaging System for real-time, intraoperative detection of residual tumor in breast cancer patients. The LUM System has the particular advantage of assessing in vivo lumpectomy cavity walls rather than excised specimens, to enable more accurate excision of residual tumor.

Methods: Lumpectomy cavity walls of patients undergoing lumpectomy for invasive breast cancer or ductal carcinoma in situ (DCIS), were assessed intraoperatively using the LUM Imaging System (Lumicell Inc., Wellesley MA). LUM015, a cathepsin-activatable fluorescent agent, was given IV 4±2 hrs prior to surgery. Areas of fluorescence generated at potential sites of residual tumor in lumpectomy cavities were evaluated with a sterile hand-held device, displayed on a monitor, excised and correlated with histopathology.

Results: In vivo lumpectomy cavities were imaged with the LUM Imaging System in 60 breast cancer patients. 5 were imaged without dye. 55 received LUM015 dye preoperatively and were scanned intraoperatively. Median age was 60 years (range 44-79). Mean tumor size was 1.2cm (0.06-3.5cm) with 71% invasive cancers, 29% DCIS. The test set included 569 cavity margin surfaces assessed intraoperatively and excised. Image acquisition for each margin took approximately 1 second. The LUM Imaging System showed 100% sensitivity and 73% specificity for detection of tumor <2mm from the margin. Invasive ductal cancer (IDC), invasive lobular cancer (ILC) and areas of DCIS 1mm in size could be identified. 8 patients had positive margins on standard histopathology analysis (Table). The LUM System correctly identified all positive margins identified by standard histopathology and correctly predicted negative re-excisions in 2 of 8 patients. There were no serious adverse events. 1 patient had extravasation of LUM015 at her injection site with temporary blue skin staining but no other complication.

Conclusions: The LUM Imaging System allows real-time identification of residual tumor in the lumpectomy cavity of breast cancer patients. No sites of residual tumor were missed. Additional studies are underway to optimize this approach for reducing positive margins and second surgeries in breast cancer patients.

Table: Margin results in 8 patients with positive margins on initial lumpectomy specimenPositive lumpectomy margin histopathologyLUM cavity wall result (+/- for tumor)Tumor found at re-excisionDCIS++DCIS+-DCIS++IDC++ (Mastectomy)ILC++ (Mastectomy)DCIS+-IDC--DCIS--

Citation Format: Lanahan CR, Gadd MA, Specht MC, Ferrer J, Tang R, Rai U, Merrill AL, Biernacka A, Brachtel E, Smith BL. Real-time, intraoperative detection of residual breast cancer in lumpectomy cavity margins using the LUM imaging system: Results of a feasibility study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-12-05.

A potent malaria vaccine based on adenovirus with dual modifications at Hexon and pVII

Adenovirus (Ad) is thought to be one of the most promising platforms for a malaria vaccine targeted against its liver stages, because of its ability to induce a strong T-cell response against a transgene. However, a further improvement of this platform is needed in order to elicit another arm of the immunity, i.e. humoral response, against malaria. In order to augment immunogenicity and protective efficacy of Ad-based malaria vaccine, we inserted B-cell, as well as CD4+ T-cell, epitopes of Plasmodium falciparum circumsporozoite protein (PfCSP) into the capsid protein, Hexon, and the core protein, VII (pVII), of Ad, respectively, in addition to the PfCSP transgene. Insertion of PfCSP-derived B cell epitope to Hexon significantly enhanced the epitope-specific antibody response compared to AdPfCSP, an Ad vaccine expressing only PfCSP transgene. PfCSP-derived CD4+ T-cell epitope insertion into pVII augmented not only PfCSP-specific CD4+ T-cell response but also anti-PfCSP antibody response. Finally, mice immunized with AdPfCSP having both Hexon and pVII modifications were more protected than AdPfCSP or Hexon-modified AdPfCSP against challenge with transgenic rodent malaria parasites expressing the PfCSP. Overall, this study has demonstrated that Hexon and pVII-modified AdPfCSP vaccine is a promising malaria vaccine which induces strong PfCSP-specific humoral, CD4+ T-cell, and CD8+ T-cell responses and protects against infection with transgenic malaria parasites expressing the PfCSP.

Prognostic value of peripheral leukocyte counts and plasma glucose in intracerebral haemorrhage

INTRODUCTION

The value of routine blood markers as prognostic indicators is increasingly established in acute ischaemic stroke. The relationship is less well defined in haemorrhagic stroke. In this study, we examined routine admission blood markers and applied a logistic regression model to predict outcome in haemorrhagic stroke.

METHOD

A retrospective study was performed between September 2009-2011 in a general admission stroke unit in the UK. 1400 patients were admitted with stroke during this period, of which 117 were haemorrhagic. Admission systolic and diastolic blood pressure, venous blood samples and pre- and post-morbid (i.e. at discharge or death) modified Rankin scores were also recorded. Patients were controlled for age, sex, smoking status, hypertension status and co-morbidities (using Charleson Comorbidity Index scores). Logistic regression models were generated using SPSS.

RESULTS

113 patients were analysed (58 male/55 female). Lower admission blood glucose (p=0.009), lower total leukocyte count (p=0.001) and lower neutrophil count (p=0.021) were found to be significantly associated with survival vs. death. 90 patients with complete glucose, leukocyte count, sex (forced) and pre-morbid Rankin score (forced) data were entered into a logistic regression model. This predicted correct group membership (survived/deceased) in 72.2% of cases (83.9% survivors/52.9% deceased correctly predicted). In females with normal leukocyte count and glucose, survival was predicted with 68% accuracy.

CONCLUSION

These results suggest that a logistic regression model using low admission glucose and low total leukocyte count may be markers of better prognosis in acute haemorrhagic stroke with a differential effect between sexes.

Nucleolar asymmetry and the importance of septin integrity upon cell cycle arrest

Cell cycle arrest can be imposed by inactivating the anaphase promoting complex (APC). In S. cerevisiae this arrest has been reported to stabilize a metaphase-like intermediate in which the nuclear envelope spans the bud neck, while chromatin repeatedly translocates between the mother and bud domains. The present investigation was undertaken to learn how other features of nuclear organization are affected upon depletion of the APC activator, Cdc20. We observe that the spindle pole bodies and the spindle repeatedly translocate across the narrow orifice at the level of the neck. Nevertheless, we find that the nucleolus (organized around rDNA repeats on the long right arm of chromosome XII) remains in the mother domain, marking the polarity of the nucleus. Accordingly, chromosome XII is polarized: TelXIIR remains in the mother domain and its centromere is predominantly located in the bud domain. In order to learn why the nucleolus remains in the mother domain, we studied the impact of inhibiting rRNA synthesis in arrested cells. We observed that this fragments the nucleolus and that these fragments entered the bud domain. Taken together with earlier observations, the restriction of the nucleolus to the mother domain therefore can be attributed to its massive structure. We also observed that inactivation of septins allowed arrested cells to complete the cell cycle, that the alternative APC activator, Cdh1, was required for completion of the cell cycle and that induction of Cdh1 itself caused arrested cells to progress to the end of the cell cycle.

Abstract P4-01-05: In vivo, intraoperative margin detection utilizing the Lumicell margin assessment system

This abstract was withdrawn by the authors.

A sufficient role of MHC class I molecules on hepatocytes in anti-plasmodial activity of CD8 (+) T cells in vivo

Although CD8⁺ T cells are shown to mediate the protective immunity against the liver stages of malaria parasites in mice, whether the direct presentation of malaria antigen by major histocompatibility complex (MHC) class I molecules expressed on the liver of infected host is required for anti-plasmodial activity of CD8⁺ T cells is still unknown. Presently, there is only one CD8⁺ epitope, SYVPSAEQI, derived from the circumsporozoite protein of Plasmodium yoelii (PyCS), that mediates anti-malarial protection and is presented in the context of a K^d molecule. Therefore, to investigate the mode of anti-plasmodial activity of CD8+ T cells, we have previously generated C57BL/6 transgenic (Tg) mice, in which a K^d molecule is expressed only on hepatocyte (Alb-K^d) or dendritic cell (DC; CD11c-K^d), by using albumin promoter or CD11c promoter, respectively. We have also generated MHC-I-K^d Tg mice, which express the K^d molecule under the MHC class I (MHC-I) promoter, as a positive control. From splenocytes collected from CD11c-K^d Tg mice immunized with a synthetic peptide, SYVPSAEQI, which corresponds to the CD8⁺ T-cell epitope of PyCS, emulsified in incomplete Freund’s adjuvant , a PyCS-specific CD8⁺ T-cell line was generated. This PyCS-specific CD8⁺T-cell line was then adoptively transferred into a cohort of either MHC-K^d Tg or Alb-K^d Tg mice listed above, as well as wild-type C57BL/6 mice. Then both transferred and non-transferred mice were challenged with live malaria parasites. We found that the adoptive transfer of a PyCS-specific CD8⁺ T-cell line resulted in a significant inhibition of the parasite burden in the liver of Alb-K^d Tg, as well as MHC-I-K^d Tg mice, but not of C57BL/6 mice. These results indicate that the K^d molecule expressed by hepatocytes is sufficient in mediating the anti-plasmodial activity of PyCS-specific CD8⁺ T cells in vivo.

Identification of non-CSP antigens bearing CD8 epitopes in mice immunized with irradiated sporozoites

Immunization of BALB/c mice with irradiated sporozoites (IrSp) of Plasmodium yoelii can lead to sterile immunity. The circumsporozoite protein (CSP) plays a dominant role in protection. Nevertheless after hyper-immunization with IrSp, complete protection is obtained in CSP-transgenic BALB/c mice that are T-cell tolerant to the CSP and cannot produce antibodies [CSP-Tg/JhT(-/-)]. This protection is mediated exclusively by CD8(+) T cells [1]. To identify the non-CSP protective T cell antigens, we studied the properties of 34 P. yoelii sporozoite antigens that are predicted to be secreted and to contain strong Kd-restricted CD8(+) T cell epitopes. The synthetic peptides corresponding to the epitopes were used to screen for the presence of peptide-specific CD8(+) T cells secreting interferon-γ (IFN-γ) in splenocytes from CSP-Tg/JhT(-/-) BALB/c mice hyper immunized with IrSp. However, the numbers of IFN-γ-secreting splenocytes specific for the non-CSP antigen-derived peptides were 20-100 times lower than those specific for the CSP-specific peptide. When mice were immunized with recombinant adenoviruses expressing selected non-CSP antigens, the animals were not protected against challenge with P. yoelii sporozoites although large numbers of CD8(+) specific T cells were generated.

Replacing adenoviral vector HVR1 with a malaria B cell epitope improves immunogenicity and circumvents preexisting immunity to adenovirus in mice

Although adenovirus (Ad) has been regarded as an excellent vaccine vector, there are 2 major drawbacks to using this platform: (a) Ad-based vaccines induce a relatively weak humoral response against encoded transgenes, and (b) preexisting immunity to Ad is highly prevalent among the general population. To overcome these obstacles, we constructed an Ad-based malaria vaccine by inserting a B cell epitope derived from a Plasmodium yoelii circumsporozoite (CS) protein (referred to as the PyCS-B epitope) into the capsid proteins of WT/CS-GFP, a recombinant Ad expressing P. yoelii CS protein and GFP as its transgene. Multiple vaccinations with the capsid-modified Ad induced a substantially increased level of protection against subsequent malaria challenge in mice when compared with that of unmodified WT/CS-GFP. Increased protection correlated with augmented antibody responses against the PyCS-B epitope expressed in the capsid. Furthermore, replacement of hypervariable region 1 (HVR1) of the Ad capsid proteins with the PyCS-B epitope circumvented neutralization of the modified Ad by preexisting Ad-specific antibody, both in vivo and in vitro. Importantly, the immunogenicity of the Ad-containing PyCS-B epitope in the HVR1 and a P. yoelii CS transgene was maintained. Overall, this study demonstrates that the HVR1-modifed Ad vastly improves upon Ad as a promising malaria vaccine platform candidate.

Efficient development of plasmodium liver stage-specific memory CD8+ T cells during the course of blood-stage malarial infection

Immunity to Plasmodium liver stages in individuals in malaria-endemic areas is inextricably linked to concomitant blood-stage parasitemia. Although Plasmodium sporozoite infection induces measurable CD8+ T cell responses, the development of memory T cells during active erythrocytic infection remains uncharacterized. Using transgenic T cells, we assessed antigen-specific effector CD8+ T cell responses induced by normal (NorSpz) and radiation-attenuated (IrrSpz) Plasmodium yoelii sporozoites. The magnitude, phenotypic activation, and differentiation pathway of CD8+ T cells were similarly induced by NorSpz and IrrSpz. Moreover, in normal mice, memory T cells elicited after priming with NorSpz and IrrSpz generated identical recall responses after a heterologous boost strategy. Furthermore, these recall responses exhibited comparable in vivo antiparasite activity. Our results indicate that sporozoites that retain their infective capacity induce memory CD8+ T cells that are robustly recalled by secondary immunization. Thus, erythrocytic infection does not preclude the establishment of memory CD8+ T cell responses to malarial liver stages.

Priming of CD8+ T cell responses following immunization with heat-killedPlasmodiumsporozoites

Protective immune responses against malaria are induced by immunization with radiation-attenuated Plasmodium sporozoites. In contrast, non-viable, heat-killed sporozoites do not induce protection, emphasizing the requirement for live parasites to achieve effective immune responses. Using an experimental system with CD8+ T cells from T cell receptor-transgenic mice, we analyzed the primary CD8+ T cell responses elicited by heat-killed inactivated sporozoites. We found that the numbers of specific CD8+ T cells induced were much lower compared to when immunizing with attenuated sporozoites; however, the kinetics of activation and the phenotype of these T cells were similar in both groups. Despite their low frequency after priming, high numbers of specific CD8+ T cells were observed after boosting with a recombinant vaccinia virus. Upon induction of the recall response, the same level of protection was observed when either heat-killed or attenuated sporozoites were used for priming. We propose that live parasites are not critical for the induction of memory T cell populations against the malaria liver stages.

Antigen targeting to dendritic cells elicits long-lived T cell help for antibody responses

Resistance to several prevalent infectious diseases requires both cellular and humoral immune responses. T cell immunity is initiated by mature dendritic cells (DCs) in lymphoid organs, whereas humoral responses to most antigens require further collaboration between primed, antigen-specific helper T cells and naive or memory B cells. To determine whether antigens delivered to DCs in lymphoid organs induce T cell help for antibody responses, we targeted a carrier protein, ovalbumin (OVA), to DCs in the presence of a maturation stimulus and assayed for antibodies to a hapten, (4-hydroxy-3-nitrophenyl) acetyl (NP), after boosting with OVA-NP. A single DC-targeted immunization elicited long-lived T cell helper responses to the carrier protein, leading to large numbers of antibody-secreting cells and high titers of high-affinity antihapten immunoglobulin Gs. Small doses of DC-targeted OVA induced higher titers and a broader spectrum of anti-NP antibody isotypes than large doses of OVA in alum adjuvant. Similar results were obtained when the circumsporozoite protein of Plasmodium yoelii was delivered to DCs. We conclude that antigen targeting to DCs combined with a maturation stimulus produces broad-based and long-lived T cell help for humoral immune responses.

Mechanism of androgen-induced thymic atrophy in the wall lizard, Hemidactylus flaviviridis: an in vitro study

The present in vitro study demonstrates the effect of androgen on thymocyte apoptosis leading to thymic atrophy in the wall lizard, Hemidactylus flaviviridis. Thymocytes collected from castrated lizards were incubated with varying concentrations of dihydrotestosterone (DHT) to observe its effect on proliferation and apoptosis. DHT treatment reduced the tritiated thymidine incorporation in thymocytes, suggesting that androgen directly inhibits thymocyte proliferation. It also caused apoptosis of thymocytes effectively at 10(-7)M. However, the increased apoptotic action of DHT was indirectly mediated through thymic epithelial cell-rich stromal cell components (TEC). This observation was reaffirmed by in vitro incubation of thymocytes with DHT-pretreated TEC-conditioned medium. However, the DHT-induced TEC-secreted apoptotic factors could induce thymocyte DNA fragmentation only when DHT was added to the conditioned medium. It implies that DHT priming of thymocytes is required for the apoptotic effect of DHT-induced TEC-secreted factor. DHT-induced thymocyte apoptosis was found to be caspase-dependent since it activated the initiator (caspase-9) and effector caspases (caspases-3 and -7) as well as cleaved the enzyme substrate poly(ADP-ribose) polymerase (PARP). Further, the apoptotic effect of DHT was routed through its classical receptors, as non-steroidal antiandrogen flutamide blocked the DHT-induced thymocyte apoptosis. The inhibition of apoptosis by transcription/translation inhibitors further substantiates the genomic pathway of DHT action. It can be concluded that DHT, in addition to inhibiting thymocyte proliferation directly, accelerates caspase-dependent apoptotic process in thymocytes indirectly through TEC via a genomic pathway. Nevertheless, the priming of thymocytes with DHT is required for the apoptotic effect of TEC-secreted factor.

Yellow fever 17D as a vaccine vector for microbial CTL epitopes: protection in a rodent malaria model

The yellow fever vaccine 17D (17D) is safe, and after a single immunizing dose, elicits long-lasting, perhaps lifelong protective immunity. One of the major challenges facing delivery of human vaccines in underdeveloped countries is the need for multiple injections to achieve full efficacy. To examine 17D as a vector for microbial T cell epitopes, we inserted the H-2K^d–restricted CTL epitope of the circumsporozoite protein (CS) of Plasmodium yoelii between 17D nonstructural proteins NS2B and NS3. The recombinant virus, 17D-Py, was replication competent and stable in vitro and in vivo. A single subcutaneous injection of 10⁵ PFU diminished the parasite burden in the liver by ∼70%. The high level of protection lasted between 4 and 8 wk after immunization, but a significant effect was documented even 24 wk afterwards. Thus, the immunogenicity of a foreign T cell epitope inserted into 17D mimics some of the remarkable properties of the human vaccine. Priming with 17D-Py followed by boosting with irradiated sporozoites conferred sterile immunity to 90% of the mice. This finding indicates that the immune response of vaccine-primed individuals living in endemic areas could be sustained and magnified by the bite of infected mosquitoes.

In vitro effect of FSH and testosterone on Sertoli cell nursing function in wall lizard Hemidactylus flaviviridis (Rüppell)

The present in vitro Sertoli cell-enriched culture study was aimed to understand the precise role of FSH and testosterone either alone or in combination in regulation of Sertoli cell nursing function such as lactate production, which in turn is utilized by the germ cells as an energy substrate. The stimulatory effect of FSH on lactate production by Sertoli cell-enriched culture was significantly enhanced when FSH and dihydrotestosterone were supplemented in the medium either simultaneously or DHT was added 12 h later to FSH (0 h FSH+12 h DHT). On the contrary, DHT alone or added 12 h prior to FSH (0 h DHT+12 h FSH) in the incubation medium, significantly reduced the lactate secretion by Sertoli cells as compared to control or FSH alone/FSH+DHT simultaneously/0 h FSH+12 h DHT, respectively. This provides the conclusive evidence that androgen has additive effect on nursing function of Sertoli cell-enriched clusters only when they are in an activated state in response to gonadotropin.

Glucocorticoid-induced thymocyte apoptosis in wall lizard Hemidactylus flaviviridis

The aim of the present study is to demonstrate the phenomenon and mechanism of GC-induced cell death of thymocytes in wall lizard Hemidactylus flaviviridis. Lizard thymocytes were treated in vitro with different concentration of corticosterone (CS) for varying durations and the genomic DNA was analyzed both by agarose gel electrophoresis and flow cytometry. Corticosterone induced DNA fragmentation in a dose-dependent manner, as the DNA laddering was more prominent at 10(-14) M than at lower concentrations. However, CS could activate the programmed cell death of thymocytes only when incubated for 48 h and not at 3, 6, 12, or 24 h. Similar results were obtained following the flow cytometric analysis. The highest apoptotic cell death was noted at 10(-14) M concentration. CS-induced programmed cell death was decreased dramatically when the thymocytes were preincubated with RU 486 (10(-9) ng /ml) for 24 h, suggesting the classical receptor-mediated genomic pathway of glucocorticoid action in inducing apoptosis of thymocytes in wall lizard H. flaviviridis.

Thymic structural changes in relation to seasonal cycle and testosterone administration in wall lizard Hemidactylus flaviviridis (Ruppell)

Light microscopic and ultrastructural studies of thymus in wall lizard showed remarkable season dependent structural changes. In winter, the thymus was involuted and its cortico-medullary differentiation was not distinct. Thymocytes were sparsely distributed. The epithelial cells exhibited atrophic features such as an appreciable decrease in the nuclear-cytoplasmic ratio and accordingly reduction in cell organelles. The reconstruction of thymus commenced during spring and it became fully developed with marked delineation of cortico-medullary regions during summer. The thymus was then densely populated with thymocytes and epithelial cells showed voluminous cytoplasm having numerous cell organelles. The thymus regression started again by the beginning of autumn. The results suggest that the thymic development in wall lizard have inverse relationship with the androgen level, as the testicular steroidogenic activity was seen maximum during winter and least in summer. This assumption gets support by castration and testosterone replacement experiments. Castration of lizards during winter resulted in profound development of thymus with an appreciable increase in thymocytes mainly in the cortex region . The cortex became delineated from the medulla. Following testosterone treatment, the thymus underwent regression and was comparable to testis-intact lizard's thymus during winter season. After withdrawal of testosterone treatment, the thymus exhibited dense lymphoid and thymocyte population with a demarcation of cortico-medullary regions and sub-cortical region was regenerated.

In vitro effect of temperature on phagocytic and cytotoxic activities of splenic phagocytes of the wall lizard, Hemidactylus flaviviridis

The in vitro effect of temperature on phagocytosis, nitric oxide production and interleukin-1 (IL-1) secretion by splenic phagocytes isolated from the wall lizard (Hemidactylus flaviviridis) demonstrated that changes in temperature altered non-specific defenses. The LPS-induced percentage phagocytosis and phagocytic index were recorded maximum at 25 degrees C. The phagocytic activity declined considerably when the phagocytes were incubated at low (7 and 15 degrees C) or high (37 degrees C) temperatures. The presence of bacterial lipopolysaccharide (LPS) in the incubation medium could considerably enhance the phagocytic activity of splenic phagocytes. A similar temperature-related effect was also observed on LPS-induced cytotoxic activity of phagocytes. LPS could stimulate the nitrite release indicating nitric oxide production only at 25 degrees C. Likewise, the proliferative responses of immature rat's thymocytes to LPS-induced phagocyte-conditioned medium suggest that IL-1 secretion was enhanced when phagocytes were cultured at 25 degrees C. This suggests that 25 degrees C is the optimal temperature for phagocyte functions in H. flaviviridis. The decrease or increase in temperature other than at 25 degrees C dramatically suppressed the phagocyte activities.

Epididymal protein secretion and its androgenic control in wall lizards Hemidactylus flaviviridis (Ruppell)

The total protein level in different segments of epididymis of normal lizard exhibited noticeable increase from early February to late March of a same reproductive phase. Comparison among the protein level of different epididymal segments showed insignificant variation from anterior to posterior part in early February but in late March, the protein level in posterior segment was appreciably higher than in anterior and middle segments. Further, testosterone-induced epididymal protein did not exhibit any significant quantitative variation among different regions. The electrophoretic pattern of luminal fluid from different epididymal regions of normal lizard showed 28 protein bands without any marked regional difference. However, only 16 protein bands could be demonstrated in the epididymal fluid of any region. Unlike molecular size, isoelectric focussing of testosterone induced epididymal proteins revealed that three regions of epididymis differ in their nature of protein. The number of proteins having alkaline pH range in anterior and middle regions were 4 and 3, respectively which increased upto 6 in posterior region.

Sexual dimorphism in phagocytic activity of wall lizard's splenic macrophages and its control by sex steroids

The splenic macrophages of wall lizards exhibited marked sex-related difference in their phagocytic activity. The percentage phagocytosis and phagocytic index in females was considerably higher than that of males. Gonadectomy resulted in significant increase in percentage phagocytosis and phagocytic index in both male as well as female lizards, suggesting that gonadal hormones inhibit macrophage phagocytosis. This was further confirmed by dose and time-related in vivo and in vitro experiments in which DHT suppressed phagocytosis which increased with dose or duration of treatment, while E(2) either suppressed or had no effect on phagocytosis, depending on dose and duration of treatment. Exposure of macrophages to steroid receptor antagonists, cyproterone acetate (CPA), or tamoxifen citrate (Tam) prior to treatment with their respective sex steroids markedly reduced the DHT- or E(2)-modulated suppression of macrophage phagocytosis. It is concluded that the sex steroids modulate splenic macrophage phagocytosis via receptor-mediated systems.

Activation of the JAK-STAT pathway by reactive oxygen species

Reactive oxygen species (ROS) play an important role in the pathogenesis of many human diseases, including the acute respiratory distress syndrome, Parkinson's disease, pulmonary fibrosis, and Alzheimer's disease. In mammalian cells, several genes known to be induced during the immediate early response to growth factors, including the protooncogenes c-fos and c-myc, have also been shown to be induced by ROS. We show that members of the STAT family of transcription factors, including STAT1 and STAT3, are activated in fibroblasts and A-431 carcinoma cells in response to H2O2. This activation occurs within 5 min, can be inhibited by antioxidants, and does not require protein synthesis. STAT activation in these cell lines is oxidant specific and does not occur in response to superoxide- or nitric oxide-generating stimuli. Buthionine sulfoximine, which depletes intracellular glutathione, also activates the STAT pathway. Moreover, H2O2 stimulates the activity of the known STAT kinases JAK2 and TYK2. Activation of STATs by platelet-derived growth factor (PDGF) is significantly inhibited by N-acetyl-L-cysteine and diphenylene iodonium, indicating that ROS production contributes to STAT activation in response to PDGF. These findings indicate that the JAK-STAT pathway responds to intracellular ROS and that PDGF uses ROS as a second messenger to regulate STAT activation.

Screening for chlamydial infections in women with pelvic inflammatory diseases

One hundred female patients clinically diagnosed as pelvic inflammatory disease (PID) were studied for the presence of chlamydial infection by cytology and antigen detection. Cervical smears stained by Giemsa revealed inclusion bodies, only in 3 percent of cases. While using Immunocomb Enzyme Immunoassay (EIA) test, antigen was detected in 13% of cases, thereby showing that antigen detection is a better method than cell cytology. A significant correlation with the low socioeconomic status and younger age group was seen in patients showing presence of Chlamydia trachomatis antigen.

Sex steroid hormones modulate the activation of murine peritoneal macrophages: receptor mediated modulation

The comparative dose and time-dependent effects of male and female sex steroid hormones on nitrite release by murine peritoneal macrophages (M phi) stimulated by LPS were studied. M phi from gonadectomized mice released larger amounts of nitrite on LPS stimulation than controls; although nitrite release was significantly greater in castrated males than in ovariectomized females, suggesting that sex hormone deprivation results in an increase in nitrite release. This was further confirmed by in vitro treatment of M phi with estradiol (E2), testosterone (T) and progesterone (P) at different doses and duration prior to, and during, stimulation of nitrite production by LPS. E2 (except at 10(-2) ng/ml), T and P significantly (P < 0.05) suppressed the nitrite release in a dose-dependent manner. Nitrite release from M phi increased with decreasing exposure time to E2, T and P. Preincubation of M phi with sex hormones prior to LPS treatment also reduced nitrite production. Sex steroid receptor antagonists tamoxifen citrate, cyproterone acetate/flutamide and RU486 markedly reduced the inhibitory effect of E2, T and P, respectively, suggesting that sex hormones modulate M phi nitrite release via a receptor-mediated system.

Epididymal influence on acquisition of sperm motility in the gekkonid lizard Hemidactylus flaviviridis

Total sperm count and percent sperm motility were noted in different parts of the epididymis, and the effect of anterior, middle, and posterior epididymal fluid on the induction of motility of nonmotile testicular spermatozoa was observed. The results were used to compare the influence of different parts of epididymis of Hemidactylus flaviviridis on the acquisition of sperm motility, which is a sign of sperm maturation. Spermatozoa collected from different regions of the ductus epididymidis showed considerable difference in their motility as well as total count with an increase from anterior to posterior region. The epididymal fluids from different regions induced the motility of testicular spermatozoa and the induction accelerated with increasing fluid volume and incubation period. Epididymal fluid at higher volumes induced the motility of nonmotile testicular spermatozoa significantly even at short-term incubation. Among different epididymal regions, fluid from posterior was more potent in influencing the motility than the fluids of middle and anterior. Motility pattern of spermatozoa varied from zig-zag, circular, and erratic in anterior to wavy in posterior region of epididymis. However, the mean sperm velocity did not show any regional variation.

Effects of cyproterone acetate on FSH and testosterone influenced spermatogenesis, steroidogenesis and epididymis in the Indian wall lizard, Hemidactylus flaviviridis (Ruppell)

The effects of FSH, testosterone and either cyproterone acetate (CPA) alone or in combination with FSH or testosterone on testis and epididymis in male lizards were studied histologically and histochemically during recrudescent phase to find out whether the onset of spermatogenesis is androgen dependent or FSH dependent. The testes of control lizards consisted of mainly spermatogonia, a few primary spermatocytes and secondary spermatocytes rarely. The interstitial or Leydig cells were atrophied. FSH treatment induced spermatogenic activity substantially as indicated by increase in number of primary and secondary spermatocytes and transformation of secondary spermatocytes into spermatids and into spermatozoa in a few cases. Besides, steroidogenic activity was also remarkably stimulated as evidences by considerable depletion of sudanophilic lipid and an increase in Delta5-3beta-hydroxysteroid dehydrogenase enzyme activity in Leydig cells. However, testosterone treatment resulted in the inhibition of spermatogenesis. A significant inhibition of spermatogenesis was noted in lizards treated either with CPA alone or in combination with FSH. The inhibitory effect of CPA on spermatogenesis was increased when it was given in combination with testosterone. The results indicate that onset of spermatogenic activity is dependent on FSH (or FSH-like protein), but not on the androgen. The ductus epididymidis in control lizards was regressed with low cuboidal epithelium. The lumen of the tubules was totally devoid of secretory material and spermatozoa. FSH treatment induced a marked hypertrophy in epididymidis. The lumen became filled with secretory material mixed with spermatozoa. The hypertrophy in epididymidis was also recorded after the treatment with testosterone, but the degree of induction was not to that extent as noted in FSH treated ones. However, CPA injected either with FSH or with testosterone resulted in the profound atrophy in epididymidis.

Testis and epididymis of the Indian wall lizard (Hemidactylus flaviviridis): effects of flutamide on FSH and testosterone influenced spermatogenesis, Leydig cell, and epididymis

To determine the separate spermatogenic actions of FSH and testosterone, adult male lizards Hemidactylus flaviviridis with recrudescent testes were administered the non-steroidal antiandrogen flutamide either alone or in combination with FSH or testosterone, and the histology and histochemistry of the testes and ductus epididymides were studied. Flutamide-treated animals displayed a marked hypertrophy of Leydig cells. A few spermatids were also seen in testis of more than half the animals treated with flutamide. Flutamide also produced a significant increase of primary spermatocytes; no spermatids were observed in controls. A significant inhibition of spermatogenesis was noted in lizards treated either with testosterone alone or in combination with flutamide. Ovine FSH treatment caused a significant stimulation of spermatogenesis, as indicated by the increase of primary and secondary spermatocytes and the transformation of secondary spermatocytes into spermatids or, in a few cases, into spermatozoa. A considerable depletion of sudanophilic lipid and moderate delta 5-3 beta-hydroxysteroid dehydrogenase activity was noted in the Leydig cells of FSH-treated animals indicating enhanced steroidogenesis. Similar results were obtained when lizards were treated with flutamide + FSH. The effects of simultaneous treatment of flutamide with FSH or testosterone on ductus epididymidis revealed that flutamide markedly inhibited the epithelial cell height and lumen diameter with a loss of luminal content when compared to FSH or testosterone-treated lizards.

Breast feeding practices and maternal employment

Little information exists about the relationship between maternal employment and breast feeding practices and knowledge about lactation. The study was conducted on 318 employed and 299 non-employed women prospectively. Lactational practices were significantly influenced by employment status, with 81.9% non-employed vs. only 49.7% employed going in for exclusive breast feeds in the first 3 months (p less than .001). Correspondingly, 46.8% employed women started combined breast and bottle feeds from birth (p less than .001). Within the employed group, parity and social class did not significantly alter the infant feeding practices. Employed women were better informed about feeding and weaning as compared to their non-employed counterparts (36.8% vs. 18.4% p less than .001). Women from higher social class also tended to be more aware (59.8% vs. 7.2%: p less than .001). Multiparas had an edge over primiparas with respect to knowledge about lactation (36.1% vs. 20.1% p less than .01).

Effects of cyproterone acetate and flutamide on the testis and epididymis of the Indian wall lizard, Hemidactylus flaviviridis (Ruppell)

Intramuscular injections of 0.2 mg cyproterone acetate (CA) or flutamide every other day for 6 weeks resulted in the inhibition of spermatogenesis. While CA treatment reduced the weight of the testis significantly, flutamide did not. Inhibition of steroidogenesis, indicated by an accumulation of sudanophilic lipid and a decrease in delta 5-3 beta-hydroxysteroid dehydrogenase and glucose-6-phosphate dehydrogenase activity, was evident in the Leydig cells of CA-treated testis. Flutamide, on the other hand, had no effect on the activity of Leydig cells. A marked decline in epididymal weight, as well as reduction in epithelial cell height, was caused by both CA and flutamide. The epithelial cells of epididymes of treated lizards exhibited an accumulation of sudanophilic lipid material in their cytoplasm. However, sudanophilic secretions present in the lumina of epididymal tubules were greatly reduced. This indicates either lack of synthesis of lipid or decrease in its turn over. Our results are in agreement with those obtained in mammalian species after CA or flutamide treatment where a decrease in fertility is suggested.