Parasite Invasion Research Articles

Exploring genetic variation and phylogenetic patterns of Tropilaelaps mercedesae (Mesostigmata: Laelapidae) populations in Asia

IntroductionThe mites belonging to the genus Tropilaelaps are ectoparasites of honey bees, primarily infesting the larval and pupal stages. Originating from subtropical regions, these mites can cause brood malformation, bee mortality, and subsequent decline or absconding of colonies.Material and methodsDuring field surveys conducted in Nepal, South Korea, and Uzbekistan to investigate honey bee pests, several populations of T. mercedesae were collected. This is the first record of T. mercedesae from Uzbekistan. The morphological characteristics of the collected populations were analyzed, and their phylogenetic relationship with other Asian populations was examined.Results and discussionThe molecular analysis of cytochrome oxidase I gene revealed high similarity between Uzbekistan and Pakistan populations, signaling the potential invasion of subtropical honey bee parasites into the Central Asian beekeeping sectors. Phylogenetic analysis indicated the presence of four distinct lineages within the mainland-Indonesian populations of T. mercedesae. Notably, an evolutionary divergence was observed between the haplotypes from Sri Lanka and the Philippines compared to the remaining mainland Asian and Indonesian haplotypes, suggesting the possible existence of subspecies or separate species in these isolated locations. To gain a deeper understanding of this phenomenon, it is essential to continue monitoring the spread of this significant honey bee pest and conduct comprehensive morphological and molecular analyses of samples collected from these specific localities.

Plasmodium falciparum Glutamic Acid-Rich Protein-Independent Polyclonal Antibodies Inhibit Malaria Parasite Growth in Human Erythrocytes.

Plasmodium falciparum glutamic acid-rich protein (PfGARP) is a recently characterized cell surface antigen encoded by Plasmodium falciparum, the causative agent of severe human malaria pathophysiology. Previously, we reported that the human erythrocyte band 3 (SLC4A1) serves as a host receptor for PfGARP. Antibodies against PfGARP did not affect parasite invasion and growth. We surmised that PfGARP may play a role in the rosetting and adhesion of malaria. Another study reported that antibodies targeting PfGARP exhibit potent inhibition of parasite growth. This inhibition occurred without the presence of any immune or complement components, suggesting the activation of an inherent density-dependent regulatory system. Here, we used polyclonal antibodies against PfGARP and a monoclonal antibody mAb7899 to demonstrate that anti-PfGARP polyclonal antibodies, but not mAb7899, exerted potent inhibition of parasite growth in infected erythrocytes independent of PfGARP. These findings suggest that an unknown malaria protein(s) is the target of growth arrest by polyclonal antibodies raised against PfGARP.

Enhanced Antimalarial and Antisequestration Activity of Methoxybenzenesulfonate-Modified Biopolymers and Nanoparticles for Tackling Severe Malaria.

Severe malaria is a life-threatening condition that is associated with a high mortality. Severe Plasmodium falciparum infections are mediated primarily by high parasitemia and binding of infected red blood cells (iRBCs) to the blood vessel endothelial layer, a process known as sequestration. Here, we show that including the 5-amino-2-methoxybenzenesulfonate (AMBS) chemical modification in soluble biopolymers (polyglutamic acid and heparin) and poly(acrylic acid)-exposing nanoparticles serves as a universal tool to introduce a potent parasite invasion inhibitory function in these materials. Importantly, the modification did not add or eliminated (for heparin) undesired anticoagulation activity. The materials protected RBCs from invasion by various parasite strains, employing both major entry pathways. Two further P. falciparum strains, which either expose ligands for chondroitin sulfate A (CSA) or intercellular adhesion molecule 1 (ICAM-1) on iRBCs, were tested in antisequestration assays due to their relevance in placental and cerebral malaria, respectively. Antisequestration activity was found to be more efficacious with nanoparticles vs gold-standard soluble biopolymers (CSA and heparin) against both strains, when tested on receptor-coated dishes. The nanoparticles also efficiently inhibited and reversed the sequestration of iRBCs on endothelial cells. First, the materials described herein have the potential to reduce the parasite burden by acting at the key multiplication stage of reinvasion. Second, the antisequestration ability could help remove iRBCs from the blood vessel endothelium, which could otherwise cause vessel obstruction, which in turn can lead to multiple organ failure in severe malaria infections. This approach represents a further step toward creation of adjunctive therapies for this devastating condition to reduce morbidity and mortality.

Parasitic infestations as a cause of episodic angioedema

Angioedema (AO) is a localized transient acute, recurrent edema of the skin or mucous membranes. Vasoactive substances play a key role in the development of AO: histamine, tryptase, prostaglandin, bradykinin, which lead to a reversible increase in endothelial permeability. Usually, the manifestations persist from 2 hours to several days and in most cases disappear without a trace, without additional therapy. ICD-10 CODE: T 78.3 - angioedema, D 84.1 - defect in the complement system. The purpose of the study. The purpose of the study is to study the features of episodic angioedema as a manifestation of parasitic invasion Materials and methods. The clinical case of a 10-year-old boy who was hospitalized in the pediatric department as planned with complaints of recurrent swelling of the eyelids, perianal area, itchy skin, hemorrhagic rashes, abdominal pain was analyzed. These symptoms are noted periodically for 2.5 years. The child’s anamnestic data, allergoanamnesis, gender characteristics, and the structure of the main diagnoses were analyzed. The results of laboratory and instrumental research methods were evaluated (including the level of C1 inhibitor for differential diagnosis with hereditary angioedema). Results. The results of the study. For 2.5 years, the child was periodically hospitalized in various hospitals with symptoms of periorbital edema and abdominal pain. These symptoms persisted from 2 weeks to 2 months. And they were registered with a frequency of 2 months. Blood tests showed an increase in IgE by 10 times, IgG to helminths by 6 times. At normal values of the C1 inhibitor. During the EGDS, a large number of roundworms were discovered. The normal level of the C1 inhibitor, as well as the absence of similar signs of the disease in the child’s closest relatives (autosomal dominant type of inheritance) made it possible to exclude hereditary angioedema with a high degree of probability. Conclusion. The data obtained during the analysis allowed us to conclude that parasitic invasion may be the cause of angioedema in children. Blood eosinophilia, as one of the important indicators of parasitic invasion, may be absent during the long course of infection. The presence of elevated total immunoglobulin E and positive minimum levels of antibodies to helminths in the blood should alert doctors in terms of further search for parasitic invasion.

Extreme heat reduces host and parasite performance in a butterfly-parasite interaction.

Environmental temperature fundamentally shapes insect physiology, fitness and interactions with parasites. Differential climate warming effects on host versus parasite biology could exacerbate or inhibit parasite transmission, with far-reaching implications for pollination services, biocontrol and human health. Here, we experimentally test how controlled temperatures influence multiple components of host and parasite fitness in monarch butterflies (Danaus plexippus) and their protozoan parasites Ophryocystis elektroscirrha. Using five constant-temperature treatments spanning 18-34°C, we measured monarch development, survival, size, immune function and parasite infection status and intensity. Monarch size and survival declined sharply at the hottest temperature (34°C), as did infection probability, suggesting that extreme heat decreases both host and parasite performance. The lack of infection at 34°C was not due to greater host immunity or faster host development but could instead reflect the thermal limits of parasite invasion and within-host replication. In the context of ongoing climate change, temperature increases above current thermal maxima could reduce the fitness of both monarchs and their parasites, with lower infection rates potentially balancing negative impacts of extreme heat on future monarch abundance and distribution.

Possible connection between intestinal tuft cells, ILC2s and obesity.

Intestinal tuft cells (TCs) are defined as chemosensory cells that can "taste" danger and induce immune responses. They play a critical role in gastrointestinal parasite invasion, inflammatory bowel diseases and high-fat diet-induced obesity. Intestinal IL-25, the unique product of TCs, is a key activator of type 2 immunity, especially to promote group 2 innate lymphoid cells (ILC2s) to secret IL-13. Then the IL-13 mainly promotes intestinal stem cell (ISCs) proliferation into TCs and goblet cells. This pathway formulates the circuit in the intestine. This paper focuses on the potential role of the intestinal TC, ILC2 and their circuit in obesity-induced intestinal damage, and discussion on further study and the potential therapeutic target in obesity.

Neospora caninum surface antigen 1 is a major determinant of the pathogenesis of neosporosis in nonpregnant and pregnant mice.

NcSAG1 is one of most widely investigated antigens of Neospora caninum in various research fields. Such studies demonstrated the proficiency of NcSAG1 in the regulatory process of parasite adhesion and invasion of host cells. Accordingly, the contribution of NcSAG1 to the pathogenesis of neosporosis can undoubtedly be extrapolated, but direct evidence is lacking. Herein, we provide the first successful attempt at the gene disruption of NcSAG1 and novel data on the invasion and virulence potentials of N. caninum in vitro and in vivo. The disruption of the NcSAG1 gene was applied using the CRISPR/Cas9 system and confirmed by PCR, western blot and indirect fluorescent antibody tests as NcSAG1 knockout parasites (NcSAG1KO). Then, we investigated the role of NcSAG1 in the growth kinetics of the parasite in vitro. The deletion of the NcSAG1 gene significantly decreased the infection rate and reduced the egress rate of the parasite. An in vivo study using nonpregnant female and male BALB/c mice revealed a significantly higher survival rate and lower body weight change in the group infected with the NcSAG1KO parasite than in the parental strain (Nc-1)-infected group. Regarding the vertical transmission model of BALB/c mice, the absence of the NcSAG1 gene significantly enhanced the survival of pups and greatly lowered the parasite burden in the brains of pups. In conclusion, our study suggested NcSAG1 as a key molecule in the pathogenesis of N. caninum.

The Role of Tumor Necrosis Factor Alpha in Adolescent Iraqi Children Infected with Toxoplasmasis

Toxoplasmosis affects various biochemical markers, which has garnered attention recently. Toxoplasmosis biochemical marker values were the focus of this study. To evaluate the infection-related marker TNF alpha, TNF-α regulates inflammation, anti-tumor responses, and homeostasis via interacting with TNF-R1 and TNF-R2. TNF-α has a vital function in treating T. gondii by regulating hematopoietic stem and progenitor cell development. Despite therapeutic usage of anti-TNF-α medications, adverse effects such lymph proliferative disorders have been known to occur. This also suggests that one major mechanism by which cytokines operate is by inhibiting parasite invasion. TNF-α has the ability to directly influence the proliferation of intracellular parasites to different extents. The study included one hundred patients with toxoplasmosis, aged between eighteen and thirty years old. Among them, seventy had confirmed cases of infection, with forty samples from both male and female patients, while the remaining thirty samples were taken from healthy individuals serving as a control group. Baghdad Teaching Hospital, Al-Yarmouk Teaching Hospital, and many outpatient clinics will treat patients from different Iraqi governorates from November 2022 and October 2023. Additionally, we utilized the ELISA technique to determine the quantity of TNF-alpha present. With this study, there were no significant changes in blood levels of TNF-α between the control group and teens of different ages and genders, according to the results. The mean ±SE values of the level in healthy teens (80.57 ±5.27) and T. gondii patients (123.59 ±4.35, 158.85 ±10.26) were not statistically different. The findings indicated that the mean values for healthy teenagers were 66.02 ±5.89 and 87.84 ±3.24, respectively. There was no significant gender difference, with mean values of 149.65 ±11.98 and 133.25 ±3.96, respectively. Patients with toxoplasmosis exhibited substantially higher TNF-α levels than the control group (P ≤0.01). The average ± SE TNF-alpha levels in teenagers infected with T. gondii were 136.86 ±5.96, whereas the control group had 87.84 ±3.24. Our research suggests that Toxoplasma gondii have the capability to exert effect on certain indicators, such as TNF-alpha. The findings indicate that adolescents are prone to a significant prevalence of toxoplasmosis diagnoses. Consequently, prioritizing health education for those with a heightened susceptibility to developing the disease is imperative.

РЕТРОСПЕКТИВНЫЙ АНАЛИЗ ЗАБОЛЕВАЕМОСТИ ОПИСТОРХОЗОМ В АЛТАЙСКОМ КРАЕ ЗА 2011-2022 гг.

Introduction. Currently, opisthorchiasis presents a pressing and socially significant challenge in practical healthcare. Among biohelminthiasis, opisthorchiasis holds the highest incidence and significantly impacts population health. Aim. This study aims to conduct a retrospective epidemiological analysis of opisthorchiasis incidence in the Altai Krai (AK) from 2011 to 2022. Materials and Methods. The study utilized statistical form No. 2 of the Federal State Statistical Observation "Information on infectious and parasitic diseases" for 2011-2022. Intensive and extensive indicators were calculated, along with the arithmetic mean (X) and standard error of the mean (m). Statistical analysis was performed using the Microsoft Excel program. The mapping method was employed to identify spatial patterns, correlations, and combinations of geographically expressed phenomena. Results. Between 2011 and 2022, there was a notable trend towards a 2-fold decrease in opisthorchiasis morbidity in the Altai region, with rates dropping from 54.44±1.500/0000 to 29.85±0.900/0000. This decrease, while significant, still represented an 8.5% excess compared to the Russian Federation. However, in 2022, there was a concerning spike in morbidity, which was 2.3 times higher than the levels seen in the period of 2020-2021. This increase could potentially be linked to reduced healthcare-seeking behavior due to the impact of the COVID-19 epidemic. The highest rates of infection were observed among the adult population and children aged 7 to 17 years, averaging at 39.63±4.200/0000. Urban areas showed a striking 64.9% excess in opisthorchiasis morbidity compared to rural regions. Specifically, twelve administrative districts, along with the cities of Barnaul and Belokurikha, stood out with rates exceeding 74.600/0000. This heightened prevalence was attributed to their proximity to the Ob River and water bodies hosting carp fish species infected with opisthorchis larvae, with an average long-term infection rate of 7.2%. Conclusions. The endemic nature of opisthorchiasis in the Altai region, centered around the Ob River, combined with the significant infection levels in carp fish consumed by the local population, underscores the urgent need for enhanced epidemiological surveillance. Utilizing modern mathematical data processing techniques is crucial to bolster the efficacy of therapeutic, diagnostic, and preventive measures against this parasitic invasion.

A single-pass type I membrane protein, mannose-specific L-type lectin, potentially involved in the adhesion and invasion of Cryptosporidium parvum.

Cryptosporidium is a globally distributed zoonotic protozoan parasite that can cause severe diarrhea in humans and animals. L-type lectins are carbohydrate-binding proteins involved in multiple pathways in animals and plants, including protein transportation, secretion, innate immunity, and the unfolded protein response signaling pathway. However, the biological function of the L-type lectins remains unknown in Cryptosporidium parvum. Here, we preliminarily characterized an L-type lectin in C. parvum (CpLTL) that contains a lectin-leg-like domain. Immunofluorescence assay confirmed that CpLTL is located on the wall of oocysts, the surface of the mid-anterior region of the sporozoite and the cytoplasm of merozoites. The involvement of CpLTL in parasite invasion is partly supported by experiments showing that an anti-CpLTL antibody could partially block the invasion of C. parvum sporozoites into host cells. Moreover, the recombinant CpLTL showed binding ability with mannose and the surface of host cells, and competitively inhibited the invasion of C. parvum. Two host cell proteins were identified by proteomics which should be prioritized for future validation of CpLTL-binding. Our data indicated that CpLTL is potentially involved in the adhesion and invasion of C. parvum.

ВЕТСАНЭКСПЕРТИЗА И МОРФОЛОГИЯ КРОВИ МОЛОДИ ВОБЛЫ ПРИ ПАРАЗИТАРНОЙ ИНВАЗИИ

A study of the morphological parameters of the peripheral blood of juvenile volva during parasitic invasions by trematodes A. muehlingi and P. cuticula was carried out to study the degree of negative impact of these parasites on early juvenile vobla. The analysis confirmed that parasitic invasion influenced changes in hematological parameters. A natural increase in the number of neutrophils and eozonophils in infested fish was shown. Reliably high rates of young erythrocytes were revealed, twice as high as in fish free from parasites. The identified deviations in the composition of the white blood of juvenile roach were due to the protective mechanism and immunological reactions of the body to infection by parasites. The presence of degenerative forms of erythrocytes in blood smears of both infected and uninfected early juvenile vobla may indicate that these changes are caused not only by the parasitic load, but also by negative changes in abiotic environmental factors.

Current challenges in addressing invasive diseases in domestic pigeons: insights from our research

The current study aims to highlight the ongoing challenges in addressing invasive diseases within pigeon flocks in the Lublin region. The study material comprised bird faecal samples from 69 flocks (39 fancy pigeon flocks and 30 racing pigeon flocks) with a total estimated bird count of 7,490, as declared by the owners. Parasite forms were confirmed in samples from 56/69 flocks, indicating a prevalence of 81.2% across the study, 87.2% in fancy pigeon flocks and 73.3% in racing pigeon flocks. The identified parasites included protozoa of the genus Eimeria, roundworms Ascaridia columbae, nematodes Capillariidae, Ornithostrongylus quadriradiatus, and Syngamus trachea, cestodes and Trichomonas gallinae. The analysis revealed that coccidiosis was the predominant invasion in both racing and fancy pigeon flocks. Comparing the two types of breeding (racing pigeons and fancy pigeons), fancy pigeon flocks were more susceptible to parasitic invasions.

Retrograde cholangioscopy in differential diagnosis of parasitic invasion

The authors present differential diagnosis of parasitic invasion of the common bile duct. A 52-year-old patient admitted with malignant bile duct obstruction, mechanical jaundice, cholestatic hepatitis and cholangitis. Bile duct tumor was preliminary diagnosed according to anamnesis, complaints, physical, laboratory and instrumental data. Retrograde cholangiopancreatography, endoscopic papillotomy and revision of the common bile duct were performed. There was occlusion at the level of the upper third of the common bile duct. Retrograde cholangioscopy was performed to clarify the nature of obstruction and tumor. Cholangioscopy revealed parasites in the common bile duct that required extraction. The patient was sent to the infectious disease hospital.

Rational Engineering of an Antimalarial Peptide with Enhanced Proteolytic Stability and Preserved Parasite Invasion Inhibitory Activity

We describe the rational chemical engineering to enhance proteolytic stability of a chimeric peptide using a combination of unique strategies that involve the incorporation of a series of D-amino acids...

Analysis of the individual condition of hares (Lepus europaeus Pall.) based on the body weight, KFI index, and pathological changes in selected internal organs

The study aimed to demonstrate the relationship between the presence of pathomorphological changes in the liver, heart, and kidneys of hares Lepus europaeus, and their individual condition expressed by body weight and the KFI index. The material for the study consisted of 70 hares harvested during two consecutive hunting seasons, 2021/2022 and 2022/2023, in two hunting districts in the western part of the Lublin Upland. Forty hares were examined in 2021/2022, and 30 were examined in 2022/2023. Pathomorphological changes were detected in 89% of the hares, and 14% of the hares with pathomorphological changes suffered from a parasitic invasion of the liver. In the group of hares with pathomorphological lesions, the poorest individual condition expressed by the body weight and kidney fat index (KFI) was found in individuals with a parasitic infection of the liver. This may indicate that parasites play a crucial role in the deterioration of the individual condition of hares and may have a negative impact on the survival and reproduction of the entire population.

Novel stem cell technologies are powerful tools to understand the impact of human factors on Plasmodium falciparum malaria.

Plasmodium falciparum parasites have a complex life cycle, but the most clinically relevant stage of the disease is the invasion of erythrocytes and the proliferation of the parasite in the blood. The influence of human genetic traits on malaria has been known for a long time, however understanding the role of the proteins involved is hampered by the anuclear nature of erythrocytes that makes them inaccessible to genetic tools. Here we overcome this limitation using stem cells to generate erythroid cells with an in-vitro differentiation protocol and assess parasite invasion with an adaptation of flow cytometry to detect parasite hemozoin. We combine this strategy with reprogramming of patient cells to Induced Pluripotent Stem Cells and genome editing to understand the role of key genes and human traits in malaria infection. We show that deletion of basigin ablates invasion while deletion of ATP2B4 has a minor effect and that erythroid cells from reprogrammed patient-derived HbBart α-thalassemia samples poorly support infection. The possibility to obtain patient-secific and genetically modifed erythoid cells offers an unparalleled opportunity to study the role of human genes and polymorphisms in malaria allowing preservation of the genomic background to demonstrate their function and understand their mechanisms.

A rhoptry protein, localizing in the bulb region of rhoptries, could induce protective immunity against Eimeria tenella infection.

Rhoptry organelle proteins (ROPs) secreted by apicomplexan parasites play important roles during parasites invasion and survival in host cells, and are potential vaccine candidates against apicomplexan diseases. Eimeria tenella (E. tenella) is one of the most noteworthy apicomplexan species, which causes hemorrhagic pathologies. Although dozens of putative E. tenella ROP sequences are annotated, most ROP proteins are not well studied. In this study, an E. tenella ROP21 gene was identified and the recombinant EtROP21 protein (rEtROP21) was expressed in Escherichia coli. The developmental expression levels, localization, and protective efficacy against E. tenella infection in chickens were studied. An EtROP21 gene fragment with an open reading frame (ORF) of 981 bp was obtained from the Beijing strain of E. tenella. The rEtROP21 has a molecular weight of approximately 50 kDa and was recognized by rEtROP21-immunized mouse serum. Two specific protein bands, about 43 KDa and 95 KDa in size, were detected in the whole sporozoite proteins using the rEtROP21-immunized chicken serum. RT-qPCR analysis of the E. tenella ROP21 gene (EtROP21) revealed that its mRNA levels were higher in merozoites and sporozoites than in sporulated and unsporulated oocysts. Immunofluorescence and immunoelectron analyses showed that the EtROP21 protein predominantly localizes in the bulb region of rhoptries distributed at anterior, posterior, and perinuclear regions of E. tenella sporozoites. Immunization and challenge experiments revealed that immunizing chickens with rEtROP21 significantly increased their average body weight gain while decreasing mean lesion score and oocyst output (P <0.05). When compared with the challenged control group, the rEtROP21-immunized group was associated with a significantly higher relative weight gain (90.2%) and a greater reduction in oocyst output (67%) (P <0.05). The anticoccidial index of the rEtROP21-immunized group was 163.2. Chicken serum ELISA revealed that the levels of the specific anti- rEtROP21 antibody, IFN-γ, and IL-4 were significantly higher in the rEtROP21-immunized group than in the challenged control group (P <0.05). These results indicate that rEtROP21 can induce a high level of specific immune response and it is a potential candidate for the development of vaccines against E. tenella infection in chickens.

Gene expression levels and inhibitory effect of 7-[(7-methoxy-4,5-dihydro-1H-benzo[g]indazol-3-yl)carbonyl]-2-phenyl-5,6,7,8-tetrahydropyrazolo[1,5-a]pyrido[4,3-d]Pyrimidin-9(1H)-one (MCL) against AP2-I and BDP1 in malaria experimental models

Resistance to antimalarial drugs leads a global recurrence of malaria, posing a significant challenge to malaria control. This study aimed to assess gene expression and resistance profiles in clinical isolates, and validate the inhibitory effect of MCL compound against PbAP2-I and PbBDP1 genes in vivo. Malaria prevalence rate throughout the clinical study period stood at 12.24%. Blood samples were obtained from 182 malaria outpatients and 30 P. berghei-infected mice treated with varying MCL concentrations. DNA and RNA were extracted. PfAP2-I, PfBDP1, PfMDR1, and PfK13 genes were amplified using Real-time qPCR and sequenced for mutation profiling. Relative gene expression of AP2-I and BDP1 genes in P. falciparum and P. berghei-treated mice was carried out by Reverse-transcription PCR. The data were analyzed using ANOVA at P<0.05 indicating a significant difference. Relative gene expression results from clinical isolates showed PfAP2-I and PfBDP1 are highly expressed in the trophozoite and schizont stages. The clinical isolates show conserved nucleotide sequences for PfAP2-I, PfBDP1, and PfK13 genes compared to the 3D7 strain. However, Asn86Tyr mutation implicated in antimalarial drug resistance and Leu1312Iso mutation not previously reported to be associated with antimalarial drug resistance were observed for the PfMDR1 gene. MCL inhibited the expression of PbAP2-I (by 4.52 and 8.08 folds) and PbBDP1 (by 37.92 and 79.07 folds) at 40µM and 50µM concentrations after a 7-day, single oral daily dose. Our findings validate MCL's inhibitory activity against AP2-I and BDP1 genes, hence representing potential new targets of antimalarial therapy for controlling malaria parasite invasion.

Babesia bovis RON2 binds to bovine erythrocytes through a highly conserved epitope

B. bovis invasion of bovine erythrocytes requires tight junction formation involving AMA-1/RON2 complex interaction. RON2 has been considered a vaccine candidate since antibodies targeting the protein can inhibit parasite invasion of target cells; however, the mechanism controlling B. bovis RON2 interaction with red blood cells is not yet fully understood. This study was thus aimed at identifying B. bovis RON2 protein regions associated with interaction with bovine erythrocytes. Natural selection analysis of the ron2 gene identified predominantly negative selection signals in the C-terminal region. Interestingly, protein-cell and competition assays highlighted the RON2-C region’s role in peptide 42918-mediated erythrocyte binding, probably to a sialoglycoprotein receptor. This peptide (1218SFIMVKPPALHCVLKPVETL1237) lies within an intrinsically disordered region of the RON2 secondary structure flanked by two helical residues. The study provides, for the first time, valuable insights into RON2’s role in interaction with its target cells. Future studies are required for studying the peptide’s potential as an anti-B. bovis vaccine component.

Protein kinase PfPK2 mediated signalling is critical for host erythrocyte invasion by malaria parasite.

Signalling pathways in malaria parasite remain poorly defined and major reason for this is the lack of understanding of the function of majority of parasite protein kinases and phosphatases in parasite signalling and its biology. In the present study, we have elucidated the function of Protein Kinase 2 (PfPK2), which is known to be indispensable for the survival of human malaria parasite Plasmodium falciparum. We demonstrate that it is involved in the invasion of host erythrocytes, which is critical for establishing infection. In addition, PfPK2 may also be involved in the maturation of the parasite post-invasion. PfPK2 regulates the release of microneme proteins like Apical Membrane Antigen 1 (AMA1), which facilitates the formation of Tight Junction between the merozoite and host erythrocyte- a key step in the process of invasion. Comparative phosphoproteomics studies revealed that PfPK2 may be involved in regulation of several key proteins involved in invasion and signalling. Furthermore, PfPK2 regulates the generation of cGMP and the release of calcium in the parasite, which are key second messengers for the process of invasion. These and other studies have shed light on a novel signalling pathway in which PfPK2 acts as an upstream regulator of important cGMP-calcium signalling, which plays an important role in parasite invasion.