Characterisation of plasmodium proteins playing critical roles in mosquito midgut infection and malaria transmission

Malaria parasites undergo dramatic losses during their gametocyte-to-ookinete-to- oocyst developmental transition. This PhD thesis primarily aimed to use the Signature Tagged Mutagenesis (STM) methodology to simultaneously phenotype pools of individually tagged P. berghei mutants, of genes previously found to be highly upregulated during the gametocyte-to-ookinete-to-oocyst developmental transition stages and possibly involved in mosquito-parasite interactions. Although the first pool of mutants acted as a proof-of-concept experiment, it revealed three novel Plasmodium genes with essential functions during the parasite ookinete-to-oocyst-to- sporozoite transition. Specifically, AQP2 is essential for sporozoite formation in the developing oocyst, N38 is important for the gametocyte-to-ookinete developmental transition and N350 is critical for ookinete motility prior to midgut invasion The mosquito complement-like system is responsible for the greatest parasite population bottleneck observed during the ookinete-to-oocyst developmental transition, which also coincides with the ookinete traversal through the mosquito midgut epithelium. Therefore, this PhD also aimed to shed light on the molecular mechanisms mediated by the mosquito innate immune system to clear the Plasmodium parasites and thus regulate the infection outcome. Several P. berghei genes have been identified to play an essential role in the parasite protection from the mosquito complement responses including c01, PIMMS43, P47 and c57. Knockout of any of these genes leads to ookinete elimination by the mosquito complement-like reactions upon reaching the basal sub-epithelial space, unless silencing key factors of the mosquito complement system. Based on these findings, it was further suggested that (i) either all of these genes have essential functions in parasite immune evasion, or (ii) their loss-of-function bears a fitness cost that exceeds a certain threshold required for parasites to endure the mosquito complement responses. Serial mouse- to-mosquito-to-mouse transmission cycles followed by allele quantification revealed that the mosquito complement system is responsible for instantly removing 99% of the introduced in the population knockout alleles. This study offers new perspectives for further understanding the mosquito-parasite interactions leading to malaria transmission

PIMMS43 is required for malaria parasite immune evasion and sporogonic development in the mosquito vector.

After being ingested by a female Anopheles mosquito during a bloodmeal on an infected host, and before they can reach the mosquito salivary glands to be transmitted to a new host, Plasmodium parasites must establish an infection of the mosquito midgut in the form of oocysts. To achieve this, they must first survive a series of robust innate immune responses that take place prior to, during, and immediately after ookinete traversal of the midgut epithelium. Understanding how parasites may evade these responses could highlight new ways to block malaria transmission. We show that an ookinete and sporozoite surface protein designated as PIMMS43 (Plasmodium Infection of the Mosquito Midgut Screen 43) is required for parasite evasion of the Anopheles coluzzii complement-like response. Disruption of PIMMS43 in the rodent malaria parasite Plasmodium berghei triggers robust complement activation and ookinete elimination upon mosquito midgut traversal. Silencing components of the complement-like system through RNAi largely restores ookinete-to-oocyst transition but oocysts remain small in size and produce a very small number of sporozoites that additionally are not infectious, indicating that PIMMS43 is also essential for sporogonic development in the oocyst. Antibodies that bind PIMMS43 interfere with parasite immune evasion when ingested with the infectious blood meal and significantly reduce the prevalence and intensity of infection. PIMMS43 genetic structure across African Plasmodium falciparum populations indicates allelic adaptation to sympatric vector populations. These data add to our understanding of mosquito-parasite interactions and identify PIMMS43 as a target of malaria transmission blocking

PIMMS43 is required for malaria parasite immune evasion and sporogonic development in the mosquito vector.

After being ingested by a female Anopheles mosquito during a bloodmeal on an infected host, and before they can reach the mosquito salivary glands to be transmitted to a new host, Plasmodium parasites must establish an infection of the mosquito midgut in the form of oocysts. To achieve this, they must first survive a series of robust innate immune responses that take place prior to, during, and immediately after ookinete traversal of the midgut epithelium. Understanding how parasites may evade these responses could highlight new ways to block malaria transmission. We show that an ookinete and sporozoite surface protein designated as PIMMS43 (Plasmodium Infection of the Mosquito Midgut Screen 43) is required for parasite evasion of the Anopheles coluzzii complement-like response. Disruption of PIMMS43 in the rodent malaria parasite Plasmodium berghei triggers robust complement activation and ookinete elimination upon mosquito midgut traversal. Silencing components of the complement-like system through RNAi largely restores ookinete-to-oocyst transition but oocysts remain small in size and produce a very small number of sporozoites that additionally are not infectious, indicating that PIMMS43 is also essential for sporogonic development in the oocyst. Antibodies that bind PIMMS43 interfere with parasite immune evasion when ingested with the infectious blood meal and significantly reduce the prevalence and intensity of infection. PIMMS43 genetic structure across African Plasmodium falciparum populations indicates allelic adaptation to sympatric vector populations. These data add to our understanding of mosquito-parasite interactions and identify PIMMS43 as a target of malaria transmission blocking

A qualitative study of stakeholder views on the use of a digital app for supported self-management in early intervention services for psychosis

Abstract Background Digital tools such as Smartphones have the potential to increase access to mental health support including self-management interventions for individuals with psychosis, and ultimately to improve outcomes. Self-management strategies, including relapse prevention and crisis planning and setting personal recovery goals, are intended to assist people with long-term conditions to take an active role in their recovery, with evidence for a range of benefits. However, their implementation is inconsistent, and access and uptake need to be improved. The current study explores the acceptability of a Smartphone app (My Journey 3) that has been developed to facilitate supported self-management in Early Intervention in Psychosis (EIP) services. Methods Semi-structured one-to-one interviews were conducted with twenty-one EIP service users who had access to My Journey 3 as part of a feasibility trial, and with thirteen EIP service clinicians who were supporting service users with the app. Interviews focused on the acceptability and usability of My Journey 3. Data was coded to themes based on the Acceptability of Healthcare Interventions framework. Results Many service user participants found My Journey 3 to be acceptable. The symptom and medication trackers in particular were described as helpful. A smaller number of service users disliked the intervention. Individual-level factors that appeared to influence acceptability and engagement included recovery stage and symptom severity. Clinicians tended to report that My Journey 3 was a potentially positive addition to service users’ care, but they often felt unable to provide support due to competing demands in their work, which in turn may have impacted acceptability and usage of the app. Conclusions Our findings suggest that the app is perceived as having potential to improve users’ capacity to self-manage and work towards recovery goals, but barriers prevented many clinicians providing consistent and effective support as intended. Further evaluation of supported self-management apps in psychosis is warranted but needs to address implementation challenges from the start

The Community Navigator Study: Results from a feasibility randomised controlled trial of a programme to reduce loneliness for people with complex anxiety or depression.

BACKGROUND:Loneliness is common among people with mental health problems and predicts poorer recovery from depression and anxiety. Needs for support with loneliness and social relationships are often under-addressed in mental health services. The Community Navigator programme was designed to reduce loneliness for adults (aged 18 and above) with complex depression or anxiety who were using secondary mental health services. Acceptability and feasibility of the programme and a trial evaluation were tested in a feasibility randomised controlled trial with qualitative evaluation. METHODS:Forty participants with depression or anxiety using secondary mental health services were recruited from mental health services in two London sites and randomised to receive: the Community Navigator programme over six months in addition to routine care (n = 30); or routine care (n = 10). Measures of loneliness, depression, other clinical and social outcomes and service use were collected at baseline and six-months follow-up. Levels of engagement in the programme and rates of trial recruitment and retention were assessed. Programme delivery was assessed through session logs completed by Community Navigators. The acceptability of the programme was explored through qualitative interviews (n = 32) with intervention group participants, their family and friends, programme providers and other involved staff. RESULTS:Forty participants were recruited in four months from 65 eligible potential participants asked. No one withdrew from the trial. Follow-up interviews were completed with 35 participants (88%). Process records indicated the programme was delivered as intended: there was a median of seven meetings with their Community Navigator (of a maximum ten) per treatment group participant. Qualitative interviews indicated good acceptability of the programme to stakeholders, and potential utility in reducing loneliness and depression and anxiety. CONCLUSIONS:A definitive, multi-site randomised controlled trial is recommended to evaluate the effectiveness and cost-effectiveness of the Community Navigator programme for people with complex anxiety and depression in secondary mental health services