Negotiation of collective and individual candidacy for long Covid healthcare in the early phases of the Covid-19 pandemic: Validated, diverted and rejected candidacy

This analysis of people's accounts of establishing their need and experiences of healthcare for long Covid (LC) symptoms draws on interview data from five countries (UK, US, Netherlands, Canada, Australia) during the first ∼18 months of the Covid-19 pandemic when LC was an emerging, sometimes contested, condition with scant scientific or lay knowledge to guide patients and professionals in their sense-making of often bewildering constellations of symptoms. We extend the construct of candidacy to explore positive and (more often) negative experiences that patients reported in their quest to understand their symptoms and seek appropriate care. Candidacy usually considers how individuals negotiate healthcare access. We argue a crucial step preceding individual claims to candidacy is recognition of their condition through generation of collective candidacy. "Vanguard patients" collectively identified, named and fought for recognition of long Covid in the context of limited scientific knowledge and no established treatment pathways. This process was technologically accelerated via social media use. Patients commonly experienced "rejected" candidacy (feeling disbelieved, discounted/uncounted and abandoned, and that their suffering was invisible to the medical gaze and society). Patients who felt their candidacy was "validated" had more positive experiences; they appreciated being believed and recognition of their changed lives/bodies and uncertain futures. More positive healthcare encounters were described as a process of "co-experting" through which patient and healthcare professional collaborated in a joint quest towards a pathway to recovery. The findings underpin the importance of believing and learning from patient experience, particularly vanguard patients with new and emerging illnesses.

"I'm the Family Ringmaster and Juggler": Autistic Parents' Experiences of Parenting During the COVID-19 Pandemic

Background

Little is known about autistic parenthood. The literature that exists suggests that autistic parents can find it difficult to manage the everyday demands of parenting and domestic life. While emerging research has also highlighted more positive parenting experiences, greater understanding of autistic parenthood is needed.

Objective

This study sought to understand autistic parents' parenting experiences during the initial phase of the COVID-19 pandemic.

Methods

Thirty-five Australian autistic parents (95% women) of autistic children (aged 4-25 years) took part in semi-structured interviews designed to elicit their experiences of life during lockdown. We used reflexive thematic analysis using an inductive (bottom-up) approach to identify patterned meanings within the data set.

Results

Autistic parents repeatedly spoke of how the lockdown brought some initial relief from the intensity of their usual lives caring for their children. Nevertheless, most autistic parents felt that the "cumulative stress" of trying to juggle everything during lockdown proved very challenging, which eventually took its toll on parents' mental health. Parents were aware that they needed support but found it difficult to reach out to their usual social supports (including autistic friends) for help, and formal supports were virtually nonexistent. Consequently, they felt "very much forgotten." Nevertheless, they described how their connections with their children grew stronger over lockdown as they focused on nurturing their children's "mental health ahead of everything else."

Conclusions

Our analysis shows how challenging conventional life can be for autistic parents. Parenting requires grappling with a distinctive set of demands, which are usually partially manageable through the informal supports many autistic parents draw upon. The relative absence of informal supports during the pandemic, however, left them reliant on more formal supports, which were not forthcoming. Research is urgently needed to identify the most effective formal supports for autistic parents, ideally in partnership with autistic parents themselves.

Co-design of an NHS primary care health check for autistic adults

Autistic people experience more health conditions and earlier mortality. This study investigated views about a primary care health check for autistic adults to inform its design. Fifty-one people participated in consultation groups and interviews, comprising autistic adults (some with co-occurring intellectual disabilities), adults with intellectual disabilities, supporters and health professionals. Participants wanted the health check to cover physical and mental health and social functioning. They emphasised the importance of sharing information about individual needs and associated adjustments before the health check. They highlighted the need to change the way healthcare services communicate with autistic people, such as reducing phone contact and booking appointments online. They wanted individual choice in how the health check was completed, with video call or email offered alongside face-to-face. Participants raised the need for further training of primary care staff on autism, to highlight the diversity of experiences of autistic people and ways in which difficulties, such as pain, may present differently. Clinicians raised questions about the capacity of mental health and social care services to meet the additional needs potentially identified through the health check. This study represents a key step in the development and co-design of a UK primary care health check for autistic people.

Lay abstract

Autistic people are on average more likely to experience poor health than people who are not autistic. Health checks have been shown to improve access to effective healthcare. This study investigated people’s views about a primary care health check for autistic adults. We held discussion groups and interviewed autistic adults, adults with intellectual disabilities, supporters and health professionals. People wanted the health check to look at a person’s physical and mental health, and how they were doing socially. They thought people should be able to share information about their needs and the reasonable adjustments they would like before the health check. They wanted healthcare services to change the way they communicate with autistic people, such as being able to book appointments online rather than by telephone. They wanted a choice in how the health check was completed, with video call or email offered as well as face-to-face appointments. People thought further training of primary care staff on autism was needed, to increase awareness of the diversity of experiences of autistic people and ways in which difficulties, such as pain, may present differently to non-autistic people. Clinicians raised questions about whether mental health and social care services could meet the additional needs that might be identified through the health check. We used this information to design an NHS primary care health check for autistic people in collaboration with autistic people, supporters and health professionals.

New aspects of DNA recognition by group II WRKY transcription factor revealed by structural and functional study of AtWRKY18 DNA binding domain

WRKY transcription factors (TFs) constitute one of the largest families of plant TFs. Based on the organization of domains and motifs, WRKY TFs are divided into three Groups (I-III). The WRKY subgroup IIa includes three representatives in A. thaliana, AtWRKY18, AtWRKY40, and AtWRKY60, that participate in biotic and abiotic stress responses. Here we present crystal structures of the DNA binding domain (DBD) of AtWRKY18 alone and in the complex with a DNA duplex containing the WRKY-recognition sequence, W-box. Subgroup IIa WRKY TFs are known to form homo and heterodimers. Our data suggest that the dimerization interface of the full-length AtWRKY18 involves contacts between the DBD subunits. DNA binding experiments and structural analysis point out novel aspects of DNA recognition by WRKY TFs. In particular, AtWRKY18-DBD preferentially binds an overlapping tandem of W-boxes accompanied by a quasi-W-box motif. The binding of DNA deforms the B-type double helix, which suggests that the DNA fragment must be prone to form a specific structure. This can explain why despite the short W-box consensus, WRKY TFs can precisely control gene expression. Finally, this first experimental structure of a Group II WRKY TF allowed us to compare Group I-III representatives.

Exploring the Experience of Seeking an Autism Diagnosis as an Adult

Background

Emerging research suggests that seeking an autism diagnosis as an adult is usually difficult and time-consuming but brings relief once a diagnosis is made. This study explored the experience of the pathway to an autism diagnosis during adulthood for adults living in Australia.

Methods

We conducted a qualitative phenomenological study and interviewed 13 adults who identified as autistic about their pathway to autism diagnosis in their mode of choice. Spoken interviews were transcribed verbatim, and transcripts were analyzed by using a thematic approach.

Results

Data analysis resulted in 6 themes and 20 meaning units that described the experiences of adults seeking an autism diagnosis in Australia. These themes involved two interwoven journeys that spanned before, during, and after the diagnostic process. The personal journey involved feeling different, considering autism, and living as autistic, whereas the clinical journey involved missed opportunities, varied diagnostic experiences, and absent supports.

Conclusions

Given the potential benefits for adults obtaining a formal autism diagnosis and accessing post-diagnostic supports, it is important that health professionals and governments collaborate to reduce access barriers and ensure adequate services are available. The findings from this study informed the development of Australia's national guideline for autism diagnosis.

A trial of the AASPIRE healthcare toolkit with Australian adults on the autism spectrum

BACKGROUND

Autistic adults experience barriers to accessing health care, such as service provider communication not meeting their needs, healthcare facilities causing sensory discomfort and feeling fear or anxiety regarding their healthcare visit. The Academic Autism Spectrum Partnership in Research and Education (AASPIRE) developed and trialled an online healthcare toolkit to reduce such barriers and improve healthcare interactions between autistic adults and their primary care providers in the United States. This preliminary study aimed to explore experiences of autistic adults using the AASPIRE Healthcare Toolkit in Australia.

METHODS

Semi-structured interviews were conducted with six autistic adults about their experiences and perceptions of utilising the toolkit in an Australian healthcare setting.

RESULTS

Participants identified that the toolkit facilitated their interactions with health professionals by providing structure to appointments, supplementing new knowledge and increasing individual confidence. They also offered suggestions to tailor the toolkit for use in Australia.

CONCLUSIONS

Future research should seek to explore the experiences of autistic adults using a version of the toolkit adapted for Australian use, as well as exploring the views of health professionals utilising it.

Cryo-EM reconstructions of BMV-derived virus-like particles reveal assembly defects in the icosahedral lattice structure

The increasing interest in virus-like particles (VLPs) has been reflected by the growing number of studies on their assembly and application. However, the formation of complete VLPs is a complex phenomenon, making it difficult to rationally design VLPs with desired features de novo. In this paper, we describe VLPs assembled in vitro from the recombinant capsid protein of brome mosaic virus (BMV). The analysis of VLPs was performed by Cryo-EM reconstructions and allowed us to visualize a few classes of VLPs, giving insight into the VLP self-assembly process. Apart from the mature icosahedral VLP practically identical with native virions, we describe putative VLP intermediates displaying non-icosahedral arrangements of capsomers, proposed to occur before the final disorder-order transition stage of icosahedral VLP assembly. Some of the described VLP classes show a lack of protein shell continuity, possibly resulting from too strong interaction with the cargo (in this case tRNA) with the capsid protein. We believe that our results are a useful prerequisite for the rational design of VLPs in the future and lead the way to the effective production of modified VLPs.

Poly(C)-binding Protein 2 Regulates the p53 Expression via Interactions with the 5'-Terminal Region of p53 mRNA

The p53 protein is one of the major transcriptional factors which guards cell homeostasis. Here, we showed that poly(C)-binding protein 2 (PCBP2) can bind directly to the 5′ terminus of p53 mRNA by means of electrophoretic mobility shift assay. Binding sites of PCBP2 within this region of p53 mRNA were mapped using Pb2+-induced cleavage and SAXS methods. Strikingly, the downregulation of PCBP2 in HCT116 cells resulted in a lower level of p53 protein under normal and stress conditions. Quantitative analysis of p53 mRNA in PCBP2-downregulated cells revealed a lower level of p53 mRNA under normal conditions suggesting the involvement of PCBP2 in p53 mRNA stabilisation. However, no significant change in p53 mRNA level was observed upon PCBP2 depletion under genotoxic stress. Moreover, a higher level of p53 protein in the presence of rapamycin or doxorubicin and the combination of both antibiotics was noticed in PCBP2-overexpressed cells compared to control cells. These observations indicate the potential involvement of PCBP2 in cap-independent translation of p53 mRNA especially occurring under stress conditions. It has been postulated that the PCBP2 protein is engaged in the enhancement of p53 mRNA stability, probably via interacting with its 3′ end. Our data show that under stress conditions PCBP2 also modulates p53 translation through binding to the 5′ terminus of p53 mRNA. Thus PCBP2 emerges as a double-function factor in the p53 expression.

3D Domain Swapping Dimerization of the Receiver Domain of Cytokinin Receptor CRE1 From Arabidopsis thaliana and Medicago truncatula

Cytokinins are phytohormones regulating many biological processes that are vital to plants. CYTOKININ RESPONSE1 (CRE1), the main cytokinin receptor, has a modular architecture composed of a cytokinin-binding CHASE (Cyclases/Histidine kinases Associated Sensory Extracellular) domain, followed by a transmembrane fragment, an intracellular histidine kinase (HK) domain, and a receiver domain (REC). Perception of cytokinin signaling involves (i) a hormone molecule binding to the CHASE domain, (ii) CRE1 autophosphorylation at a conserved His residue in the HK domain, followed by a phosphorelay to (iii) a conserved Asp residue in the REC domain, (iv) a histidine-containing phosphotransfer protein (HPt), and (v) a response regulator (RR). This work focuses on the crystal structures of the REC domain of CRE1 from the model plant Arabidopsis thaliana and from the model legume Medicago truncatula. Both REC domains form tight 3D-domain-swapped dimers. Dimerization of the REC domain agrees with the quaternary assembly of the entire CRE1 but is incompatible with a model of its complex with HPt, suggesting that a considerable conformational change should occur to enable the signal transduction. Indeed, phosphorylation of the REC domain can change the HPt-binding properties of CRE1, as shown by functional studies.

COVID-19, social isolation and the mental health of autistic people and their families: A qualitative study

LAY ABSTRACT

In this study, we show that autistic people and their families have found it very difficult to deal with the lockdowns during the COVID-19 pandemic. Autistic and non-autistic researchers spoke to 144 people, including 44 autistic adults, 84 parents of autistic children and 16 autistic young people (12-18 years old). We asked them about their everyday lives and mental health during lockdown. People told us that they enjoyed having fewer obligations and demands compared to pre-COVID-19 life. They felt that life was quieter and calmer. But people also told us again and again how much they missed meeting people in real life, especially their friends, and their therapists and support workers. People told us that their mental health suffered because they did not have contact with their friends and services. Importantly, many people (including researchers) think that autistic people do not want friends or to be around people. But our results show that is not true. Many autistic people do want friends and to be around other people. Some people's mental health has been damaged by not being able to see people during COVID-19. Autistic people need support in many areas of life so they can keep socialising and seeing their friends even through difficult times, like pandemics.

Development and psychometric testing of the AASPIRE Adult Autism Healthcare Provider Self-Efficacy Scale

LAY ABSTRACT

The adult healthcare system is ill-prepared to provide high-quality care to autistic adults. Lack of provider training may contribute to the problem, but there are few previously tested survey instruments to guide provider training efforts. Our objective was to develop and test a measure of healthcare providers' confidence (or "self-efficacy") in providing healthcare to autistic adults and to use it to better understand their training needs. We used a community-based participatory research (CBPR) approach, in partnership with academic researchers, autistic adults, supporters, and healthcare providers, throughout the project. We developed a one-page questionnaire and surveyed 143 primary care providers from eight primary care clinics in Oregon and California, United States. Preliminary testing of the AASPIRE Adult Autism Healthcare Provider Self-Efficacy Scale suggests that the measure is reliable and valid. Using this scale, we found only a minority of providers reported high confidence in communicating with patients (25%); performing physical exams or procedures (43%); accurately diagnosing and treating other medical issues (40%); helping patients stay calm and comfortable during visits (38%); identifying accommodation needs (14%); and making necessary accommodations (16%). While providers need training across all aspects of care related to autism in adulthood, interventions should pay particular attention to helping providers communicate with patients, and identify and make necessary accommodations. Future research is needed to further validate this scale and to understand how to meet providers' training needs most effectively.

Psychometric testing of a set of patient-reported instruments to assess healthcare interventions for autistic adults

LAY ABSTRACT

Interventions to improve healthcare for autistic adults are greatly needed. To evaluate such interventions, researchers often use surveys to collect data from autistic adults (or sometimes, their supporters), but few survey measures have been tested for use with autistic adults. Our objective was to create and test a set of patient- or proxy-reported survey measures for use in studies that evaluate healthcare interventions. We used a community-based participatory research (CBPR) approach, in partnership with autistic adults, healthcare providers, and supporters. We worked together to create or adapt survey measures. Three survey measures focus on things that interventions may try to change directly: (1) how prepared patients are for visits; (2) how confident they feel in managing their health and healthcare; and (3) how well the healthcare system is making the accommodations patients feel they need. The other measures focus on the outcomes that interventions may hope to achieve: (4) improved patient-provider communication; (5) reduced barriers to care; and (6) reduced unmet healthcare needs. We then tested these measures in a survey of 244 autistic adults recruited from 12 primary care clinics in Oregon and California, USA (with 194 participating directly and 50 participating via a proxy reporter). Community partners made sure items were easy to understand and captured what was important about the underlying idea. We found the survey measures worked well in this sample. These measures may help researchers evaluate new healthcare interventions. Future research needs to assess whether interventions improve healthcare outcomes in autistic adults.

Recognising, supporting and understanding Autistic adults in general practice settings

BACKGROUND

The health and wellbeing of Autistic people are well below those of their non-Autistic counterparts. With studies showing a reduced life expectancy and poor physical and mental health, it is important that healthcare professionals strive towards improving the lives of Autistic people by recognising those who are undiagnosed and/or misdiagnosed and providing meaningful support.

OBJECTIVE

The aim of this article is to empower general practitioners (GPs) to feel comfortable in recognising potentially undiagnosed Autistic adults. The authors aim to further the understanding of the Autistic experience, including frequently co-occurring physical and mental health conditions, and to give GPs some tools to make the experience of accessing healthcare less problematic for Autistic people.

DISCUSSION

The healthcare experiences of Autistic adults will be greatly improved with a knowledgeable, understanding and accepting GP as the cornerstone of their care.

High-throughput evolutionary optimization of the induction medium towards recombinant protein production in BY-2 tobacco

Bright yellow (BY-2) tobacco cells combined with the XVE chemically inducible system are one of the most promising plant-based platforms for recombinant protein production. This offers a range of benefits, including the separation of the cell growth and heterologous gene expression, lack of risk of infecting the end product with prions and human viruses or appropriate protein glycosylation and folding. However, low protein productivity remains a major obstacle that limits the extensive commercialization of bioproduction in plants. A number of molecular, cell culture and down processing approaches have been made to overcome this problem. Media development for the specific nutritional and hormonal requirements of transgenic plant cells is one of the most efficient cell-culture approaches. We optimized the induction medium towards recombinant protein production in BY-2 and demonstrated the usefulness of evolutionary medium optimization for high-yield protein production in liquid plant cultures. A reliable XVE/GFP model, parallel conducting experiments in a microscale on 96-well plates, and dedicated Gene Game evolutionary optimization software allowed for an effective search of 7611 possible solutions of 11-component media. Within the 4608 formulations tested, the Induct X medium was found with a significant 107.14% increase in protein expression in relation to the standard BY-2 medium.

"It just fits my needs better": Autistic students and parents' experiences of learning from home during the early phase of the COVID-19 pandemic

BACKGROUND AND AIMS

The COVID-19 pandemic has caused unprecedented disruption to people's lives, especially for families, whose children have been taken out of schools during lockdown restrictions and required to learn from home. Little is known, however, about the perceived impact of the lockdown restrictions on the educational experiences of autistic children and young people - a group whose conventional schooling experiences are already often challenging. In this study, we sought to (1) understand these experiences from the perspectives of autistic young people and their parents, and (2) identify the underlying sources of positive experiences at this challenging time, in order to inform the ways in which autistic children might flourish at school in more normal times.

METHODS

Ninety-one Australian participants, including 16 autistic young people aged 12-18 years, 32 autistic parents and 43 non-autistic parents of autistic young people aged 3-18 years, took part in semi-structured interviews about their experiences of life during the initial phase of the COVID-19 pandemic. The interviews were subjected to reflexive, thematic analysis to identify themes and subthemes for each research question.

RESULTS

Overall, our participants initially found the transition to learning from home extremely challenging, with parents reporting that the support received from schools was far from adequate. After that initial period of transition, however, many autistic children reported flourishing at home both educationally and personally. For these children and families, we identified three key ingredients essential to this flourishing, including: (i) the importance of connected, trusting relationships ('people'); (ii) the sensory and social safety of home ('place'); and (iii) the flexibility to pace and structure learning to suit the individual child ('time').

CONCLUSIONS

While the initial COVID-19 lockdown presented many challenges to children learning at home, there were aspects of this otherwise-unsettling situation that enabled children to thrive and from which we can learn for the future.

IMPLICATIONS

These findings have important implications for understanding how and when autistic children might thrive in institutional educational settings once the pandemic subsides, focusing on the relationships between teachers and students, the nature of the physical learning environment and the need for greater flexibility in planning the school day.

Development of consensus-based guidelines for managing communication of individuals with Rett syndrome

Difficulties with communication have a profound impact on the lives of individuals with Rett syndrome and their caregivers. Globally, many families report difficulty accessing appropriate and timely information and services from professionals with expertise in augmentative and alternative communication (AAC) as it pertains to Rett syndrome. To address this need, international consensus-based guidelines for managing the communication of individuals with Rett syndrome were developed by combining available evidence and lived experience with expert opinion. A two-phase Delphi survey was built on statements and recommendations extracted from a review of over 300 pieces of literature combined with survey responses from communication professionals and caregivers. All statements that reached a pre-determined threshold of ≥70% agreement were incorporated into guidelines that consist of 268 statements and recommendations relating to (a) rights of the individual; (b) beliefs and attitudes of communication partners; (c) professional knowledge and team work; (d) strategies to optimize engagement; (e) assessment; and (f) intervention (targets and goals, techniques), including the use of AAC. To date, this project is the largest of its kind, with 650 participants from 43 countries contributing to development of consensus-based guidelines for Rett syndrome.

Cohort profile: the Australian Longitudinal Study of Adults with Autism (ALSAA)

​PURPOSE: There is a significant knowledge gap regarding the lives of adults on the autism spectrum. Some literature suggests significant health and mental health inequalities for autistic adults, yet there is a lack of comprehensive longitudinal studies exploring risk factors. Further, most research does not include the perspective of autistic adults in its conduct or design. Here, we describe the baseline characteristics and inclusive research approach of a nationwide longitudinal study. ​PARTICIPANTS: The Autism Cooperative Research Centre for Living with Autism's Australian Longitudinal Study of Adults with Autism (ALSAA) is a questionnaire-based longitudinal study of autistic adults (25+ years old) with follow-up at 2-year intervals. Autistic advisors were involved in each stage of research apart from data analysis. Three questionnaires were developed: self-report, informant report (ie, proxy report) and carers (ie, carer experiences and characteristics). ​FINDINGS TO DATE: An inclusive research protocol was developed and agreed with autistic advisors. Baseline data were collected from 295 autistic adults (M=41.8 years, SD=12.0) including 42 informant responses, 146 comparison participants and 102 carers. The majority of autistic participants (90%) had been diagnosed in adulthood (M=35.3 years, SD=15.1). When compared with controls, autistic adults scored higher on self-report measures of current depression and anxiety. Participant comments informed ongoing data gathering. Participants commented on questionnaire length, difficulty with literal interpretation of forced response items and expressed gratitude for research in this area. ​FUTURE PLANS: A large comprehensive dataset relating to autistic adults and their carers has been gathered, creating a good platform for longitudinal follow-up repeat surveys and collaborative research. Several outputs are in development, with focus on health service barriers and usage, caregivers, impact of diagnosis in adulthood, further scale validations, longitudinal analyses of loneliness, suicidal ideation, mental illness risk factors and other areas. Baseline data confirm poorer mental health of autistic adults. The ALSAA demonstrates a working approach to inclusive research.

A Systematic Review of What Barriers and Facilitators Prevent and Enable Physical Healthcare Services Access for Autistic Adults

Autistic people are more likely to: be diagnosed with a range of physical health conditions (i.e. cardio-vascular disease); experience premature mortality (for most disease categories); and experience barriers to effectively accessing healthcare. This systematic review sought to identify studies that report on barriers and facilitators to physical healthcare access for autistic people. A total of 3111 records were screened and six studies were included: two quantitative, two qualitative, and two mixed-methodology studies. Patient-provider communication, sensory sensitivities, and executive functioning/planning issues emerged as important barriers to healthcare. Recommendations for clinicians and those planning services are discussed.

Borrelia outer surface protein C is capable of human fibrinogen binding

Outer surface protein C (OspC) is one of the most abundant surface lipoproteins produced during early infection by the Borrelia spirochete, the causative agent of Lyme disease. The high sequence variability of the ospC gene results in the production of several and strongly divergent OspC types. One of the known roles of OspC is the recruitment of blood components, including complement regulators, to facilitate the bloodstream survival of Borrelia at an essential stage of host infection. Here, we identify and describe a new interaction between OspC and human fibrinogen. To test the ability of OspC to bind fibrinogen, we developed a microscale thermophoresis assay using four fluorescently labeled types of OspC. We show that OspC binds fibrinogen tightly, with nanomolar K_d , and that the binding depends on the OspC type. The binding assays combined with SAXS studies allowed us to map the OspC-binding site on the fibrinogen molecule. Spectrometric measurements of fibrinogen clotting in the presence of OspC indicate that OspC negatively influences the clot formation process. Taken together, our findings are consistent with the hypothesis that OspC interacts with blood protein partners to facilitate Borrelia spreading by the hematogenous route.

Choice making in Rett syndrome: a descriptive study using video data

PURPOSE

To describe the choice-making abilities of girls and women with Rett syndrome.

METHOD

Females with Rett syndrome registered with the Australian Rett Syndrome Database with a pathogenic MECP2 mutation were included in this study. Video clips showing choice making in 64 females at a median age of 11.6 years (range 2.3-35.6 years) were analysed. Video clips were coded for the location and nature of the choice-making interaction, and the actions of the communication partner and female with Rett syndrome.

RESULTS

The majority (82.8%, 53/64) of females made a choice, most using eye gaze. Just under half (24/53) used one modality to communicate their choice, 52.8% used two modalities and one used three modalities. Of those who made a choice, 50% did so within 8 s. The length of time to make a choice did not appear to vary with age. During choice making, 57.8% (37/64) of communication partners used language and gestures, 39.1% (25/64) used only language and two used language, gestures and symbols within the interaction.

CONCLUSIONS

The provision of adequate time allowing for a response and observation for the use of multiple modalities could promote effective choice making in females with Rett syndrome. Implications for Rehabilitation The provision of adequate time allowing for a response will promote effective choice making in girls and women with Rett syndrome. Although almost all girls and women with Rett syndrome used eye gaze to indicate their choice, communication partners also need to recognise and respond to other communication modalities that are sometimes used like body movements.

An Exploration of the Use of Eye Gaze and Gestures in Females With Rett Syndrome

PURPOSE

This study investigated the communicative use of eye gaze and gestures in females with Rett syndrome.

METHOD

Data on 151 females with Rett syndrome participating in the Australian Rett Syndrome Database was used in this study. Items from the Communication and Symbolic Behavior Scales Developmental Profile Infant-Toddler Checklist (Wetherby & Prizant, 2002) were used to measure communication. Relationships between the use of eye gaze and gestures for communication were investigated using logistic regression. The influences of MECP2 mutation type, age, and level of motor abilities on the use of eye gaze and gestures were investigated using multivariate linear regression.

RESULTS

Both eye gaze and the use of gestures predicted the ability to make requests. Women aged 19 years or older had the lowest scores for eye gaze. Females with better gross motor abilities had higher scores for the use of eye gaze and gestures. The use of eye gaze did not vary across mutation groups, but those with a C-terminal deletion had the highest scores for use of gestures.

CONCLUSIONS

Eye gaze is used more frequently than gestures for communication, and this is related to age, MECP2 mutation type, and gross motor abilities.

Parental perspectives on the communication abilities of their daughters with Rett syndrome

OBJECTIVE

This study describes, from the perspective of parents, how females with Rett syndrome communicate in everyday life and the barriers and facilitators to successful communication.

METHODS

Sixteen interviews were conducted with parents with a daughter with Rett syndrome with a pathogenic mutation in the methyl-CpG-binding protein 2 gene. Interviews were recorded and transcribed verbatim. Transcripts were analysed using directed content analysis.

RESULTS

All parents reported their daughters were able to express discomfort and pleasure, and make requests and choices using a variety of modalities including vocalisations, body movements and eye gaze. Parents also reported their daughters understood most of what they said and that the level of functional abilities, such as mobility, and environmental factors, such as characteristics of the communication partner, influenced successful communication.

CONCLUSIONS

The perspectives of parents are integral to the assessment of communication abilities and have the potential to inform communication interventions for girls and women with Rett syndrome.

Six Medicago truncatula Dicer-like protein genes are expressed in plant cells and upregulated in nodules

Here we report the existence of six putative Dicer-like genes in the Medicago truncatula genome. They are ubiquitously expressed throughout the plant and significantly induced in root nodules. Over the past decade, small noncoding RNAs (sncRNA) have emerged as widespread and important regulatory molecules influencing both the structure and expression of plant genomes. One of the key factors involved in sncRNA biogenesis in plants is a group of RNase III-type nucleases known as Dicer-like (DCL) proteins. Based on functional analysis of DCL proteins identified in Arabidopsis thaliana, four types of DCLs were distinguished (DCL1-4). DCL1 mainly produces 21 nt miRNAs. The products generated by DCL2, DCL3, and DCL4 belong to various classes of siRNAs that are 22, 24 and 21 nt in length, respectively. M. truncatula is a model legume plant closely related to many economically important cultivable species. By screening the recent M. truncatula genome assembly, we were able to identify three new DCL genes in addition to the MtDCL1-3 genes that had been earlier characterized. The newly found genes include MtDCL4 and two MtDCL2 homologs. We showed that all six M. truncatula DCL genes are expressed in plant cells. The first of the identified MtDCL2 paralogs encodes a truncated version of the DCL2 protein, while the second undergoes substantial and specific upregulation in the root nodules. Additionally, we identified an alternative splicing variant of MtDCL1 mRNA, similar to the one found in Arabidopsis. Our results indicate that DCL genes are differently activated during Medicago symbiosis with nitrogen fixing bacteria and upon pathogen infection. In addition, we hypothesize that the alternative splicing variant of MtDCL1 mRNA may be involved in tissue-specific regulation of the DCL1 level.

Tick receptor for outer surface protein A from Ixodes ricinus - the first intrinsically disordered protein involved in vector-microbe recognition

The tick receptor for outer surface protein A (TROSPA) is the only identified factor involved in tick gut colonization by various Borrelia species. TROSPA is localized in the gut epithelium and can recognize and bind the outer surface bacterial protein OspA via an unknown mechanism. Based on earlier reports and our latest observations, we considered that TROSPA would be the first identified intrinsically disordered protein (IDP) involved in the interaction between a vector and a pathogenic microbe. To verify this hypothesis, we performed structural studies of a TROSPA mutant from Ixodes ricinus using both computational and experimental approaches. Irrespective of the method used, we observed that the secondary structure content of the TROSPA polypeptide chain is low. In addition, the collected SAXS data indicated that this protein is highly extended and exists in solution as a set of numerous conformers. These features are all commonly considered hallmarks of IDPs. Taking advantage of our SAXS data, we created structural models of TROSPA and proposed a putative mechanism for the TROSPA-OspA interaction. The disordered nature of TROSPA may explain the ability of a wide spectrum of Borrelia species to colonize the tick gut.

Efficacy and safety of lenalidomide treatment in multiple myeloma (MM) patients--Report of the Polish Myeloma Group

The aim of the multi-centre retrospective study was to evaluate the efficacy and safety of lenalidomide (LEN) therapy in patients with resistant or relapsed multiple myeloma (MM) as well as in patients with stable disease (LEN used due to neurological complications). The primary endpoint of this study was an overall response rate (ORR). The secondary endpoints were as follows: time to progression (TTP), overall survival (OS) and the safety of drug use. Data were collected in 19 centres of the Polish Multiple Myeloma Study Group. The study group consisted of 306 subjects: 153 females and 153 males. In 115 patients (38.8%, group A), a resistant myeloma was diagnosed; in 135 (44.1%, group B) a relapse, and in 56 (18.3%, group C) a stable disease were stated. In 92.8% of patients, LEN+DEX combination was used; in remaining group, LEN monotherapy or a combination therapy LEN+bortezomib or LEN+bendamustine and other were used. In the entire study group, ORR was 75.5% (including 12.4% patients achieving complete remission [CR] or stringent CR [sCR]). Median time to progression (TTP) was 20 months. Median overall survival (OS) was 33.3 months. The regression model for "treatment response" was on the borderline of statistical significance (p=0.07), however the number of LEN treatment cycles ≥ 6 (R(2)=17.2%), baseline LDH level (R(2)=1.1%) and no ASCT use (R(2)=1.7%) where the factors most affecting treatment response achievement. The regression model for dependant variable--"overall survival"--was statistically significant (p=0.0000004). Factors with the most impact on OS were as follows: number of LEN cycles treatment ≥ 6 (R(2)=16.7%), treatment response achievement (R(2)=6.9%), β-2-microglobulin (β-2-M) level (R(2)=4.8%), renal function (R(2)=3.0%) and lack of 3/4 grade adverse events (R(2)=1.4%).

SUMMARY

LEN is an effective and safe therapeutic option, even in intensively treated resistant and relapsed MM patients, as well as in patients with stable disease and previous treatment-induced neurological complications. In particular, the number of LEN treatment cycles ≥ 6 was the factor which affected treatment response achievement the most, together with an important impact on OS.

The many faces of Dicer: the complexity of the mechanisms regulating Dicer gene expression and enzyme activities

There is increasing evidence indicating that the production of small regulatory RNAs is not the only process in which ribonuclease Dicer can participate. For example, it has been demonstrated that this enzyme is also involved in chromatin structure remodelling, inflammation and apoptotic DNA degradation. Moreover, it has become increasingly clear that cellular transcript and protein levels of Dicer must be strictly controlled because even small changes in their accumulation can initiate various pathological processes, including carcinogenesis. Accordingly, in recent years, a number of studies have been performed to identify the factors regulating Dicer gene expression and protein activity. As a result, a large amount of complex and often contradictory data has been generated. None of these data have been subjected to an exhaustive review or critical discussion. This review attempts to fill this gap by summarizing the current knowledge of factors that regulate Dicer gene transcription, primary transcript processing, mRNA translation and enzyme activity. Because of the high complexity of this topic, this review mainly concentrates on human Dicer. This review also focuses on an additional regulatory layer of Dicer activity involving the interactions of protein and RNA factors with Dicer substrates.

Aspects of speech-language abilities are influenced by MECP2 mutation type in girls with Rett syndrome

This study investigates relationships between methyl-CpG-binding protein 2 gene (MECP2) mutation type and speech-language abilities in girls with Rett syndrome. Cross-sectional data on 766 girls, aged 15 years and under, with genetically confirmed Rett syndrome was obtained from the Australian Rett Syndrome Database (ARSD) (n = 244) and the International Rett Syndrome Phenotype Database (InterRett) (n = 522). Relationships between MECP2 mutation type and age of regression in speech-language abilities, and the level of speech-language abilities before and after this regression were investigated. The females had a median age of 4.95 years in the ARSD and 5.25 years in InterRett. The majority (89%, 685/766) acquired speech-language abilities in the form of babble or words at some point in time. Of those who acquired babble or words, 85% (581/685) experienced a regression in these abilities. Those with a p.Arg133Cys mutation were the most likely to use one or more words, prior to (RRR = 3.45; 95% CI 1.15-10.41) and after (RRR = 5.99; 95% CI 2.00-17.92), speech-language regression. Girls with Rett syndrome vary in their use of speech and language, and in their experience of speech-language regression and these variations are partly explained by genotype.

Characteristics of potential living kidney donors and recipients: donor disqualification reasons--experience of a Polish center

INTRODUCTION

Kidney transplantation is efficacious as a renal replacement, particularly pre-emptive living donation. In Poland, the rate of transplantation of living donor kidneys is only 3%. The aim of the study was to identify the most common reasons to disqualify a potential living kidney donor.

METHODS

We evaluated 124 kidney donor candidates for 111 potential recipients at 1 medical center for genders and ages of donor and recipient; thus relation, donor disqualification reasons, number of potential donors for a particular recipient, prior transplantations, and kidney vasculature.

RESULTS

The 111 recipients of ages 2-62 years had, 1, 2, or 3 potential donors were tested in 101, 1, and 7, cases respectively. We had 18.9% recipients referred for pre-emptive transplantation; 59.5% were on haemodialysis and 21.6% on peritoneal dialysis. In all, 89% recipients sought first kidney transplantations. Kidneys were procured from 49/124 (39.5%) of the initially evaluated donors. The full examination was completed by 92 potential donors with 68/124 donors disqualified early. Single and multiple renal arteries were detected in 56 and 36 potential donors, respectively. Donor disqualification was due to medical contraindications (39.7%), earlier transplantation from a deceased donor (25%), immunologic constraints (23.5%), donor consent withdrawn (6%) or psychological and social reasons (4.4%).

CONCLUSIONS

A considerable number of donor candidates are disqualified for medical reasons.

Functional insights into recombinant TROSPA protein from Ixodes ricinus

Lyme disease (also called borreliosis) is a prevalent chronic disease transmitted by ticks and caused by Borrelia burgdorferi s. l. spirochete. At least one tick protein, namely TROSPA from I. scapularis, commonly occurring in the USA, was shown to be required for colonization of the vector by bacteria. Located in the tick gut, TROSPA interacts with the spirochete outer surface protein A (OspA) and initiates the tick colonization. Ixodes ricinus is a primary vector involved in B. burgdorferi s. l. transmission in most European countries. In this study, we characterized the capacities of recombinant TROSPA protein from I. ricinus to interact with OspA from different Borrelia species and to induce an immune response in animals. We also showed that the N-terminal part of TROSPA (a putative transmembrane domain) is not involved in the interaction with OspA and that reduction of the total negative charge on the TROSPA protein impaired TROSPA-OspA binding. In general, the data presented in this paper indicate that recombinant TROSPA protein retains the capacity to form a complex with OspA and induces a significant level of IgG in orally immunized rats. Thus, I. ricinus TROSPA may be considered a good candidate component for an animal vaccine against Borrelia.

Low recombination activity of R region located at both ends of the HIV-1 genome

Although two strand transfer events are indispensable for the synthesis of double-stranded DNA and establishing HIV-1 infection, the molecular basis of these phenomena is still unclear. The first obligatory template switching event occurs just at the beginning of the virus replication cycle and involves two copies of the 97-nucleotide long R region, located one each at the both ends of the HIV-1 genome (HIV-1 R). Thus, one can expect that the molecular mechanism of this process is similar to the mechanism of homologous recombination which operates in RNA viruses. To verify the above-mentioned hypothesis, we attempted to assess the recombination activity of HIV-1 R. To this end, we tested in vitro, how effectively it induces template switching by HIV-1 RT in comparison with another well-characterized sequence supporting frequent homologous crossovers in an unrelated virus (R region derived from Brome mosaic virus--BMV R). We also examined if the RNA sequences neighboring HIV-1 R influence its recombination activity. Finally, we tested if HIV-1 R could cause BMV polymerase complex to switch between RNA templates in vivo. Overall, our results have revealed a relatively low recombination activity of HIV-1 R as compared to BMV R. This observation suggests that different factors modulate the efficiency of the first obligatory strand transfer in HIV-1 and the homology-driven recombination in RNA viruses.

Low recombination activity of R region located at both ends of the HIV-1 genome

Although two strand transfer events are indispensable for the synthesis of double-stranded DNA and establishing HIV-1 infection, the molecular basis of these phenomena is still unclear. The first obligatory template switching event occurs just at the beginning of the virus replication cycle and involves two copies of the 97-nucleotide long R region, located one each at the both ends of the HIV-1 genome (HIV-1 R). Thus, one can expect that the molecular mechanism of this process is similar to the mechanism of homologous recombination which operates in RNA viruses. To verify the above-mentioned hypothesis, we attempted to assess the recombination activity of HIV-1 R. To this end, we tested in vitro, how effectively it induces template switching by HIV-1 RT in comparison with another well-characterized sequence supporting frequent homologous crossovers in an unrelated virus (R region derived from Brome mosaic virus--BMV R). We also examined if the RNA sequences neighboring HIV-1 R influence its recombination activity. Finally, we tested if HIV-1 R could cause BMV polymerase complex to switch between RNA templates in vivo. Overall, our results have revealed a relatively low recombination activity of HIV-1 R as compared to BMV R. This observation suggests that different factors modulate the efficiency of the first obligatory strand transfer in HIV-1 and the homology-driven recombination in RNA viruses.

RNA-RNA recombination in plant virus replication and evolution

RNA-RNA recombination is one of the strongest forces shaping the genomes of plant RNA viruses. The detection of recombination is a challenging task that prompted the development of both in vitro and in vivo experimental systems. In the divided genome of Brome mosaic virus system, both inter- and intrasegmental crossovers are described. Other systems utilize satellite or defective interfering RNAs (DI-RNAs) of Turnip crinkle virus, Tomato bushy stunt virus, Cucumber necrosis virus, and Potato virus X. These assays identified the mechanistic details of the recombination process, revealing the role of RNA structure and proteins in the replicase-mediated copy-choice mechanism. In copy choice, the polymerase and the nascent RNA chain from which it is synthesized switch from one RNA template to another. RNA recombination was found to mediate the rearrangement of viral genes, the repair of deleterious mutations, and the acquisition of nonself sequences influencing the phylogenetics of viral taxa. The evidence for recombination, not only between related viruses but also among distantly related viruses, and even with host RNAs, suggests that plant viruses unabashedly test recombination with any genetic material at hand.

Safety and tolerance of sodium mycophenolate in patients after renal transplantation--an observational study

BACKGROUND

Enteric-coated mycophenolate sodium (EC-MPS) was developed as an alternative agent to mycophenolate mofetil (MMF), aimed at reduction of gastrointestinal (GI) complications.

METHODS

Seventy-four patients (mean age 42.3 years) switched from MMF to MPS were included in the study and followed-up for 3 months (Visit 0, Visit 2 after 1 month and Visit 3 after 3 months). The mean time from transplantation to switch was 3.7 years. During Visit 2 and 3 the following were recorded: impact of treatment change on the severity of GI symptoms (4 point scale: 1-worsening, 2-no change, 3-improvement, 4-resolution), EC-MPS tolerance, adverse events (AEs), patient compliance and physician satisfaction with treatment (4 point scale: 1-bad, 2-fair, 3-good, 4-very good).

RESULTS

Sixty-three patients completed the study (85.1%). EC-MPS dose ranged from 720 to 1440 mg. GI symptom severity score averaged at 3.41. Symptoms most commonly compelling a conversion were: abdominal pain, diarrhea, abdominal colic, nausea, anorexia and vomiting. Out of 175 complaints, 144 (82%) either improved or resolved, 5 (2.86%) aggravated, and 25 (14.86%) persisted. Patient compliance and mean physician satisfaction score averaged at 3.70 and 3.02 at Visit 3, respectively. 9 AEs (2 severe) were reported. Causal relationship with the medication was suspected in 5 cases (1 case of SAE). The most common AEs were: anemia, infection (including sepsis), GI symptoms (abdominal pain, diarrhea).

CONCLUSIONS

The following was concluded in our study: (1) sodium mycophenolate is well tolerated; (2) after switching from MMF to EC-MPS, gastrointestinal symptoms alleviated; (3) EC-MPS is a safe medication, with a low adverse events rate.

Characterization of a novel 5' subgenomic RNA3a derived from RNA3 of Brome mosaic bromovirus

The synthesis of 3' subgenomic RNA4 (sgRNA4) by initiation from an internal sg promoter in the RNA3 segment was first described for Brome mosaic bromovirus (BMV), a model tripartite positive-sense RNA virus (W. A. Miller, T. W. Dreher, and T. C. Hall, Nature 313:68-70, 1985). In this work, we describe a novel 5' sgRNA of BMV (sgRNA3a) that we propose arises by premature internal termination and that encapsidates in BMV virions. Cloning and sequencing revealed that, unlike any other BMV RNA segment, sgRNA3a carries a 3' oligo(A) tail, in which respect it resembles cellular mRNAs. Indeed, both the accumulation of sgRNA3a in polysomes and the synthesis of movement protein 3a in in vitro systems suggest active functions of sgRNA3a during protein synthesis. Moreover, when copied in the BMV replicase in vitro reaction, the minus-strand RNA3 template generated the sgRNA3a product, likely by premature termination at the minus-strand oligo(U) tract. Deletion of the oligo(A) tract in BMV RNA3 inhibited synthesis of sgRNA3a during infection. We propose a model in which the synthesis of RNA3 is terminated prematurely near the sg promoter. The discovery of 5' sgRNA3a sheds new light on strategies viruses can use to separate replication from the translation functions of their genomic RNAs.

The weight of pharmacokinetic parameters for mycophenolic acid in prediction of rejection outcome: the receiver operating characteristic curve analysis

Often the clinical researcher is confronted with the question of how accurate a particular laboratory test is to identify disease. To confirm the ability of pharmacokinetic (PK) parameters to discriminate between patients with or without acute rejection after kidney transplantation, an analysis of receiver operating characteristic (ROC) curves was performed in 51 adult patients, among whom nearly 50% experienced biopsy-proven acute rejection episodes during the first 90 days posttransplant. All patients received cyclosporine or tacrolimus, prednisone, and mycophenolate mofetil (MMF). The following PK variables were determined for mycophenolic acid, an active metabolite of MMF: predose (C(0)), maximum concentration (C(max)), and area under the concentration-time curve (AUC(0-12h)). ROC plots of sensitivity versus 1-specificity were generated to determine whether a particular PK parameter could discriminate renal transplant recipients with an acute rejection from those who experienced no rejection. Area under the ROC curves and the 95% confidence interval limits were calculated using the method of Hanley and McNeil. The C(0) and C(max) were less predictive values for acute rejection than AUC(0-12h). The AUC parameter appeared the most effective to discriminate an acute rejection episode during MMF therapy. This study indicated the utility of ROC curve analysis to select PK parameters to predict acute rejection episodes.

Comparison of mycophenolic acid pharmacokinetic parameters in kidney transplant patients within the first 3 months post-transplant

OBJECTIVE

The aim of this study was to investigate the effect of time on pharmacokinetic (PK) parameters of mycophenolic acid (MPA) in the early post-transplant period in kidney recipients. MPA is the active metabolite of mycophenolate mofetil (MMF), which was introduced into clinical practice ten years ago.

METHOD

Mycophenolate mofetil was co-administered with cyclosporin (CsA) in a subgroup of 23 patients and with tacrolimus (Tac) in a subgroup of 10 patients. MPA plasma concentration profiles were measured by a validated high performance liquid chromatography method 1 week, 2 and 3 months after transplantation.

RESULTS

Despite a comparable MMF dose, a large inter-patient variability in both MPA area under the curve (AUC) from 0 to 12 h (range 10.03-135.4 microg h/mL) and in predose concentrations (0.31-6.09 microg/mL) was observed. Patients with AUC > 35 microg h/mL showed better (P < 0.1) renal function than patients with AUC < 20 microg h/mL (mean creatinine concentration 1.48 +/- 0.12 vs. 3.35 +/- 0.4 mg/dL respectively). The total MPA trough and AUC did not correlate with biochemical parameters: leucocyte cell count and haematocrit. A higher trough level of the metabolite MPA glucuronide (MPAG) in the 1 week after transplantation was found when compared with the 3-month level (mean 150.1 +/- 146.7; range 17.1 to 560 vs. 75.8 +/- 40.0; range 27.3 to 174.2 microg/mL). The concentration of MPA, and MPA AUC values were significantly lower in patients receiving MMF and CsA than those receiving MMF and Tac during all three periods studied (P < 0.02). The influence of C(0) and MPA AUC values on the risk of graft rejection was investigated using receiver operating characteristic (ROC) curve analysis. The area under the ROC curve for AUC was 0.847, whereas that of C(0) was 0.632.

CONCLUSIONS

The MPA AUC(0-12h) appeared to be the more effective PK parameter for predicting acute rejection. We recommend that routine MPA and MPAG therapeutic drug level monitoring should be an important part of MMF therapy.

Serum TGF-beta1 correlates with chronic histopathological lesions in protocol biopsies of kidney allograft recipients

INTRODUCTION

Transforming growth factor-beta (TGF-beta) is a well-known profibrotic factor playing a role in chronic kidney allograft nephropathy. Cyclosporine (CsA)-sparing immunosuppressive regimens may improve long-term graft function. Our aim was to study the influence of immunosuppressive treatment with versus without calcineurin inhibitors on serum TGF-beta levels and histological changes in protocol biopsies of kidney allograft recipients.

PATIENTS AND METHODS

In this prospective, randomized study of 42 low-rejection risk patients we randomized two groups: group A: mycophenolate mofetil (MMF), prednisone, daclizumab, and reduced CsA dose for 7 months (5 mg per kg per day) followed by complete withdrawal (n = 21); and group B: normal CsA dose (10 mg per kg per day adjusted according to C2 levels), MMF, prednisone, and no daclizumab (n = 21).

METHODS

In both groups we performed histological assessments (Banff 97) and measured serum TFG-beta levels before as well as, at 3 and 12 months after transplantation.

RESULTS

We found a relationship between immunosuppressive regimen and the TGF-beta concentration over 1 year of observation. Before transplant the TGF-beta1 levels did not differ between the groups (P = .29); at 3 months they were 33 +/- 9 vs 49 +/- 15 pg per mL, respectively, in groups A and B (P = .08), and at 12 months they were 39.5 +/- 4 versus 55.5 +/- 11 pg per mL, respectively, in groups A and B (P = .03). Protocol biopsies at 12 months in group B showed chronic tubular lesions more pronounced than in group A. TGF-beta1 concentrations were significantly higher among group B than A. We conclude that TGF-beta1 concentration may predict the development of kidney graft fibrosis; early CsA withdrawal may achieve a reduction in chronic tubular and interstitial injury of cadaveric kidney allografts.

A universal BMV-based RNA recombination system--how to search for general rules in RNA recombination

At present, there is no doubt that RNA recombination is one of the major factors responsible for the generation of new RNA viruses and retroviruses. Numerous experimental systems have been created to investigate this complex phenomenon. Consequently, specific RNA structural motifs mediating recombination have been identified in several viruses. Unfortunately, up till now a unified model of genetic RNA recombination has not been formulated, mainly due to difficulties with the direct comparison of data obtained for different RNA-based viruses. To solve this problem, we have attempted to construct a universal system in which the recombination activity of various RNA sequences could be tested. To this end, we have used brome mosaic virus, a model (+)RNA virus of plants, for which the structural requirements of RNA recombination are well defined. The effectiveness of the new homomolecular system has been proven in an experiment involving two RNA sequences derived from the hepatitis C virus genome. In addition, comparison of the data obtained with the homomolecular system with those generated earlier using the heteromolecular one has provided new evidence that the mechanisms of homologous and non-homologous recombination are different and depend on the virus' mode of replication.

Two types of non-homologous RNA recombination in brome mosaic virus

Non-homologous RNA recombination is a process enabling the exchange of genetic material between various (related or unrelated) RNA-based viruses. Despite extensive investigations its molecular mechanism remains unclear. Studies on genetic recombination in brome mosaic virus (BMV) have shown that local hybridization between genomic RNAs induces frequent non-homologous crossovers. A detailed analysis of recombinant structures suggested that local complementary regions might be involved in two types of non-homologous recombination in BMV: site-specific and heteroduplex-mediated. To verify the above hypothesis and better recognize the mechanism of the phenomenon studied we have tested how the putative types of recombination are affected by a specific mutation in the BMV polymerase gene or by changes in RNA structure. The experiments undertaken revealed substantial differences between site-specific and heteroduplex-mediated recombination, indicating that they occur according to different mechanisms. The former can be classified as homology-assisted, and the latter as homology-independent. In addition to local RNA/RNA hybridization, short regions of homology are required for site-specific crossovers to occur. They are most efficiently mediated if one homologous sequence is located at the beginning of and the second just before a double-stranded region. At present it is difficult to state what is the mechanism of heteroduplex-mediated recombination. Earlier it was postulated that strong RNA/RNA interaction enforces template switching by the viral replicase. There are, however, several observations questioning this model and indicating that some other factors, which are still unknown, may influence heteroduplex-mediated crossovers.

Homologous crossovers among molecules of brome mosaic bromovirus RNA1 or RNA2 segments in vivo

Previously we demonstrated frequent homologous crossovers among molecules of the RNA3 segment in the tripartite brome mosaic bromovirus (BMV) RNA genome (A. Bruyere, M. Wantroba, S. Flasinski, A. Dzianott, and J. J. Bujarski, J. Virol. 74:4214-4219, 2000). To further our knowledge about mechanisms of viral RNA genome variability, in this paper we have studied homologous recombination in BMV RNA1 and RNA2 components during infection. We have found that basal RNA-RNA crossovers could occur within coding regions of both RNAs, although recombination frequencies slightly varied at different RNA sections. In all cases, the frequencies were much lower than the rate observed for the intercistronic recombination hot spot in BMV RNA3. Probability calculations accounted for at least one homologous crossover per RNA molecule per replication cycle. In addition, we have demonstrated an efficient repair of mutations within the conserved 3' and 5' noncoding regions, most likely due to error-prone BMV RNA replication. Overall, our data verify that homologous crossovers are common events a during virus life cycle, and we discuss their importance for viral RNA genetics.