Engaging patients in designing a transmural allied health pathway: A qualitative exploration of hospital-to-home transitions

INTRODUCTION

The transition from hospital to home is often suboptimal, resulting in patients not receiving the necessary allied healthcare after discharge. This may, in turn, lead to delayed recovery, a higher number of readmissions, more emergency department visits and an increase in mortality and healthcare costs. This study aimed to gain insight into patients' experiences, perceptions, and needs regarding hospital-to-home transition, focusing on allied healthcare as a first step towards the development of a transitional integrated allied healthcare pathway for patients with complex care needs after hospital discharge.

METHODS

We conducted semistructured interviews with patients. Participants were recruited from universities and general hospitals in the Amsterdam region between May and July 2023. They were eligible if they (1) were discharged from the hospital minimally 3 and maximally 12 months after admission to an oncologic surgery department, internal medicine department, intensive care unit, or trauma centre, (2) received hospital-based care from at least one allied healthcare provider, who visited the patient at least twice during hospital admission, (3) spoke Dutch or English and (4) were 18 years or older. Interviews were audio-recorded and transcribed verbatim. We performed a thematic analysis of the interview data.

RESULTS

Nineteen patients were interviewed. Three themes emerged from the analysis. 'Allied healthcare support during transition' depicts patients' positive experiences when they felt supported by allied health professionals during the hospital-to-home transition. 'Patient and family involvement' illustrates how much patients value the involvement of their family members during discharge planning. 'Information recall and processing' portrays the challenges of understanding and remembering overwhelming amounts of information, sometimes unclear and provided at the wrong moment. Overall, patients' experiences of transitional care were positive when they were involved in the discharge process. Negative experiences occurred when their preferences for postdischarge communication were ignored.

CONCLUSIONS

This study suggests that allied health professionals need to continuously collaborate and communicate with each other to provide patients and their families with the personalized support they need. To provide high-quality and person-centred care, it is essential to consider how, when, and what information to provide to patients and their families to allow them to contribute to their recovery actively.

PATIENT OR PUBLIC CONTRIBUTION

The interview guide for this manuscript was developed with the assistance of patients, who reviewed it and provided us with feedback. Furthermore, patients provided us with their valuable lived experiences by participating in the interviews conducted for this study.

Inspiratory muscle training for mechanically ventilated patients in the intensive care unit: Obstacles and facilitators for implementation. A mixed method quality improvement study

BACKGROUND

Mechanically ventilated patients are at risk of developing inspiratory muscle weakness (IMW), which is associated with failure to wean and poor outcomes. Inspiratory muscle training (IMT) is a recommended intervention during and after extubation but has not been widely adopted in Dutch intensive care units (ICUs).

OBJECTIVES

The objective of this study was to explore the potential, barriers, and facilitators for implementing IMT as treatment modality for mechanically ventilated patients.

METHODS

This mixed-method, proof-of-concept study was conducted in a large academic hospital in the Netherlands. An evidence-based protocol for assessing IMW and training was applied to patients ventilated for ≥24 h in the ICU during an 8-month period in 2021. Quantitative data on completed measurements and interventions during and after ICU-stay were collected retrospectively and were analysed descriptively. Qualitative data were collected through semistructured interviews with physiotherapists executing the new protocol. Interview data were transcribed and thematically analysed.

FINDINGS

Of the 301 screened patients, 11.6% (n = 35) met the inclusion criteria. Measurements were possible in 94.3% of the participants, and IMW was found in 78.8% of the participants. Ninety-six percent started training in the ICU, and 88.5% continued training after transfer to the ward. Follow-up measurements were achieved in 73.1% of the patients with respiratory muscle weakness. Twelve therapists were interviewed, of whom 41.7% regularly worked in the ICU. When exploring reasons for protocol deviation, three themes emerged: "professional barriers", "external factors", and "patient barriers".

CONCLUSIONS

Implementation of measurements of and interventions for IMW showed to be challenging in this single centre study. Clinicians' willingness to change their handling was related to beliefs regarding usefulness, effectiveness, and availability of time and material. We recommend that hospitals aiming to implement IMT during or after ventilator weaning consider these professional and organisational barriers for implementation of novel, evidence-based interventions into daily clinical practice.

Telerehabilitation Delivery in Canada and the Netherlands: Results of a Survey Study

BACKGROUND

Following the onset of the COVID-19 pandemic, telerehabilitation (TR) has been expanding to address the challenges and risks of in-person delivery. It is likely that a level of TR delivery will continue after the pandemic because of its advantages, such as reducing geographical barriers to service. Many pandemic-related TR initiatives were put in place quickly. Therefore, we have little understanding of current TR delivery, barriers and facilitators, and how therapists anticipate integrating TR into current practice. Knowing this information will allow the incorporation of competencies specifically related to the use and provision of TR into professional profiles and entry-to-practice education, thereby promoting high-quality TR care.

OBJECTIVE

This study aimed to obtain a descriptive overview of current TR practice among rehabilitation therapists in Canada and the Netherlands and identify perceived barriers to and facilitators of practice.

METHODS

A web-based cross-sectional survey was conducted with occupational, physical, and respiratory therapists and dietitians in Canada (in French and English) and the Netherlands (in Dutch and English) between November 2021 and March 2022. Recruitment was conducted through advertisements on social media platforms and email invitations facilitated by regulatory and professional bodies. The survey included demographic and practice setting information; whether respondents delivered TR, and if so, components of delivery; confidence and satisfaction ratings with delivery; and barriers to and facilitators of use. TR satisfaction and uptake were measured using the Telehealth Usability Questionnaire and modified Technology Acceptance Model. Data were first summarized descriptively, and then, comparisons were conducted between professions.

RESULTS

Overall, 723 survey responses were received, mostly from Canada (n=666, 92.1%) and occupational therapists (n=434, 60%). Only 28.1% (203/723) reported receiving specific training in TR, with 1.2% (9/723) indicating that it was part of their professional education. Approximately 19.5% (139/712) reported not using TR at all, whereas most participants (366/712, 51.4%) had been using this approach for 1 to 2 years. Services delivered were primarily teleconsultation and teletreatment with individuals. Respondents offering TR were moderately satisfied with their service delivery and found it to be effective; 90.1% (498/553) indicated that they were likely to continue offering TR after the pandemic. Technology access, confidence, and setup were rated the highest as facilitators, whereas technology issues and the clinical need for physical contact were the most common barriers.

CONCLUSIONS

Professional practice and experience with TR were similar in both countries, suggesting the potential for common strategic approaches. The high prevalence of current practice and strong indicators of TR uptake suggest that therapists are likely to continue TR delivery after the pandemic; however, most therapists (461/712, 64.7%) felt ill prepared for practice, and the need to target TR competencies during professional and postprofessional education is critical. Future studies should explore best practice for preparatory and continuing education.

Recommendations for an exercise intervention and core outcome set for older patients after hospital discharge: Results of an international Delphi study

For older adults, acute hospitalization is a high-risk event with poor health outcomes, including functional decline. In absence of practical guidelines and high quality randomized controlled trials, this Delphi study was conducted. The aim of this study was to obtain consensus on an exercise intervention program, a core outcome set (COS) and handover information to prevent functional decline or restore physical function in acutely hospitalized older patients transitioning from hospital to home. An internal panel of experts in the field of exercise interventions for acutely hospitalized older adults were invited to join the study. In the Delphi study, relevant topics were recognized, statements were formulated and ranked on a 9-point Likert scale in two additional rounds. To reaching consensus, a score of 7-9 was classified as essential. Results were expressed as median and semi-interquartile range (SIQR), and consensus threshold was set at SIQR≤0.5. Fifteen international experts from eight countries participated in the panel. The response rate was 93%, 93% and 80% for the three rounds respectively. After three rounds, consensus was reached on 167 of the 185 (90.3%) statements, of which ninety-five (51.4%) were ranked as essential (median Likert-score ≥7.0, SIQR ≤0.5). This Delphi study provides starting points for developing an exercise intervention, a COS and handover information. The results of this Delphi study can assist physical therapists to provide a tailored exercise intervention for older patients with complex care needs after hospital discharge, to prevent functional decline and/or restore physical function.

Prevention of musculoskeletal disorders among animal research technicians: Understanding difficulties and their determinants through a work activity analysis

This study aimed at understanding animal research technicians (ART) work activity to identify difficulties encountered by workers and their determinants which may increase musculoskeletal disorders (MSD) risks. The methods for the work activity analysis combined interviews, observations, events and operations chronicles as well as inclinometry. From the work activity analysis of the three main tasks (changing mouse cages, preparation of water bottles and unloading dirty material), difficulties such as awkward postures, heavy load handling, repetitiveness, high workload, supplementary tasks, interruptions and difficult social interactions emerged. The work activity analysis further allowed the identification of determinants of these difficulties. Some are related to the physical, organizational or social work environment, and others to the interdependence between these determinants. Such an improved understanding of ART work activity will lead to solutions best suited for MSDs prevention in this understudied setting.

Feasibility of a home-based interdisciplinary rehabilitation program for patients with Post-Intensive Care Syndrome: the REACH study

BACKGROUND

Survivors of critical illness experience long-term functional challenges, which are complex, heterogeneous, and multifactorial in nature. Although the importance of rehabilitation interventions after intensive care unit (ICU) discharge is universally recognized, evidence on feasibility and effectiveness of home-based rehabilitation programs is scarce and ambiguous. This study investigates the feasibility of an interdisciplinary rehabilitation program designed for patients with Post-Intensive Care Syndrome (PICS) who are discharged home.

METHODS

A mixed method, non-randomized, prospective pilot feasibility study was performed with a 6-month follow-up, comparing the intervention (REACH) with usual care. REACH was provided by trained professionals and included a patient-centered, interdisciplinary approach starting directly after hospital discharge. Primary outcomes were patient safety, satisfaction, adherence, referral need and health care usage. Secondary outcomes, measured at 3 timepoints, were functional exercise capacity, self-perceived health status, health-related quality of life (HRQoL), return to work and psychotrauma. Risk of undernutrition was assessed at baseline.

RESULTS

43 patients with a median mechanical ventilation duration of 8 (IQR:10) days, were included in the study and 79.1% completed 6-month follow-up. 19 patients received the intervention, 23 received usual care. Groups were similar for gender distribution and ICU length of stay. No adverse events occurred. REACH participants showed higher satisfaction with treatment and reported more allied health professional visits, while the usual care group reported more visits to medical specialists. Qualitative analysis identified positive experiences among REACH-professionals related to providing state-of-the-art interventions and sharing knowledge and expertise within an interprofessional network. Similar recovery was seen between groups on all secondary outcomes, but neither group reached reference values for HRQoL at 6 months. Larger return to work rates were seen in the REACH group. Prevalence of undernutrition at hospital discharge was high in both groups (> 80%), warranting the need for careful tuning of physical therapy and nutritional interventions.

CONCLUSIONS

This study shows that providing early, home-based rehabilitation interventions for patients with PICS-related symptoms is feasible and perceived positively by patients and professionals. When provided in an interdisciplinary collaborative network state of the art, person-centered interventions can be tailored to individual needs potentially increasing patient satisfaction, adherence, and efficacy. Registered in the Dutch Trial register: NL7792: https://www.trialregister.nl/trial/7792 , registered 7-06-2019.

Preparing undergraduate students for clinical work in a complex environment: evaluation of an e-learning module on physiotherapy in the intensive care unit

BACKGROUND

Intensive Care Units (ICUs) are daunting environments for physiotherapy (PT) students performing clinical rotations. To prepare students for this environment, a newly developed, evidence-based e-learning module was designed and implemented in the undergraduate curriculum. The aim of this study was to investigate whether e-learning is a feasible method in preparing PT students for clinical work in complex ICU environments, as perceived by students and experts.

METHODS

A mixed methods proof of concept study was undertaken. Participants were final-year students of an international curriculum, and experts from didactic and clinical fields. An e-learning module consisting of 7 separate chapters based on the latest scientific evidence and clinical expertise was developed, piloted and incorporated into the undergraduate curriculum as a compulsory course to be completed prior to clinical ICU rotations. Data were collected through 3 focus group meetings and 5 semi-structured interviews; these meetings and interviews were audio recorded, transcribed verbatim and analyzed.

RESULTS

The study sample comprised of 14 students and 5 experts. Thematic analysis revealed three themes: expected competencies of PT students in ICU, feeling prepared for ICU clinical work and dealing with local variety. The e-learning module enabled students to anticipate clinical situations and PT tasks in the ICU. Higher level clinical reasoning skills, handling of lines and wires and dealing with out-of-textbook situations could not be achieved with the e-learning module alone.

CONCLUSIONS

An e-learning module can sufficiently prepare PT students for their clinical tasks in the ICU, as long as it is integrated with, or closely connected to, the students' clinical placement.

Physiotherapy treatment approaches for survivors of critical illness: a proposal from a Delphi study

Purpose: The aim of this study was to develop practical recommendations for physiotherapy for survivors of critical illness after hospital discharge. Methods: A modified Delphi consensus study was performed. A scoping literature review formed the basis for three Delphi rounds. The first round was used to gather input from the panel to finalize the survey for the next two rounds in which the panel was asked to rank each of the statements on an ordinal scale with the objective to reach consensus. Consensus was defined as a SIQR of ≤ 0.5. Ten Dutch panelists participated in this study: three primary care physiotherapists, four intensive care physiotherapists, one occupational therapist, one ICU-nurse and one former ICU-patient. All involved professionals have treated survivors of critical illness. Our study was performed in parallel with an international Delphi study with hospital-based health-care professionals and researchers. Results: After three Delphi rounds, consensus was reached on 95.5% of the statements. This resulted in practical recommendations for physiotherapy for critical illness survivors in the primary care setting. The panel agreed that the handover should include information on 14 items. Physiotherapy treatment goals should be directed toward improvement of aerobic capacity, physical functioning, activities in daily living, muscle strength, respiratory and pulmonary function, fatigue, pain, and health-related quality of life. Physiotherapy measurements and interventions to improve these outcomes are suggested. Conclusion: This study adds to the knowledge on post-ICU physiotherapy with practical recommendations supporting clinical decision-making in the treatment of survivors of critical illness after hospital discharge.

Clearance of hepatitis C in chimpanzees is associated with intrahepatic T-cell perforin expression during the late acute phase

The liver is the primary site of hepatitis C virus (HCV) replication. Therefore, we undertook detailed intrahepatic studies of T-cell dynamics, apoptosis, and gene expression during the acute phase of infection using liver biopsies from chimpanzees that developed persistent infection or spontaneously cleared the virus. We examined more than 40 liver biopsies histologically and quantitatively for T-cell infiltration, hepatocyte apoptosis and perforin expression. These data were correlated with outcome and viral kinetics. We observed intrahepatic T-cell infiltration in both groups of animals with CD8(+) T cells representing the major population. The appearance of T cells was always associated with apoptosis and mild alanine aminotransferase (ALT) elevations. Apoptosis (5-20% of hepatocytes) always occurred prior to serum ALT peak. Quantification of intrahepatic ALT mRNA revealed no upregulation of gene expression confirming that serum ALT increases were due to release of this enzyme from cells. During the late acute phase, cleared animals showed an increased frequency of hepatocyte apoptosis relative to persistently infected animals (P < 0.05). This correlated with a higher intrahepatic CD8(+) T-cell frequency in the cleared group (P < 0.01) with a greater proportion of lymphocytes expressing perforin compared with the persistent group (P < 0.001). All infected animals mounted intrahepatic immune responses during the acute phase, but these were not maintained in frequency or efficacy in persistent infections. There is a reduction in the numbers of intrahepatic T cells during the late acute phase in infections that become persistent with significantly fewer of these cells functional in clearing the virus by killing infected hepatocytes.

T-cell vaccines that elicit effective immune responses against HCV in chimpanzees may create greater immune pressure for viral mutation

A prime/boost vaccine strategy that transfects antigen-presenting cells using ligand-modified immunoliposomes to efficiently deliver plasmid DNA, followed by boosting with non-replicating recombinant adenovirus was used in chimpanzees to generate HCV-specific memory T-cells. Three chimpanzees (two vaccines, one control) were immunized with immunoliposomes complexed with DNA expressing NS3-NS5B or complexed with empty vector. Animals were boosted with adenovirus expressing NS3-NS5B, or non-recombinant adenovirus (control). Using liposome delivery we were able to obtain specific HCV responses following DNA priming in the chimpanzees. This data and mouse immunization studies confirm this as a more efficient delivery system than direct intramuscular inoculations with naked DNA. Subsequent to the adenovirus boost significant increases in peripheral HCV-specific T-cell responses and intrahepatic IFN-gamma and CD3varepsilon mRNA were also observed in the two vaccinated animals. Following challenge (100 CID(50)) both vaccinated animals showed immediate and significant control of viral replication (peak titers 3.7x10(4) and 9x10(3)IU/mL at weeks 1 and 2), which coincided with increases in HCV-specific T-cell responses. Viral kinetics in the control animal were comparable to historical controls with exponential increases in titer during the first several weeks. One vaccinated animal developed a low-level persistent infection (2x10(3)IU/mL) which correlated with a decrease in HCV-specific T-cell responses. Circulating virus isolated from both vaccinated animals showed approximately 2-fold greater nonsynonymous mutation rates compared to controls and the nonsynonymous/synonymous mutation rate ratio was indicative of positive selection. These data suggest that although T-cell vaccines can induce immune responses capable of controlling HCV, they also induce high levels of immune pressure for the potential selection of escape mutants.

Neutralizing antibody response during acute and chronic hepatitis C virus infection

Little is known about the role of Abs in determining the outcome of hepatitis C virus (HCV) infection. By using infectious retroviral pseudotypes bearing HCV glycoproteins, we measured neutralizing Ab (nAb) responses during acute and chronic HCV infection. In seven acutely infected health care workers, only two developed a nAb response that failed to associate with viral clearance. In contrast, the majority of chronically infected patients had nAbs. To determine the kinetics of strain-specific and crossreactive nAb emergence, we studied patient H, the source of the prototype genotype 1a H77 HCV strain. An early weak nAb response, specific for the autologous virus, was detected at seroconversion. However, neutralization of heterologous viruses was detected only between 33 and 111 weeks of infection. We also examined the development of nAbs in 10 chimpanzees infected with H77 clonal virus. No nAb responses were detected in three animals that cleared virus, whereas strain-specific nAbs were detected in six of the seven chronically infected animals after approximately 50 weeks of infection. The delayed appearance of high titer crossreactive nAbs in chronically infected patients suggests that selective mechanism(s) may operate to prevent the appearance of these Abs during acute infection. The long-term persistence of these nAbs in chronically infected patients may regulate viral replication.

Prophylactic DNA vaccine for hepatitis C virus (HCV) infection: HCV-specific cytotoxic T lymphocyte induction and protection from HCV-recombinant vaccinia infection in an HLA-A2.1 transgenic mouse model

DNA vaccines express antigens intracellularly and effectively induce cellular immune responses. Because only chimpanzees can be used to model human hepatitis C virus (HCV) infections, we developed a small-animal model using HLA-A2.1-transgenic mice to test induction of HLA-A2.1-restricted cytotoxic T lymphocytes (CTLs) and protection against recombinant vaccinia expressing HCV-core. A plasmid encoding the HCV-core antigen induced CD8(+) CTLs specific for three conserved endogenously expressed core peptides presented by human HLA-A2.1. When challenged, DNA-immunized mice showed a substantial (5-12 log(10)) reduction in vaccinia virus titer compared with mock-immunized controls. This protection, lasting at least 14 mo, was shown to be mediated by CD8(+) cells. Thus, a DNA vaccine expressing HCV-core is a potential candidate for a prophylactic vaccine for HLA-A2.1(+) humans.

Long-term follow-up of chimpanzees inoculated with the first infectious clone for hepatitis C virus

Two chimpanzees (Ch1535 and Ch1536) became infected with hepatitis C virus (HCV) following intrahepatic inoculation with RNA transcribed from a full-length cDNA clone of the virus. Both animals were persistently infected and have been followed for 60 weeks. They showed similar responses to infection, with transient liver enzyme elevations and liver inflammatory responses, which peaked at weeks 17 (Ch1535) and 12 (Ch1536) postinoculation (p.i.). Antibody responses to structural and nonstructural proteins were first detected at weeks 13 (Ch1535) and 10 (Ch1536) p.i. Serum RNA titers increased steadily during the first 10 to 13 weeks but decreased sharply in both animals following antibody and inflammatory responses. Despite direct evidence of humoral immune responses to multiple viral antigens, including hypervariable region 1 (HVR1), both animals remained chronically infected. Detailed sequence analysis of serum HCV RNA revealed no change in the majority HVR1 sequence in Ch1535 and a single-amino-acid mutation in Ch1536, with very little clonal variation in either animal. Full-length genome analysis at week 60 revealed several amino acid substitutions localized to antigens E1, E2, p7, NS3, and NS5. Of these, 55.6 and 40% were present as the majority sequence in serum RNA isolated at week 26 p.i. (Ch1535) and week 22 p.i. (Ch1536), respectively, and could represent immune escape mutations. Mutations accumulated at a rate of 1.57 x 10(-3) and 1.48 x 10(-3) nucleotide substitutions/site/year for Ch1535 and Ch1536, respectively. Taken together, these data indicate that establishment of a persistent HCV infection in these chimpanzees is not due to changes in HVR1; however, the possibility remains that mutations arising in other parts of the genome contributed to this persistence.

T cell recognition of hypervariable region-1 from hepatitis C virus envelope protein with multiple class II MHC molecules in mice and humans: preferential help for induction of antibodies to the hypervariable region

Hypervariable region-1 (HVR1) from the hepatitis C virus (HCV) envelope protein is thought to be a target for neutralizing Abs. To explore HVR1 recognition by helper T cells, and their role in Ab responses, we attempted to generate helper T cells specific for HVR1 in mice of three MHC types, and with PBMC from HCV-infected HLA-diverse humans. In both species, HVR1 was presented by >1 class II MHC molecule to CD4+ helper T cells and showed surprising interisolate cross-reactivity. The epitope for two DR4+ patients was mapped to a more conserved C-terminal sequence containing a DR4 binding motif, possibly accounting for cross-reactivity. Strikingly, Abs to patients' own HVR1 sequences were found only in patients with T cell responses to HVR1, even though all had Abs to envelope protein, suggesting that induction of Abs to HVR1 depends on helper T cells specific for a sequence proximal to the Ab epitope. Thus, helper T cells specific for HVR1 may be functionally important in inducing neutralizing Abs to HCV. These results may be the first example of "T-B reciprocity," in which proximity of a helper T cell epitope determines Ab epitope specificity, in a human disease setting.

Immune responses against hepatitis C virus structural proteins following genetic immunisation

We have used direct DNA inoculation to study the in vivo induction of both humoral and cellular immune responses to hepatitis C virus (HCV) encoded structural antigens. Following immunisation of mice, immune responses were compared using plasmids encoding full-length or partial HCV gene sequences for the nucleocapsid and envelope E2 proteins. Plasmids encoding secreted or non-secreted forms of the immunogens, including constructs expressing HCV sequences fused with the hepatitis B virus surface antigen (HCV-HBV chimeras), were evaluated. Results indicate that: (i) all constructs induced specific anti-HCV antibodies; (ii) antibody titres ranged from 1:100 to > 1:100,000; (iii) all HCV DNA immunogens induced a predominant Th1 response with the induction of IgG2a antibodies; (iv) the secretion level of the antigens and immune responses was not always correlated and (v) CTL could be detected against both HCV and HBV determinants.

Immunization with plasmid DNA encoding hepatitis C virus envelope E2 antigenic domains induces antibodies whose immune reactivity is linked to the injection mode

Plasmids expressing different domains of the hepatis C virus (HCV) envelope E2 glycoprotein from a genotype 1a isolate were constructed to compare the immunogenic potential of E2 in nucleic acid-based immunizations. One plasmid, pCIE2t, expressed a C-terminally truncated form of E2, while others, pS2.SE2A to pS2.SE2E, encoded the adjacent 60-amino-acid (aa) sequences of E2 (inserts A to E) expressed as a fusion with the hepatitis B virus surface antigen. BALB/c mice were given injections of the plasmids intramuscularly (i.m.) or intraepidermally (i.e.) via a gene gun (biolistic introduction), and induced humoral immune responses were evaluated. The i.e. injections resulted in higher seroconversion rates and antibody titers, up to 100-fold, than did the i.m. injections (P = 0.01 to 0.04). Three restricted immunogenic domains, E2A (aa 384 to 443), E2C (aa 504 to 555), and E2E (aa 609 to 674), that yielded antibody titers ranging from 1:59 to > 1:43,700 could be identified. Subtype 1a- and 1b-derived E2 antigens and synthetic peptides were used in Western blot and enzyme-linked immunosorbent assay analyses, which revealed that the cross-reactivity of the plasmid-induced antibodies was linked both to the type of antigen expressed and to the injection mode. Induced anti-E2 antibodies could immunoprecipitate noncovalent E1E2 complexes believed to exist on the surface of HCV virions. This study allowed us to identify restricted immunogenic domains within E2 and demonstrated that different routes of injection of HCV E2 plasmids can result in quantitatively and qualitatively different humoral immune responses.

DNA vaccination for the induction of immune responses against hepatitis C virus proteins

Recent analysis of clinical and experimental cases of hepatitis C virus (HCV) infection suggest the possible role of the viral nucléocapsid (C), the nonstructural protein 3 (NS3) and the envelope glycoproteins E1 and/or E2 in the mounting of immune responses capable to control infection (Botarelli et al., Gastroenterology, 1993, 104, 580-587; Choo et al., Proc. Natl Acad. Sci. USA, 1994, 91, 1294-1298). We have used DNA-based immunization to study the immune responses that can be induced by injecting DNA-derived immunogens encoding C and E2 sequences. Comparative analysis were performed in mice using expression plasmids containing full-length or partial gene sequences cloned in fusion with the hepatitis B virus surface antigen (HBV-HCV chimeras). The results obtained indicate that: (1) anti-C and anti-E2 antibodies can be induced with all constructs including the HBV-HCV chimeras; (2) titers range from 1:100 to 1:100000 depending on the antigen and nucleotide sequence context; (3) all HCV DNA immunogens are associated with a predominant Th1 response; (4) CTL can be detected against both HCV and HBV determinants.

Plasmid DNA expressing a secreted or a nonsecreted form of hepatitis C virus nucleocapsid: comparative studies of antibody and T-helper responses following genetic immunization

In a murine model, we have compared humoral and T-helper (Th) responses induced following genetic immunization with two hepatitis C virus (HCV) plasmid-derived immunogens: a plasmid expressing the full-length nucleocapsid (CAP) as a nonsecreted antigen (pCMVC2) and a plasmid expressing the amino-terminal part of CAP as a secreted antigen (pS2S.C2N). In BALB/c mice, intramuscular injection of either plasmid induced IgG2a antibodies associated with a Th1-like profile characterized by the in vitro splenic production of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma). The pS2S.C2N plasmid induced antibody titers three- to five-fold higher than those obtained with the pCMVC2 plasmid (maximal titers 1:1,500 versus 1:500). In control experiments, immunization using purified CAP antigen induced a predominant, but not exclusive, Th2-like profile as determined by the splenic production of IL-4 and IL-10. Six putative Th determinants were identified using a panoply of overlapping synthetic peptides in in vitro stimulation assays: amino acids 20-44, 39-63, 79-113, 89-113, 118-142, and 138-152. For all CAP immunogens, MHC haplotype of immunized mice was found to influence seroconversion rates but not the type of cytokines produced in vitro. H-2d mice were faster responders and displayed recall T-cell activation by a larger number of peptides than H-2b mice, whereas H-2s mice were overall very poor responders. Splenic stimulation by at least one determinant, amino acids 79-103, appeared to be highly specific of the H-2b background and of DNA immunization only. These data indicate that DNA immunogens expressing different forms of HCV-CAP are not associated with different Th profiles but rather different seroconversion rates and antibody titers and that collaboration of distinct T-help epitopes can be restricted by the MHC background.

In vitro inhibition of hepatitis C virus gene expression by chemically modified antisense oligodeoxynucleotides

We have explored different domains within the hepatitis C virus (HCV) 5' noncoding region as potential targets for inhibition of HCV translation by antisense oligodeoxynucleotides (ODNs). Inhibition assays were performed with two different cell-free systems, rabbit reticulocyte lysate and wheat germ extract, and three types of chemical structures for the ODNs were evaluated: natural phosphodiesters (beta-PO), alpha-anomer phosphodiesters (alpha-PO), and phosphorothioates (PS). A total of six original ODNs, displaying sequence-specific inhibition ranging from 62 to 96%, that mapped in the pyrimidine-rich tract (nucleotides [nt] 104 to 127) and in the initiator AUG codon (nt 338 to 357) were identified. Two ODNs, which were targeted at the initiatory AUG (nt 341 to 367 and 351 to 377) and which had been previously described as active against genotype 1b and 2a sequences, were shown to exhibit inhibition of expression (> 95%) of a type 1a sequence. Control experiments with the irrelevant chloramphenicol acetyltransferase sequence as a marker and randomized ODNs demonstrated that levels of inhibition associated with the use of PS compounds (of as much as 94%) were mainly due to nonspecific effects. Both alpha- and beta-PO ODNs were found equally active, and no difference could be seen in the activity of beta-PO when it was tested in either rabbit reticulocyte lysate or wheat germ extract, suggesting that RNase H-independent mechanisms may be involved in the inhibitions observed. However, specific RNA cleavage products generated from beta-PO inhibition experiments could be identified, indicating that, with these compounds, control of translation also involves RNase H-dependent mechanisms. This study further delimits the existence of favorable target sequences for the action of ODNs within the HCV 5' noncoding region and indicates the possibility of using nuclease-resistant alpha-PO compounds in cellular studies.

DNA-based immunization with chimeric vectors for the induction of immune responses against the hepatitis C virus nucleocapsid

Vectors expressing the first 58 amino acids of the hepatitis C virus (HCV) nucleocapsid alone or as a fusion protein with the middle (pre-S2 and S) or major (S) surface antigens of hepatitis B virus (HBV) were constructed. Intramuscular immunization of BALB/c mice with the chimeric constructs in the form of naked DNA elicited humoral responses to antigens from both viruses within 2 to 6 weeks postinjection. No anti-HCV responses were obtained in mice immunized with the vector expressing the HCV sequence in the nonfusion context. Sera from chimera-injected mice specifically recognized both HCV capsid and HBV surface antigens in enzyme-linked immunosorbent assay and immunoblot testing. Anti-HCV serum titers formed plateaus of approximately 1:3,000; these remained stable until the end of the study (18 weeks postinfection). Anti-HBV immune responses were found to be lower in the chimera-injected animals (< 200 mIU/ml) than in those immunized with the native HBV vector (> 2,000 mIU/ml). This is the first report of the use of DNA-based immunization for the generation of immune responses to an HCV protein. In addition, these findings show that it is possible to elicit responses to viral epitopes from two distinct viruses via DNA immunization with chimeric vectors.

Complete sequence conservation of the human T cell leukaemia virus type 1 tax gene within a family cluster showing different pathologies

We have amplified, through PCR, the full-length tax gene of human T cell leukaemia virus type 1 (HTLV-1) derived from proviral DNA of peripheral blood lymphocytes of five first degree relatives of Afro-Caribbean origin. One patient (the father) had adult T cell leukaemia (ATL), one (the mother) tropical spastic paraparesis (TSP), and three (children) were healthy asymptomatic carriers. All five family members had identical tax nucleotide sequences as determined by direct sequencing of PCR products. This sequence was compared with tax gene sequences of an unrelated TSP patient of Afro-Caribbean origin, and of C8166 cells, and found to have one and seven nucleotide differences, respectively. At the amino acid level these three sequences differed from the HTLV-1 prototype Japanese strain (ATK-1). All sequence changes were clustered towards the 3' end of the gene. These data demonstrate the complete conservation of an HTLV-1 gene following, presumably, horizontal and vertical transmission of the virus. Clones of this gene showed more sequence variation within the TSP patient than the ATL patient, mostly consisting of point mutations; there was no conservation of mutations between the two individuals. These mutations occurred only in individual clones of the ATL patient whereas those of the TSP patient were found to be repeated in different clones. A tax-specific cytotoxic T lymphocyte response was observed in two asymptomatic carriers with low antibody titres, whereas none was detected in an individual with a high antibody level. No tax-specific sequence was identified which may have contributed to the apparently high degree of transmission from mother to children (three of five children tested) nor account for the differences between disease symptoms in the parents.

3' terminal nucleotide sequence of human astrovirus type 1 and routine detection of astrovirus nucleic acid and antigens

Human astrovirus type 1 was purified by caesium chloride density-gradient centrifugation and the virus was located using an immunodot blot technique with polyclonal rabbit serum, which reacted with all five serotypes. The virus banded with a density of 1.33 g/ml. RNA was extracted from the purified virus, converted into double-stranded cDNA, using an oligo(dT) primer, and cloned into plasmid and M13 vectors. The sequence of the 3' end of astrovirus RNA adjacent to the poly(A) tract was determined. This sequence showed no significant homology with the equivalent region of other positive-sense RNA viruses. Synthetic oligonucleotide primers were designed to amplify specifically astrovirus type 1 RNA in a polymerase chain reaction.