- Email: [email protected]
Evaluation of simian adenoviral vector AdCh63 expressing MSP-1 as a candidate blood-stage malaria vaccine
S427 IgM and IgG). Plasma samples were obtained from patients during the acute phase of their illness. Data on demographic characteristics, pre-morbid conditions, clinical features, and routine haematological and biochemical laboratory test findings were collected and analysed
Laboratory results showed lymphopenia with mean nadir of 0.76 109/L, occurring on mean day 4 of illness and mild thrombocytopenia with mean nadir of 153 109/L.
RESULTS
Since January 2008, locally transmitted CHIKF has been reported in Singapore. From this small pilot study, patients with acute CHIKF presenting to National University Hospital, Singapore from July to August 2008 could be divided into two distinct populations, one of younger migrant workers living in dormitories and one of older Singaporean citizens with higher economic income living in nearby homes with gardens. Common presenting symptoms were fever, myalgia, arthralgia, rash, gastrointestinal symptoms and headache. Further study of CHIKF in Singapore would be valuable to characterize the demographics, symptoms and laboratory results of affected patients
Migrant workers were younger, median age 31 years (range 19 to 37 years), had no comorbidities and worked in heavy industry. In comparison, the four Singaporean citizens were older with median age 56 years (range 52 to 64 years). Two had comorbidities (hypertension and ischemic heart disease). All cases had complained of fever with median duration of 3 days. Other common symptoms included myalgia (89%), arthralgia and rash (78%), gastrointestinal symptoms (67%) and headache (44%).
CONCLUSIONS
0005 MODELING HOW NOSOCOMIAL INFECTIONS SPREAD: DEPENDENCE AND INDEPENDENCE ASSUMPTIONS Joc Cing TAY1, Hardiyanto WIBISONO1 and Paul Ananth TAMBYAH2 1
ROSS Scientific Pte Ltd, Singapore, Singapore, 2National University Hospital, Singapore, Singapore
In most compartmental models of disease spread, spatial-temporal interactions among individuals are homogenous and instantaneous. These assumptions have been gradually replaced by networkbased, time and space-explicit constructs of the environment in individual-based models that are more accurate and mechanistic. The time-series data needed are however, prohibitively large and expensive to collect. In this feasibility study, the authors present a similar attempt based on more easily collected, relative visitation frequencies in staff movement patterns (collected over 2 weeks at a Surgical ICU (SICU) of an academic hospital). We hypothesize that under assumptions of continuity and periodicity of shifts, the timedependent movement patterns are well estimated by relative frequencies. Movement patterns of the SICU staff were collected using the TrackME system from ROSS Scientific. Each individual wears a receiver that logs the places visited and durations of each visit. If he/she visits a location (say A) n times out of a total of m visits to all tracked locations, then the likelihood of he/she visiting A will be n/m among other choices. We do this for modeling miscellaneous activities only.
METHOD Figure 1 represents the average movement patterns of 5 Staff Nurses for 9 tracked locations out of 20 possible locations within the ward.
The edges represent transitions from one location to another, labelled with probabilities. The transition matrix is given in Figure 2 where the transition from location j to location i at time t, is given by Xij where i, j are the row and column indices. A comparison of relative frequencies versus the Markovian steady state vector of this matrix is given in Table 1
RESULTS the error is surprisingly small (RMS error ¼ 0.02) despite the fact that data collected contained discontinuities as they were taken from multiple samples
CONCLUSIONS The preliminary results suggest that under assumptions of a continuous and periodic work pattern, characteristic of staff in the SICU ward, such relative frequencies well approximates the Markovian steady state that was under the more stringent assumption of non-independent activity patterns. If so, they have significant implications on how data can be collected economically and yet providing accurate models of disease carriage.
0006 EVALUATION OF SIMIAN ADENOVIRAL VECTOR ADCH63 EXPRESSING MSP-1 AS A CANDIDATE BLOOD-STAGE MALARIA VACCINE Anna GOODMAN1, Sarah GILBERT1, Stefano COLLOCA2, Matthew DICKS1, Adrian HILL1 and Simon DRAPER1 1
University of Oxford, oxford, United Kingdom, 2Okairos AG, Rome, Italy
Complete protection against Plasmodium yoelii malaria has been demonstrated using a heterologous prime-boost regime with viral vectors encoding the 42 kDa region of merozoite surface protein-1
(MSP-1) in a mouse model. This successful regime incorporated a human adenovirus serotype 5 (AdHu5) prime, boosted eight weeks later with a modified vaccinia virus Ankara (MVA) vector. Adenoviral
S428 vectors have generated great scientific interest in recent years and appear to be superior viral vectors with great potential in vaccine regimes. Their potential use in humans, however, is limited by natural anti-vector immunity to human adenoviruses, but this problem could be largely circumvented by the use of simian adenoviral vaccine vectors. Recent clinical trials have suggested that the simian adenoviral vector AdCh63 is a promising clinical candidate. We have developed vectors (of human and simian origin) and MVA encoding a novel construct based on P. falciparum MSP-1 and have undertaken comparative immunogenicity studies in mice. The antigen, termed ‘PfM128, is based on the five highly conserved blocks from P. falciparum MSP-1, plus both dimorphic alleles of the 42 kDa region. We have used these vectors to map novel murine T cell epitopes within PfMSP-1. We compare antibody titres and polyfunctional T cell responses when simian adenoviral vector AdCh63 is used to replace AdHu5 in a heterologous prime-boost regime. These data suggest that simian adenoviral vectors have great potential for use in future blood-stage malaria vaccination regimes in humans.
METHOD The antigen, termed ‘PfM128’, was inserted into adenoviral vectors AdHu5, AdCh63 (Okairos) and Modified Vaccinia Ankara virus (MVA). BALB/c mice (n ¼ 6/ group) were immunised as follows: AdHu5 PfM128 or AdCh63 PfM128 (1010 vp id) was administered at week 0. MVA PfM128 (107pfu id) was administered at week 8. Sera was taken at weeks 2 and 8 post-prime and week 2 post-boost. Total IgG were measured using ELISA to ETSR and QKNG GST-MSP119. The quantity and quality of the T cell response
to PfM128 was determined using ICS. Spleens were taken at 2 weeks following the final immunisation.
RESULTS Total IgG responses to both allelic forms of MSP-119 were determined by ELISA. No significant differences were found between mice immunised with AdHu5 or AdCh63 PfM118. A CD8 + T cell epitope was identified using overlapping peptide pools. ICS was then used to determine CD8 + IFNg, IL-2 and TNFa responses to peptide stimulation. Both immunisation regimes were found to induce strong CD8 + T cell responses. These responses were polyfunctional, with the majority of CD8 + T cells secreting both IFNg and TNFa and a small proportion of cells secreting IL-2. These cytokine responses did not differ between groups.
CONCLUSIONS Viral vectored vaccines are shown to induce strong cellular and humoural immune responses against an antigen construct based on the blood-stage malaria candidate antigen, P. falciparum MSP-1. We demonstrate that human adenovirus 5 vector can be effectively substituted for a simian adenoviral vector without a reduction in immunogenicity. This work provides evidence a vaccine regime based on simian adenoviral vectors and the blood-stage antigen MSP-1 is likely to be of use in clinical practice. Funding has been obtained to take this work into phase I clinical study of a simian adenoviral vector AdCh63 PfM128, boosted with MVA PfM128.
0008 HLA FOOTPRINTING REVEALS A NOVEL PROTECTIVE CD8 + T CELL RESPONSE IN HEPATITIS C VIRUS INFECTION Karen FITZMAURICE1,2, Danijela PETROVIC1, Silvana GAUDIERI3, Elizabeth FREITAS3, Stuart SIMS2, Aideen LONG1, Dermot KELLEHER1 and Paul KLENERMAN2 1
Trinity College, Dublin, Ireland, 2University of Oxford, Oxford, United Kingdom, 3Murdoch University, Perth, Australia
The cellular immune response is thought to play a key role in determining a successful outcome to HCV infection. CD8+ T cells are central to this process although the key features of a successful CD8+ T cell response remain to be defined. A cohort of Irish women infected by a single source and defined by common age, gender and ethnicity provides an ideal setting in which to examine the impact of specific HLA Class I restricted CD8+ T cells on virologic outcome. In this cohort a strong association between viral clearance and the HLA Class I allele A*03 is described. We proposed that the mechanism underpinning the protective nature of HLA A*03 was the presentation of key immunodominant epitope(s) to CD8 + T cells. In this study, we used a novel approach combining the use of bio-informatic epitope prediction with a unique set of host and viral genetic data to identify a key protective HLA A*03 restricted epitope.
METHOD Selective immune pressures imposed by CD8 + T cell responses are well known to drive escape mutations within targeted T cell epitopes. The reproducible hallmark of this, a ‘‘footprint’’ is visible at population level and reflects viral adaptation to HLA Class I directed responses. We first identified 26 putative A*03 restricted epitopes using different
epitope prediction programs. Viral sequences were then obtained from 9 HLA A*03+ve patients and 19 HLA A*03-ve controls. Polymorphisms within the predicted epitopes were observed and associations linking them to the presence of HLA A*03 were identified. Cellular assays were used to confirm these findings.
RESULTS We observed a strong ‘‘footprint’’ in a novel predicted NS3 epitope (TVYHGAGTK) in HLA A*03 positive patients. In this epitope, lysine was substituted with arginine K1088R, a key anchor position, in 77% of HLA A*03 positive patients vs 5% (p ¼ 0.0002). A second significant substitution of threonine to alanine T1087A was also noted (p ¼ 0.02) and the double substitution TK1087/8AR was found to occur in 55% vs 5% controls (p ¼ 0.007). Peptide-specific CD8 + T cell responses were observed in 60% of patients despite the 3 decades since exposure and T cell recognition was significantly reduced in cells stimulated with the escape mutants.
CONCLUSIONS We propose that the protective effect of HLA A*03 can be attributed to the targeting of this key immunodominant epitope in a conserved
Laboratory results showed lymphopenia with mean nadir of 0.76 109/L, occurring on mean day 4 of illness and mild thrombocytopenia with mean nadir of 153 109/L.
RESULTS
Since January 2008, locally transmitted CHIKF has been reported in Singapore. From this small pilot study, patients with acute CHIKF presenting to National University Hospital, Singapore from July to August 2008 could be divided into two distinct populations, one of younger migrant workers living in dormitories and one of older Singaporean citizens with higher economic income living in nearby homes with gardens. Common presenting symptoms were fever, myalgia, arthralgia, rash, gastrointestinal symptoms and headache. Further study of CHIKF in Singapore would be valuable to characterize the demographics, symptoms and laboratory results of affected patients
Migrant workers were younger, median age 31 years (range 19 to 37 years), had no comorbidities and worked in heavy industry. In comparison, the four Singaporean citizens were older with median age 56 years (range 52 to 64 years). Two had comorbidities (hypertension and ischemic heart disease). All cases had complained of fever with median duration of 3 days. Other common symptoms included myalgia (89%), arthralgia and rash (78%), gastrointestinal symptoms (67%) and headache (44%).
CONCLUSIONS
0005 MODELING HOW NOSOCOMIAL INFECTIONS SPREAD: DEPENDENCE AND INDEPENDENCE ASSUMPTIONS Joc Cing TAY1, Hardiyanto WIBISONO1 and Paul Ananth TAMBYAH2 1
ROSS Scientific Pte Ltd, Singapore, Singapore, 2National University Hospital, Singapore, Singapore
In most compartmental models of disease spread, spatial-temporal interactions among individuals are homogenous and instantaneous. These assumptions have been gradually replaced by networkbased, time and space-explicit constructs of the environment in individual-based models that are more accurate and mechanistic. The time-series data needed are however, prohibitively large and expensive to collect. In this feasibility study, the authors present a similar attempt based on more easily collected, relative visitation frequencies in staff movement patterns (collected over 2 weeks at a Surgical ICU (SICU) of an academic hospital). We hypothesize that under assumptions of continuity and periodicity of shifts, the timedependent movement patterns are well estimated by relative frequencies. Movement patterns of the SICU staff were collected using the TrackME system from ROSS Scientific. Each individual wears a receiver that logs the places visited and durations of each visit. If he/she visits a location (say A) n times out of a total of m visits to all tracked locations, then the likelihood of he/she visiting A will be n/m among other choices. We do this for modeling miscellaneous activities only.
METHOD Figure 1 represents the average movement patterns of 5 Staff Nurses for 9 tracked locations out of 20 possible locations within the ward.
The edges represent transitions from one location to another, labelled with probabilities. The transition matrix is given in Figure 2 where the transition from location j to location i at time t, is given by Xij where i, j are the row and column indices. A comparison of relative frequencies versus the Markovian steady state vector of this matrix is given in Table 1
RESULTS the error is surprisingly small (RMS error ¼ 0.02) despite the fact that data collected contained discontinuities as they were taken from multiple samples
CONCLUSIONS The preliminary results suggest that under assumptions of a continuous and periodic work pattern, characteristic of staff in the SICU ward, such relative frequencies well approximates the Markovian steady state that was under the more stringent assumption of non-independent activity patterns. If so, they have significant implications on how data can be collected economically and yet providing accurate models of disease carriage.
0006 EVALUATION OF SIMIAN ADENOVIRAL VECTOR ADCH63 EXPRESSING MSP-1 AS A CANDIDATE BLOOD-STAGE MALARIA VACCINE Anna GOODMAN1, Sarah GILBERT1, Stefano COLLOCA2, Matthew DICKS1, Adrian HILL1 and Simon DRAPER1 1
University of Oxford, oxford, United Kingdom, 2Okairos AG, Rome, Italy
Complete protection against Plasmodium yoelii malaria has been demonstrated using a heterologous prime-boost regime with viral vectors encoding the 42 kDa region of merozoite surface protein-1
(MSP-1) in a mouse model. This successful regime incorporated a human adenovirus serotype 5 (AdHu5) prime, boosted eight weeks later with a modified vaccinia virus Ankara (MVA) vector. Adenoviral
S428 vectors have generated great scientific interest in recent years and appear to be superior viral vectors with great potential in vaccine regimes. Their potential use in humans, however, is limited by natural anti-vector immunity to human adenoviruses, but this problem could be largely circumvented by the use of simian adenoviral vaccine vectors. Recent clinical trials have suggested that the simian adenoviral vector AdCh63 is a promising clinical candidate. We have developed vectors (of human and simian origin) and MVA encoding a novel construct based on P. falciparum MSP-1 and have undertaken comparative immunogenicity studies in mice. The antigen, termed ‘PfM128, is based on the five highly conserved blocks from P. falciparum MSP-1, plus both dimorphic alleles of the 42 kDa region. We have used these vectors to map novel murine T cell epitopes within PfMSP-1. We compare antibody titres and polyfunctional T cell responses when simian adenoviral vector AdCh63 is used to replace AdHu5 in a heterologous prime-boost regime. These data suggest that simian adenoviral vectors have great potential for use in future blood-stage malaria vaccination regimes in humans.
METHOD The antigen, termed ‘PfM128’, was inserted into adenoviral vectors AdHu5, AdCh63 (Okairos) and Modified Vaccinia Ankara virus (MVA). BALB/c mice (n ¼ 6/ group) were immunised as follows: AdHu5 PfM128 or AdCh63 PfM128 (1010 vp id) was administered at week 0. MVA PfM128 (107pfu id) was administered at week 8. Sera was taken at weeks 2 and 8 post-prime and week 2 post-boost. Total IgG were measured using ELISA to ETSR and QKNG GST-MSP119. The quantity and quality of the T cell response
to PfM128 was determined using ICS. Spleens were taken at 2 weeks following the final immunisation.
RESULTS Total IgG responses to both allelic forms of MSP-119 were determined by ELISA. No significant differences were found between mice immunised with AdHu5 or AdCh63 PfM118. A CD8 + T cell epitope was identified using overlapping peptide pools. ICS was then used to determine CD8 + IFNg, IL-2 and TNFa responses to peptide stimulation. Both immunisation regimes were found to induce strong CD8 + T cell responses. These responses were polyfunctional, with the majority of CD8 + T cells secreting both IFNg and TNFa and a small proportion of cells secreting IL-2. These cytokine responses did not differ between groups.
CONCLUSIONS Viral vectored vaccines are shown to induce strong cellular and humoural immune responses against an antigen construct based on the blood-stage malaria candidate antigen, P. falciparum MSP-1. We demonstrate that human adenovirus 5 vector can be effectively substituted for a simian adenoviral vector without a reduction in immunogenicity. This work provides evidence a vaccine regime based on simian adenoviral vectors and the blood-stage antigen MSP-1 is likely to be of use in clinical practice. Funding has been obtained to take this work into phase I clinical study of a simian adenoviral vector AdCh63 PfM128, boosted with MVA PfM128.
0008 HLA FOOTPRINTING REVEALS A NOVEL PROTECTIVE CD8 + T CELL RESPONSE IN HEPATITIS C VIRUS INFECTION Karen FITZMAURICE1,2, Danijela PETROVIC1, Silvana GAUDIERI3, Elizabeth FREITAS3, Stuart SIMS2, Aideen LONG1, Dermot KELLEHER1 and Paul KLENERMAN2 1
Trinity College, Dublin, Ireland, 2University of Oxford, Oxford, United Kingdom, 3Murdoch University, Perth, Australia
The cellular immune response is thought to play a key role in determining a successful outcome to HCV infection. CD8+ T cells are central to this process although the key features of a successful CD8+ T cell response remain to be defined. A cohort of Irish women infected by a single source and defined by common age, gender and ethnicity provides an ideal setting in which to examine the impact of specific HLA Class I restricted CD8+ T cells on virologic outcome. In this cohort a strong association between viral clearance and the HLA Class I allele A*03 is described. We proposed that the mechanism underpinning the protective nature of HLA A*03 was the presentation of key immunodominant epitope(s) to CD8 + T cells. In this study, we used a novel approach combining the use of bio-informatic epitope prediction with a unique set of host and viral genetic data to identify a key protective HLA A*03 restricted epitope.
METHOD Selective immune pressures imposed by CD8 + T cell responses are well known to drive escape mutations within targeted T cell epitopes. The reproducible hallmark of this, a ‘‘footprint’’ is visible at population level and reflects viral adaptation to HLA Class I directed responses. We first identified 26 putative A*03 restricted epitopes using different
epitope prediction programs. Viral sequences were then obtained from 9 HLA A*03+ve patients and 19 HLA A*03-ve controls. Polymorphisms within the predicted epitopes were observed and associations linking them to the presence of HLA A*03 were identified. Cellular assays were used to confirm these findings.
RESULTS We observed a strong ‘‘footprint’’ in a novel predicted NS3 epitope (TVYHGAGTK) in HLA A*03 positive patients. In this epitope, lysine was substituted with arginine K1088R, a key anchor position, in 77% of HLA A*03 positive patients vs 5% (p ¼ 0.0002). A second significant substitution of threonine to alanine T1087A was also noted (p ¼ 0.02) and the double substitution TK1087/8AR was found to occur in 55% vs 5% controls (p ¼ 0.007). Peptide-specific CD8 + T cell responses were observed in 60% of patients despite the 3 decades since exposure and T cell recognition was significantly reduced in cells stimulated with the escape mutants.
CONCLUSIONS We propose that the protective effect of HLA A*03 can be attributed to the targeting of this key immunodominant epitope in a conserved