Recombinant human papillomavirus (HPV) type 16 L1 virus-like particles (VLPs) expressed in the ba... more Recombinant human papillomavirus (HPV) type 16 L1 virus-like particles (VLPs) expressed in the baculovirus system were used to investigate the cellular immune response to human papillomavirus type 16. The cell-mediated immune response was evaluated through immunization of mice with HPV 16 L1 virus-like particles using a lymphoproliferation assay and cytokine production and cytometric analysis of lymphocyte subsets. A significant proliferative response was observed which was associated with secretion of both interferon-gamma and interleukin-2. FACS analysis of splenic lymphocytes revealed that CD8+ T-cells were increased in the immunized mice. These results demonstrate that HPV 16 L1 VLPs induce a T-cell response characterized by a Th1 profile and confirm that the HPV 16 VLP is a reasonable candidate for vaccine development.
Environmental surveillance is important in high-risk areas of hospitals to prevent fungal infecti... more Environmental surveillance is important in high-risk areas of hospitals to prevent fungal infections in immunosuppressed patients. Conventional culture methods for enumerating environmental fungi are time-consuming. In this field study, a solid-phase cytometry technique (SPC) and a more conventional culture-based method to quantify fungal contamination of hospital air and surface samples were compared. For the air sampling, a liquid cyclone air sampler was used with a flow rate of 300 L/min for 10 min in each of four hospital locations. Surface swabbing was done in two locations, with two different swab types. Samples from all areas were processed by SPC and by culture on malt extract agar. The mean airborne concentrations of viable fungi determined by SPC were about 1.5-fold higher than the mean concentrations obtained with the culture-based method. These differences for air samples were significant in three hospital environments. No significant difference was observed for surface samples between the two swab types and between the two analytical methods. One of the prominent advantages of SPC was its rapidity in comparison with the culture-based method (5 h versus 5 days). In this study, we showed that SPC allows for rapid monitoring of viable fungi in hospital environments. SPC can thus be used to provide an early warning and a rapid implementation of corrective measures. Viable fungi detection may be an important tool to assess infectious risk in wards with immunosuppressed patients.
Two types of porcine circovirus (PCV) have been isolated and are referred to as PCV1 and PCV2. PC... more Two types of porcine circovirus (PCV) have been isolated and are referred to as PCV1 and PCV2. PCV1 represents an apathogenic virus, whereas PCV2 is associated with post-weaning multisystemic wasting syndrome. The two PCVs are related, since they display about 70% identity based on nucleotide sequences. In order to discriminate between common and type-specific antigens, an immunocytological approach was used following transfections with cloned circovirus DNAs, as well as recombinant proteins expressed by either baculovirus or plasmid vectors. The ORF1-encoded proteins in the two viruses were shown to be antigenically related, whereas the ORF2 proteins were recognized differentially by polyclonal anti-PCV2 antibodies. Furthermore, PEPSCAN analysis performed on overlapping fragments of the genes encoding part of ORF1 and the entire ORF2 and ORF3 led to the identification of five dominant immunoreactive areas, one located on ORF1 and four on ORF2. However, only some ORF2 peptides prove...
The L1 major capsid protein of human papillomavirus type 16 (HPV-16) was expressed in Sf-21 insec... more The L1 major capsid protein of human papillomavirus type 16 (HPV-16) was expressed in Sf-21 insect cells with a recombinant baculovirus. Virus-like particles obtained were purified and used to develop an enzyme-linked immunosorbent assay for detection of anti-HPV-16 antibodies in sera from 76 women with evidence of genital HPV infection and 79 controls. HPV-16-infected individuals developed antibodies directed at HPV-16 virions since reactivity against recombinant HPV-16L1 capsids was observed in 50% of them compared with only 6% in the general adult population. However, some cross-reactivities with sera from women infected with others HPV types were observed.
An hepatitis B immunization programme was initiated in Senegal in 1978, and infants included in t... more An hepatitis B immunization programme was initiated in Senegal in 1978, and infants included in this controlled study have been followed for a period of 2-12 years after immunization. During this period HBV infections have been observed both in vaccinated and non-vaccinated infants. The polymerase chain reaction was used to search for HBV DNA sequences in the sera of 153 children with evidence of serum markers of past or present HBV replication. Amplified HBV DNA sequences were detected in 93% of the HBsAg positive individuals, in 58% of those only positive for antiHBc antibodies and in 7.8% of antiHBs and antiHBc positive infants. The results confirm the high efficiency and long-lasting effectiveness of HB vaccine.
Eight monoclonal antibodies directed against the surface protein of hepatitis B virus (HBV) were ... more Eight monoclonal antibodies directed against the surface protein of hepatitis B virus (HBV) were tested using an epitope-mapping system (Pepscan) for characterizing antigenic domains. Four different amino acid sequences corresponding to linear epitopes were identified: one in pre-S1 corresponding to the sequence 29-36, two in pre-S2 corresponding to overlapping sequences 134-141 and 137-144, and one in the S region of the protein corresponding to the amino acid sequence 117-126.
Recombinant human papillomavirus (HPV) type 16 L1 virus-like particles (VLPs) expressed in the ba... more Recombinant human papillomavirus (HPV) type 16 L1 virus-like particles (VLPs) expressed in the baculovirus system were used to investigate the cellular immune response to human papillomavirus type 16. The cell-mediated immune response was evaluated through immunization of mice with HPV 16 L1 virus-like particles using a lymphoproliferation assay and cytokine production and cytometric analysis of lymphocyte subsets. A significant proliferative response was observed which was associated with secretion of both interferon-gamma and interleukin-2. FACS analysis of splenic lymphocytes revealed that CD8+ T-cells were increased in the immunized mice. These results demonstrate that HPV 16 L1 VLPs induce a T-cell response characterized by a Th1 profile and confirm that the HPV 16 VLP is a reasonable candidate for vaccine development.
Environmental surveillance is important in high-risk areas of hospitals to prevent fungal infecti... more Environmental surveillance is important in high-risk areas of hospitals to prevent fungal infections in immunosuppressed patients. Conventional culture methods for enumerating environmental fungi are time-consuming. In this field study, a solid-phase cytometry technique (SPC) and a more conventional culture-based method to quantify fungal contamination of hospital air and surface samples were compared. For the air sampling, a liquid cyclone air sampler was used with a flow rate of 300 L/min for 10 min in each of four hospital locations. Surface swabbing was done in two locations, with two different swab types. Samples from all areas were processed by SPC and by culture on malt extract agar. The mean airborne concentrations of viable fungi determined by SPC were about 1.5-fold higher than the mean concentrations obtained with the culture-based method. These differences for air samples were significant in three hospital environments. No significant difference was observed for surface samples between the two swab types and between the two analytical methods. One of the prominent advantages of SPC was its rapidity in comparison with the culture-based method (5 h versus 5 days). In this study, we showed that SPC allows for rapid monitoring of viable fungi in hospital environments. SPC can thus be used to provide an early warning and a rapid implementation of corrective measures. Viable fungi detection may be an important tool to assess infectious risk in wards with immunosuppressed patients.
Two types of porcine circovirus (PCV) have been isolated and are referred to as PCV1 and PCV2. PC... more Two types of porcine circovirus (PCV) have been isolated and are referred to as PCV1 and PCV2. PCV1 represents an apathogenic virus, whereas PCV2 is associated with post-weaning multisystemic wasting syndrome. The two PCVs are related, since they display about 70% identity based on nucleotide sequences. In order to discriminate between common and type-specific antigens, an immunocytological approach was used following transfections with cloned circovirus DNAs, as well as recombinant proteins expressed by either baculovirus or plasmid vectors. The ORF1-encoded proteins in the two viruses were shown to be antigenically related, whereas the ORF2 proteins were recognized differentially by polyclonal anti-PCV2 antibodies. Furthermore, PEPSCAN analysis performed on overlapping fragments of the genes encoding part of ORF1 and the entire ORF2 and ORF3 led to the identification of five dominant immunoreactive areas, one located on ORF1 and four on ORF2. However, only some ORF2 peptides prove...
The L1 major capsid protein of human papillomavirus type 16 (HPV-16) was expressed in Sf-21 insec... more The L1 major capsid protein of human papillomavirus type 16 (HPV-16) was expressed in Sf-21 insect cells with a recombinant baculovirus. Virus-like particles obtained were purified and used to develop an enzyme-linked immunosorbent assay for detection of anti-HPV-16 antibodies in sera from 76 women with evidence of genital HPV infection and 79 controls. HPV-16-infected individuals developed antibodies directed at HPV-16 virions since reactivity against recombinant HPV-16L1 capsids was observed in 50% of them compared with only 6% in the general adult population. However, some cross-reactivities with sera from women infected with others HPV types were observed.
An hepatitis B immunization programme was initiated in Senegal in 1978, and infants included in t... more An hepatitis B immunization programme was initiated in Senegal in 1978, and infants included in this controlled study have been followed for a period of 2-12 years after immunization. During this period HBV infections have been observed both in vaccinated and non-vaccinated infants. The polymerase chain reaction was used to search for HBV DNA sequences in the sera of 153 children with evidence of serum markers of past or present HBV replication. Amplified HBV DNA sequences were detected in 93% of the HBsAg positive individuals, in 58% of those only positive for antiHBc antibodies and in 7.8% of antiHBs and antiHBc positive infants. The results confirm the high efficiency and long-lasting effectiveness of HB vaccine.
Eight monoclonal antibodies directed against the surface protein of hepatitis B virus (HBV) were ... more Eight monoclonal antibodies directed against the surface protein of hepatitis B virus (HBV) were tested using an epitope-mapping system (Pepscan) for characterizing antigenic domains. Four different amino acid sequences corresponding to linear epitopes were identified: one in pre-S1 corresponding to the sequence 29-36, two in pre-S2 corresponding to overlapping sequences 134-141 and 137-144, and one in the S region of the protein corresponding to the amino acid sequence 117-126.
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Papers by P. Le Cann