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Background: The relationship among cytomegalovirus (CMV) infection and the serum level of chemokines and soluble adhesion molecules is not well studied. This study aimed to assess chemokines and soluble adhesion molecules in CMV-positive Saudi renal transplant recipients. Methodology: The study was conducted in a tertiary hospital in Eastern Saudi Arabia over a 12-month period. All kidney transplant recipients who regularly attended the nephrology clinics were included (n = 150). Randomly selected age- and sex-matched individuals served as a control group (n = 158). CMV antibodies (IgG and IgM), chemokines and soluble adhesion molecules were measured using standard enzyme-linked immunosorbent assay (ELISA). CMV viral DNA was detected using real time polymerase chain reaction (PCR). Results: Of the 150 patients studied, 149 (n = 150) had detectable levels of Anti-CMV IgG antibodies (99.3%). In the control group, 113 (n = 158), blood donors had anti-CMV IgG antibodies (71.5%). Forty-one (n = 150) kidney transplant recipients were positive for anti-CMV IgM antibodies (27.3%), whereas only one (n = 158) blood donor had detectable anti-CMV IgM antibodies. All IgM positive samples contained CMV viral DNA. MCP-1, IL-8, ICAM-1, and VCAM-1 levels were measured using ELISA. Of those, only MCP-1 and IL-8 were detectable. Eighteen kidney transplant recipients were positive for MCP-1 (12%). All MCP-1 patients were also anti-CMV IgM positive, while 5 patients had detectable levels of IL-8 (3.3%). All these patients were CMV IgM-positive. Conclusions: The increase in chemokine levels during CMV infection may reflect a possible role for these molecules in the immunopathogenesis of CMV infection in this study population.

Injecting drug users are at increased risk of infection with hepatitis viruses and blood-borne pathogens. The aim of this study was to examine HBV, HCV, HDV, and TTV infections in Saudi drug users (N = 344). Extraction of nucleic acid from serum, reverse-transcription, amplification of viral nucleic acids, and HBV and HCV genotyping were done using established techniques. Of the analyzed samples, 41 (12%) contained detectable HBV DNA, 131 (38%) contained detectable HCV RNA, and 174 (51%) had detectable TTV DNA. The predominant HBV genotype was found to be genotype D and the predominant HCV genotype was found to be genotype 1b. All the samples were negative for HDV. Twelve samples (3.5%) were found to contain mixed HBV and HCV genomes, 24 samples (7%) were found to contain mixed HBV and TTV genomes, 82 samples (24%) were found to contain mixed HCV and TTV genomes, and 9 samples (2.6%) were found to contain mixed HBV, HCV, and TTV genomes. Identification of various infections in drug users will help the control of these infections in this group as well as in the community. J. Med. Virol. 81:1343–1347, 2009. © 2009 Wiley-Liss, Inc.

We used a lentiviral vector bearing the viral spike protein to detect neutralizing antibodies against Middle East respiratory syndrome coronavirus (MERS-CoV) in persons from the Eastern Province of Saudi Arabia. None of the 268 samples tested displayed neutralizing activity, which suggests that MERS-CoV infections in humans are infrequent in this province.

Balb/c mice were immunized intranasally (i.n.) with a chimeric synthetic peptide containing two copies of a T- and one copy of a B-cell epitope (TTB) from measles virus (MV) fusion protein, plus cholera toxin B (CTB) adjuvant. The antibodies induced cross-reacted with, and neutralized MV and on passive transfer, protected mice against encephalitis induced by neuroadapated MV. Immunization with TTB alone induced antibodies which increased survival but not significantly compared to controls. Furthermore, i.n. immunization with TTB plus CTB induced TTB-specific IgA antibodies in saliva and nasal washes. Co-administration of CTB increased the affinity of antibodies to the B-cell epitope of TTB and caused a relative increase in the level of anti-peptide antibodies of the IgG2a subclass and the overall titre of IgG antibodies. These results indicate the potential of the i.n. route for immunization with synthetic peptide immunogens for induction of both local and systemic anti-peptide antibody responses.

Background Kaposi's sarcoma herpesvirus (KSHV) causes Kaposi's sarcoma (KS), primary effusion lymphoma, and multicentric Castleman's disease in immunocompromised patients including allograft recipients. Detection of KSHV DNA in blood, as well as host genetic polymorphisms has been found to be associated with an increased risk for KS. We investigated an association between single nucleotide polymorphisms (SNPs) in vascular endothelial growth factor A (VEGFA) gene region and KSHV viremia in kidney transplant recipients (KTR) in Saudi Arabia. Methods In total, 152 KTR who have survived kidney transplantation for at least 6 months were included in the study. KSHV viremia was determined by real-time polymerase chain reaction (PCR). Genotyping of SNPs in the VEGFA region was performed by PCR and direct sequencing, as well as by restriction fragment length polymorphism. Results KSHV DNA was detected in 28.9% (n = 44) of the study population. The A-allele at position C172A VEGFA gene promoter region was found to be associated with KSHV viremia (odd ratio [OR] = 4.8, P = 0.005). In addition, the G-allele at position C+405G in the 5′-untranslated region was associated with KSHV viremia in women, but not in men (OR = 3.98, P = 0.004). Conclusions Our results suggest an association of VEGFA polymorphisms with KSHV viremia among KTR in this study population. A limitation of our study is that the results can only be predicated for patients 6 months after kidney transplantation and should be validated in another cohort with larger sample size.

Synthetic peptides representing T- and B-cell epitopes from the fusion (F) protein of measles virus (MV) were tested for their ability to induce a protective immune response against intracerebral challenge with neuroadapted strains of MV and canine distemper virus (CDV) in mice. Of the panel of peptides tested, only a chimeric peptide consisting of two copies of a promiscuous T-cell epitope (representing residues 288 to 302 of MV F protein) synthesized at the amino terminus of a B-cell epitope (representing residues 404 to 414 of MV F protein) was able to induce a protective response against challenge with MV and CDV in inbred mice. The protective response induced by this peptide (TTB) was associated with a significant reduction in mortality, histological absence of acute encephalitis, and greatly reduced titers of virus in the brains of TTB-immune mice following challenge compared with the results for nonimmunized controls. A chimeric peptide comprising one copy of the T-cell epitope and one copy of the B-cell epitope (TB) did not induce a protective response. A comparison of the antibody responses induced by the two chimeras suggested that differences in protective efficacy following immunization may be a result of the higher affinity of the antibody induced by the TTB peptide than that of the antibody induced by the TB peptide. In addition, differences in the immunoglobulin G subclass of the antipeptide antibody responses were observed, and these may play a role in the differences in protection observed. These results indicate that appropriately designed synthetic peptides have potential as vaccines for the induction of cross-reactive protection against morbilliviruses.

Introduction: Few reports about the prevalence and genetic basis of extended spectrum beta-lactamases (ESBLs) are available from Saudi Arabia. We sought to determine the prevalence of ESBL-producing Enterobacteriaceae in a university hospital in eastern Saudi Arabia and to characterize the ESBLs produced by these isolates at the molecular level. Methodology: All clinical isolates of Escherichia coli, Klebsiella spp., and Proteus spp. collected over two years were evaluated for susceptibility to a panel of antimicrobials and were analyzed for the ESBL phenotype using screening and confirmatory tests. ESBL-positive isolates were then screened for the presence of genes encoding CTX-M, SHV, and TEM beta-lactamases by PCR. Results and conclusions: The overall prevalence of ESBL-producing isolates was 4.8% (253/5256). Most isolates (80%) were from the inpatient department. The ESBL phenotype was more frequently detected in K. pneumonia. CTX-M genes were the most prevalent ESBL genes, detected in 82% of the studied isolates. The ESBL producers demonstrated a high multidrug resistance rate (96.6%). In transconjugation assay, the same ESBL gene pattern was transmitted from 29.7% of K. pneumoniae donors to the recipient strain, and the latter exhibited concomitant decreased aminoglycosides and co-trimoxazole susceptibility. We observed the presence of ESBL screen-positive but confirmatory-negative isolates (8.9%). Phenotypic tests for the production of AmpC β-lactamase tested positive in 52% of these isolates. Further studies are needed for appropriate detection of concomitant ESBL and AmpC enzyme production among such isolates. Continued surveillance and judicious antibiotic usage together with the implementation of efficient infection control measures are absolutely required.

In this study, a panel of 55 synthetic peptides representing 92.2% of the haemagglutinin (H) glycoprotein of measles virus (MV) were used to study the antigenic profile of the H molecule of anti-MV antibodies raised in mice and late convalescent human sera. In addition the immunogenicity of these peptides was tested in two mouse strains. Mouse anti-MV antibodies had different fine specificity of binding to the peptides depending on the mouse strain. Thus in BALB/c (H-2 d ) mice, anti-MV antibodies recognised six peptides representing residues 103–117; 123–137; 242–255; 293–307 and 463–477. In TO (H-2 s ) mice, anti-MV antibodies recognised peptides representing residues 49–72 and 463–477. When the immunogenicity of the peptides was tested, 29 were immunogenic in BALB/c mice and 34 were immunogenic in TO mice. Several of the anti-peptide antisera were found to cross-react with MV, depending on the solid phase assay system used but none were able to inhibit virus infectivity in vitro. The reactivity of a panel of late convalescent human sera with the peptides was heterogeneous and the extent of the binding to the peptides was related to the titre of anti-MV. However, human sera recognized certain peptides more frequently than others, in particular peptides at the carboxyl-terminus.

Hepatitis C virus (HCV) has a major impact on public health. In spite of the progress made in the prevention of transfusion-transmitted infections over the last years, these still occur, especially in multi-transfused patients such as sickle cell anemia patients. Sickle cell disease (SCD) is highly prevalent in Eastern Saudi Arabia. Little is known about the prevalence of HCV in Saudi sickle cell disease patients. The present study aimed to assess HCV and HBV antigens, antibodies and viral genome among sickle cell anemia patients in a tertiary hospital in Eastern Saudi Arabia. Methods used included measurement of HCV antigen and antibodies using the novel HCV antigen/antibody combination assay, assessment of HCV core antigen and measurement of viral genome using standard commercial kits. Of the 138 sickle cell disease samples tested, 5 (3.6%) samples gave positive results. Their hemoglobin ranged between 7.8 and 10.1 g/dL, their erythrocyte count ranged between 3.1¥106 and 3.9¥106. Out of these 5 samples, 4 were also positive by the HCV Core Ag assay and by the HCV RNA PCR test (80%). None of the control group was positive. Seven patients were positive for HBs antibodies. One sample was positive for HBsAg, and this indicates chronic carrier state. Improving the testing for blood-borne infections such as HCV and HBV will result in better control of these infections in sickle cell disease patients which will inevitably lead to lower mortality and morbidity in this group of patients.

Introduction: Parvovirus B19 is a cause of hemolysis and red blood cell aplasia in patients with sickle cell anemia. The present study aimed to assess parvovirus B19 infection among sickle cell anemia patients. Methodology: All patients (n = 138) included in the study were sickle cell anemia patients. Blood donors were used as a control group. Assessment of parvovirus B19 antibodies and viral DNA was performed using established methods of detection and B19 recomBlot assay. Results: Detectable levels of parvovirus B19 IgG were found in 52 samples (37.6%) whereas anti-parvovirus B19 IgM antibodies were detected in four (2.89 %) patients of the sickle-cell anemia group. Anti-B19 IgM-positive samples contained B19-viral DNA. These four patients presented with fever, malaise, pallor and no cutaneous rash. Anti-parvovirus B19 antibodies were detected in 22 (39.3%) of the control blood donors group. Anti-parvovirus B19 IgM antibodies were not detected in the control group. Using the recomBlot assay, 58 test samples (42%) were found to contain detectable levels of Parvovirus B19 antibodies. All the samples that were positive for parvovirus B19 IgG by the ELISA were also positive by the recomBlot assay. Six samples were only positive by the recomBlot assay and not by the ELISA. Two of these six samples were positive for B19 viral DNA. Conclusions: Establishing the extent of parvovirus B19 infection in sickle cell anemia patients will help in proper management of aplastic crisis in such patients. The B19 recomBlot assay may be suitable as a confirmatory assay.

Background: The simultaneous detection of antigen and antibody was originally described for the early detection of the human immunodeficiency virus (HIV). The same approach was applied to detect the hepatitis C virus (HCV). The aim of this work was to use the antigen and antibody combination assay for the detection of HCV and HIV infections in expatriates in Eastern Saudi Arabia. Methodology: The study group (N = 875) included expatriate workers of both sexes who were undergoing mandatory pre-employment testing. Detection of anti-HCV antibodies, HCV core antigen, HCV viral RNA, HIV antigens and antibodies was conducted using commercially available kits. Results: Of the 875 samples that were screened for HCV-specific antibodies, four (0.46%) tested positive (two from Pakistan, one from India, and one from the Philippines) and two (0.23%) were equivocal (one from Egypt and one from Nepal). All four samples that were positive for HCV-specific antibodies also tested positive using HCV RNA assay and the HCV antigen-antibody combination assay. The two samples that were equivocal tested positive using the HCV RNA assay and the HCV antigen-antibody combination assay. Of the 875 samples that were tested for HIV antibodies, only one (0.11%) sample gave repeatedly positive results. The same sample also tested repeatedly positive using the HIV combination assay. These results were subsequently confirmed by HIV western blot assay. Conclusions: Our study indicates that the addition of antigen detection to the screening of HCV and HIV may lower the risk of transmission of these viruses in the host country and contribute to the overall control of HCV and HIV in Saudi Arabia.

Synthetic peptides mimicking a conformational B-cell epitope (M2) of the measles virus fusion protein (MVF) were used for the immunization of BALB/c mice and the anti-peptide and anti-virus antibody titers induced were compared. Of the panel of tested peptides, a chimeric peptide consisting of two copies of a T-helper epitope (residues 288–302 of MVF) and one copy of the mimotope M2 (TTM2) and a multiple antigen peptide with eight copies of M2 (MAP-M2) induced the highest titers of anti-M2 and anti-MV antibodies. Furthermore, peptides TTM2 and MAP-M2 induced antibodies with highest affinity for the mimotope and highest avidity for measles virus. Immunization with the MAP-M2 construct induced high titers of high-affinity anti-M2 antibody despite the absence of a T-helper epitope, and lymphocyte proliferation data suggest that the addition of M2 to the MAP resulted in the generation of a structure capable of stimulating T-cell help. Sera with anti-M2 reactivity were pooled according to affinity values for binding to M2, and high- and low-affinity pools were tested for their ability to prevent MV-induced encephalitis in a mouse model. The high-affinity serum pool conferred protection in 100% of mice, whereas the lower affinity pool conferred protection to only 50% of animals. These results indicate the potential of mimotopes for use as synthetic peptide immunogens and highlight the importance of designing vaccines to induce antibodies of high affinity.

Cytotoxic T-lymphocyte (CTL) responses to measles virus (MV) play an important role in recovery from infection, with one of the major target proteins for CTL activity being the nucleoprotein (Np). In this report, a replication-deficient adenovirus-5 recombinant, expressing for MV Np (Rad68) was tested for in vivo priming of MV Np-specific CTL responses in BALB/c and CBA mice. In both strains of mice strong Np-specific CTL responses were induced and these responses were shown to be MHC class I restricted. Using overlapping 15mer peptides spanning residues 1-505 of MV Np a single epitope comprising residues 281-295 was identified in BALB/c mice whereas, in CBA mice two epitopes comprising residues 51-65 and 81-95, were identified. These epitopes were found to contain class I motifs for H-2L(d) and H-2K(k) MHC molecules, respectively. Immunization of BALB/c and CBA mice with the respective CTL epitopes resulted in the in vivo induction of peptide-and MV Np-specific CTL responses. In addition, the identified H-2K(k) restricted CTL epitopes conferred some protection against encephalitis induced following intracerebral challenge with a lethal dose of canine distemper virus (the Np of which shares 70% sequence homology with MV Np). These findings highlight the potential of using well-defined CTL epitopes to control virus infection.

Respiratory syncytial virus (RSV)-specific cytotoxic T lymphocytes (CTL) or neutralizing antibodies can protect against RSV infection when induced separately by immunization with synthetic peptides. In the work described here, RSV-specific neutralizing antibodies and CTLs were induced after immunization with a cocktail of peptides consisting of a B-cell mimotope (S1S-MAP), a T-helper epitope (SH:45-60) and a CTL epitope linked to a fusion (F) peptide (F/M2:81-95) that were comparable to those induced by the peptides alone. Following challenge, a 190-fold reduction in RSV titre was observed in the lungs of peptide cocktail-immunized mice. The combination of RSV-specific humoral and cellular immunity induced by the peptide cocktail was thus more effective at clearing RSV than peptide-induced humoral or cellular immunity alone.

Plasmid DNA vectors have been constructed with minigenes encoding a single cytotoxic T lymphocyte (CTL) epitope from either the M2 protein of respiratory syncytial virus (RSV) or from the nucleoprotein of measles virus (MV) with or without a signal sequence (also called secretory or leader sequence). Following intradermal immunization, plasmids in which the CTL epitopes were expressed in-frame with the signal sequence were more effective at inducing peptide- and virus-specific CTL responses than plasmids expressing CTL epitopes without the signal sequence. This immunization resulted in protection against MV-induced encephalitis and a significant reduction in viral load following RSV challenge. The reduction of viral load following RSV challenge was abrogated by prior injection with anti-IFN-gamma antibodies. These results highlight the ability of epitope-based DNA immunization to induce protective immune responses to well-defined epitopes and indicate the potential of this approach for the development of vaccines against infectious diseases.

Respiratory syncytial virus (RSV) is the most important cause of bronchiolitis and pneumonia in infants and young children worldwide. As yet, there is no effective vaccine against RSV infection, and previous attempts to develop a formalin-inactivated vaccine resulted in exacerbated disease in recipients subsequently exposed to the virus. In the work described here, a combinatorial solid-phase peptide library was screened with a protective monoclonal antibody (MAb 19) to identify peptide mimics (mimotopes) of a conserved and conformationally-determined epitope of RSV fusion (F) protein. Two sequences identified (S1 [HWYISKPQ] and S2 [HWYDAEVL]) reacted specifically with MAb 19 when they were presented as solid-phase peptides. Furthermore, after amino acid substitution analyses, three sequences derived from S1 (S1S [HWSISKPQ], S1K [KWYISKPQ], and S1P [HPYISKPQ]), presented as multiple antigen peptides (MAPs), also showed strong reactivity with MAb 19. The affinity constants of the binding of MAb 19, determined by surface plasmon resonance analyses, were 1.19 × 10 9 and 4.93 × 10 9 M −1 for S1 and S1S, respectively. Immunization of BALB/c mice with these mimotopes, presented as MAPs, resulted in the induction of anti-peptide antibodies that inhibited the binding of MAb 19 to RSV and neutralized viral infection in vitro, with titers equivalent to those in sera from RSV-infected animals. Following RSV challenge of S1S mimotope-immunized mice, a 98.7% reduction in the titer of virus in the lungs was observed. Furthermore, there was a greatly reduced cell infiltration in the lungs of immunized mice compared to that in controls. These results indicate the potential of peptide mimotopes to protect against RSV infection without exacerbating pulmonary pathology.

International audience; A synthetic peptide representing residues 397-420 from the measles virus (MV) fusion (F) protein was tested for its structure, immunogenicity and protective capacity against intracerebral challenge with a neuroadapted strain of MV. Analysis of the peptide by mass spectrometry showed that it was linear, despite the presence of two cysteine residues in the sequence. Circular dichroism spectroscopy highlighted a weak preference for the peptide to adopt an alpha-helical conformation. The peptide was shown to be immunogenic in BALB/c and C57BL/6 mice after intraperitoneal immunization in Freund's adjuvant, and anti-peptide antibodies from both strains of mice reacted with the MV as a solid phase antigen on an ELISA plate. When the fine specificity of the anti-peptide antibody response was examined using overlapping 8-mer peptides, serum antibodies from BALB/c mice recognized the region between residues 407-417 whereas antibodies from C57BL/6 mice recognized the region 408-420 of the 397-420 peptide sequence. Although anti-397-420 antibodies had no demonstrable neutralizing activity, protection against challenge with a neuroadapted strain of MV was demonstrated following active immunization with peptide in C57BL/6 mice or after passive transfer of anti-peptide antibodies in BALB/c mice. These findings highlight the importance of the 397-420 region in the induction of protective antibodies in the MV encephalitis mouse model, and suggest that this epitope might be a good candidate for inclusion in a future MV synthetic peptide vaccine.

Polyclonal sera obtained from African children with acute measles were used to screen a panel of 15-mer overlapping peptides representing the sequence of measles virus (MV) fusion (F) protein. An immunodominant antigenic region from the F protein (p32; amino acids 388 to 402) was found to represent an amino acid sequence within the highly conserved cysteine-rich domain of the F protein of paramyxoviruses. Epitope mapping of this peptide indicated that the complete 15-amino-acid sequence was necessary for high-affinity interaction with anti-MV antibodies. Immunization of two strains of mice with the p32 peptide indicated that it was immunogenic and could induce antipeptide antibodies which cross-reacted with and neutralized MV infectivity in vitro. Moreover, passive transfer of antipeptide antibodies conferred significant protection against fatal rodent-adapted MV-induced encephalitis in susceptible mice. These results indicate that this epitope represents a candidate for inclusion in a future peptide vaccine for measles.

Aims: To identify peptides that mimic (mimotopes) conformational and protective epitopes of RSV fusion protein and to assess their efficacy as immunogens and potential vaccines. Material and methods: An 8-mer solid- phase (TG resin) library was screened with a neutralising and protective RSV fusion protein specific monoclonal antibodies (Mab-19). After selection of positive beads, reactive sequences were identified by microsequencing and 8- mer peptides were synthesised. Improvement of binding was analysed by amino acid replacement using the SPOTs method. Results: Mabs were not able to bind to the free and soluble peptides, nor did these peptides induce anti-RSV specific antibodies. However, several peptides re-synthesised on a TG resin (to produce de-protected 8-mer peptides linked to the resin) or as SPOTs reacted specifically. Therefore it was critical to be able to reproduce this conformation in order to use these mimotopes as immunogens and potential vaccines. Using C-terminal constrained versions of the mimotopes, strong binding of one of the Mabs to the peptides was demonstrated by surface- plasmon resonance. Immunisation of Balb/c mice with these peptide-mimics produced anti-sera that: (1) reacted specifically with RSV; (2) inhibited the binding of the Mab to the virus; (3) neutralised RSV in vitro with high titres (range: 80-640); and (4) reduce significantly the vital load in the lungs of mice challenged with RSV (P < 0.01). Conclusions: This report demonstrates for the first time that: (1) a protective epitope of the conserved RSV fusion protein can be mimicked by synthetic peptides: and (2) immunisations with these mimotopes induced specific anti-RSV neutralising antibodies and reduced vital load in vivo. These results represent a novel concept for the development of a vaccine against RSV.

A solid-phase 8-mer random combinatorial peptide library was used to generate a panel of mimotopes of an epitope recognized by a monoclonal antibody to the F protein of measles virus (MV). An inhibition immunoassay was used to show that these peptides were bound by the monoclonal antibody with different affinities. BALB/c mice were coimmunized with the individual mimotopes and a T-helper epitope peptide (from MV fusion protein), and the reactivity of the induced anti-mimotope antibodies with the corresponding peptides and with MV was determined. The affinities of the antibodies with the homologous peptides ranged from 8.9 310 5 to 4.4 310 7 liters/mol. However, only one of the anti-mimotope antibodies cross-reacted with MV in an enzyme-linked immunosorbent assay and inhibited MV plaque formation. Coimmunization of mice with this mimotope and the T-helper epitope peptide induced an antibody response which conferred protection against fatal encephalitis induced following challenge with MV and with the structurally related canine distemper virus. These results indicate that peptide libraries can be used to identify mimotopes of conformational epitopes and that appropriate immunization with these mimotopes can induce protective antibody responses. Synthetic peptides have considerable potential value in biology and medicine as analytical and diagnostic reagents, therapeutics, and new vaccines. The use of peptides as vaccines offers several advantages over conventional vaccine strategies in terms of safety, cost, stability, and relative ease of production.Inaddition,peptidevaccineshavetheadvantagethatthey can be rationally designed to contain structures that stimulate appropriate immune responses (e.g., Th cells, B cells, and Tc cells) while avoiding structures that stimulate unwanted responses (e.g., suppressive effects). Although many antibodies are directed toward linear antigenic epitopes, it is likely that a significant proportion of humoral antibody responses to infectious agents are directed toward conformational epitopes. Thus, the identification of peptide structures that mimic linear epitopes from the primary amino acid sequence of a particular protein should be relatively straightforward but the identification of conformational B-cell epitopes is likely to be more problematic. Combinatorial synthetic peptide libraries, in which peptides are expressed on either the surface of filamentous bacteriophages or an insoluble solid phase, have been used to generate vastnumbersofdifferentpeptidesforbiologicalscreeningboth in vivo and in vitro. For example, the bacteriophage peptide libraries have been used to identify ligands for proteins such as streptavidin, integrins, and the urokinase cell surface receptor (3,9,17).Inaddition,theselibrarieshavebeenusedtoidentify a linear structural epitope on plasminogen-activating factor inhibitor type 1 (10), an epitope on human immunodeficiency virus type 1 gp120 which induces a neutralizing antibody to human immunodeficiency virus type 1 (11), and an epitope on herpes simplex virus type 1 (22). However, attempts to identify conformationalepitopesbyusingphagelibrarieshavemetwith only limited success (1, 6, 13). In this case, the peptide mimicking a discontinuous epitope recognized by a monoclonal antibody against Bordetella pertussis toxin, although reactive with the monoclonal antibody, could not induce antibodies which were reactive with the original antigen. Solid phase combinatorial peptide libraries have also been used to identify a number of biologically important peptide sequences such as enzyme inhibitors for human immunodeficiency virus protease (18) and trypsin (5), but the use of the solid phase libraries to generate mimics of conformational epitopes (mimotopes) has been very limited since the methodology was originally defined (7). It should be emphasized that mimotopes of conformational epitopes will not necessarily bear sequence identity with the primary amino acid sequence of the protein but will assume a conformation which mimics that of the epitope. Measlesvirus(MV)andthecloselyrelatedcaninedistemper

The aim of this study was to define the helper T cell epitopes on the haemagglutinin (H) of measles virus (MV) in BALB/c (H-2d) and TO (H-2s) mice. A panel of 55 synthetic peptides (15-mers, overlapping by five amino acids) representing 92.2% of the H protein were synthesized and tested for immunogenicity and ability to stimulate MV-primed lymphocytes in vitro. The results obtained show that mouse lymphocytes respond to defined regions of the H protein which differ according to mouse strain. Virus-primed lymphocytes from BALB/c mice responded in vitro to peptides 7, 38, 39 and 44 whereas lymphocytes from virus-primed TO mice responded only to peptide 39. When mice of both strains were immunized with the peptides, a number of peptides induced proliferative responses, showing that the T cell repertoire for epitopes on the H protein is broader than that following immunization with virus. In BALB/c mice, lymphocytes primed to peptides 37, 39, 40, 42 and 43 responded in vitro to MV and in TO mice, lymphocytes primed to peptides 14, 32, 39, 40 and 49 responded to the virus. Thus in both strains of mice peptide 39 behaved as a dominant T cell epitope following immunization with virus or peptides. When the results obtained experimentally were compared with sequences predicted to be T cell epitopes by a number of algorithms, the concordance was limited.