rologie i - European Congress of Virology

5 th European Congress of VirologyObjectives: Immunity to Rubella virus is commonly determined by measuringspecific IgG (RV IgG). However, RV IgG results may be verydifferent and even discordant, depending on the assay used. Cell mediatedimmunity plays also a role in resistance to infection but is not routinelyinvestigated for diagnostic purposes. Our aim was to investigateboth humoral and cellular immunity of pregnant women with negativeor equivocal RV IgG titers before and after the recommended post partumvaccination.Methods: 86 patients were included in the study. In the pre vaccinationperiod, humoral immunity was investigated with 4 RV IgG ELISA assays, awestern blot and a cell mediated immunity test (based on the − interferonresponse after stimulation by rubella antigens). In the post vaccinal period,measuring rubella specific IgM and RV IgG avidity allowed us to determinewhether a primary or a secondary immune response occurred.Results: Patients, who initially had negative RV IgG but above half thecut off of the assay, had positive RV IgG E1 antibodies, positive cellmediated immunity and experienced a secondary immune response aftervaccination (44/86). Patients with RV IgG below half the cut off of theassay had negative RV IgG E1 antibodies, negative cell mediated immunityand experienced a primary immune response after vaccination (42/86).Conclusion: These results indicate that several individuals may beimmune despite negative RV IgG. This could lead us to reduce the sensitivitythreshold of the rubella serologic assays, with respect to theirdiagnostic accuracy.REF O73A delay in the maternal antibody response to human cytomegalovirus(HCMV) gH/gL/pUL128 130 131 complex is associated with virustransmission to the fetusDaniele LILLERI 1,2 , Anna KABANOVA 2 , Maria Grazia REVELLO 1 ,Elena PERCIVALLE 1 , Antonella SARASINI 1 , Emilia GENINI 1 ,Federica SALLUSTO 2 , Antonio LANZAVECCHIA 2 , Davide CORTI 2 ,Giuseppe GERNA 11 Fondazione IRCCS Policlinico San Matteo, Pavia, ITALY; 2 Institute forResearch in Biomedicine, Bellinzona, SWITZERLANDPrimary HCMV infection during pregnancy is associated with a high riskof virus transmission to the fetus. Serial serum samples from 43 HCMVtransmitter (T) and non transmitter (NT) pregnant women with primaryHCMV infection were analyzed for neutralizing antibodies against HCMVglycoprotein complexes to identify correlates of HCMV transmission. Inthis study, we report that early detection of HCMV neutralizing antibodiesdirected against the pentameric complex gH/gL/pUL128 131 and, in particular,to the UL128 131 gene products appears to be associated with alower rate of HCMV transmission from the mother to the fetus. This wasshown by the finding that NT mothers exhibit an earlier antibody responseto different antigenic sites of the pentamer as compared to T mothers. Thisassociation was found to be consistent with the lower number of neutralizationsites recognized by T as compared to NT women at the 1st andthe 2nd month post infection onset. Furthermore, anti pentamer antibodiesdisplay an in vitro inhibition of cell to cell spreading and virus transferto leukocytes. The biological relevance of anti pentamer antibodies hasbeen in parallel highlighted by the finding that antibodies to HCMV gBare produced by NT and T mothers with the same kinetics and in comparableamounts. Taken together, these findings indicate that: i) the pentamercomplex is a major target of the antibody mediated maternal immunity;ii) T women elicit a lower neutralizing antibody response in the first 2months after onset of infection as compared to NT women.REF 074Development of a multiplex PCR approach for detection of dual infectionsand recombinants involving HIV variantsPierre CAPPY, Fabienne DE OLIVEIRA, Marie GUEUDIN, JeanChristophe PLANTIERRouen University Hospital, Rouen, FRANCEBackground: The high genetic diversity of HIV necessitates consistentattention to diagnostic tools and patient follow up. Due to the co circulationof different HIV types and groups, dual infections (DIs) and recombinants(Rec) have been described, which may hinder diagnosis and therapeuticmanagement.Methods: We designed 2 multiplex PCRs (mPCRs) coupled to capillaryelectrophoresis: MMO2, targeting 2 genes for the screening of HIV M+Oand M+2 DIs, and MMO, targeting 5 genes for the detection of HIV M+ODIs and HIV MO Rec. mPCRs were assessed on DNA and RNA extractsfrom HIV M, O and 2 virus cultures, then on DNA and RNA mixtures,simulating DIs. They were finally assessed on material from clinical monoinfection and from patients presenting with an HIV M+O or an HIV MOinfection.Results: In vitro samples. For MMO2, the overall sensitivity was 88% onDNA and 100% on RNA, along with a specificity of 100%. For MMO,the sensitivity was 100%, along with a specificity of 94% on DNA and100% on RNA. On simulated DIs, both mPCRs correctly detected 90%and 100% of DNA and RNA samples respectively. Clinical samples. ThemPCRs specificity was 100%, with a global sensitivity of 87% and 91%for MMO2, and 60% and 81% for MMO, on DNA and RNA respectively.Finally, both mPCRs were able to detect 4 out of 6 DIs on RNA,2 out of 2 DIs on DNA for MMO2, and 2 out of 2 MO Rec on RNAfor MMO.Conclusions: Altogether, on in vitro and clinical samples, MMO2 turnsout to be an excellent screening tool to detect M+2 and M+O DIs, andMMO to detect both MO DIs and MO mosaic patterns.REF O75Clinical Evaluation of BioPlex 2200 HIV Ag Ab: An AutomatedScreening Method Providing Discreet Detection of HIV 1 p24, HIV1 Antibody, and HIV 2 AntibodyFrançois SIMON 1 , Maud SALMONA 1 , Sarah MAYLIN 1 , LucGUERRIER 2 , Bill LINK 31 AP HP Hôpital Saint Louis, Laboratoire de virologie, Paris, FRANCE;2 Bio Rad Laboratories, Inc., Marnes La Coquette, FRANCE; 3 Bio RadLaboratories, Inc., Hercules, USABackground/Purpose: To assess the clinical sensitivity/specificity of theBioPlex 2200 HIV Ag Ab assay. The study was performed at the laboratoryof Virology of St. Louis Hospital, Paris.Methods: The BioPlex 2200 HIV Ag Ab assay uses multiplex flow IA todetect p24 Ag, HIV 1 Ab (Groups M/O) and HIV 2 Ab in a single reactionvessel using a mixture of 4 dyed bead populations. Each populationis coated with a different HIV Ag or p24 Ab, and results can be reportedindividually. Ab reactive specimens can be typed as HIV 1 or HIV 2. Specimenswith similar levels of HIV 1/2 Ab reactivity are reported as reactiveundifferentiated. The study included 1505 prospective fresh samples fromhospitalized patients, 420 stored samples from infected patients with HIV1 (different B or non B/CRF subtypes incl. 8 HIV 1 Grp O), a panel of 15samples collected during Primary HIV infection (PHI)/86 HIV 2 samples.S68 Virologie, Vol 17, supplément 2, septembre 2013