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  • 1
    ISSN: 1432-1076
    Keywords: Mother-to-child transmission ; HIV-1 ; IgA antibodies ; Peptide-ELISA ; Time-resolved fluoro-immunoassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The presence of specific IgA antibodies in sera from 25 infants born to HIV-1 seropositive mothers was investigated by peptide-ELISA and peptide time-resolved fluoro-immunoassay (TR-FIA). The infants had been monitored at different times after birth for clinical signs and/or symptoms of HIV-1 infection and for detection of HIV-1 in lymphocyte cultures. Serum samples had also been tested for HIV-1 IgG antibodies by commercial ELISA and Western blot and for p24 antigen. Eleven of 25 children were then identified as infected. IgA detection was performed after rProtein G treatment to remove interfering IgG. In the infected group, IgA specific antibodies to a synthetic peptide representing a highly conserved region of the transmembrane glycoprotein gp41 (env: 594–613) were detected in 27 (73%) out of 37 serum samples (9 of 11 children) by the peptide-ELISA test. IgA specific antibodies to the same peptide were found in 30 (81%) sera (9 of 11 children) by the peptide-TR-FIA. Specific HIV-1 IgA antibodies were detected as early as 2 months of age in serum samples from five out of seven children (71% sensitivity) using peptide-ELISA and from six out of seven (86% sensitivity) by peptide-TR-FIA. Conversely, IgA specific antibodies to HIV-1 were absent in two infected children as well as in the sera of all uninfected children tested during the follow up period. Since maternal IgA does not cross the placenta, IgA detection in the serum of the infant is indicative of HIV-1 infection. Indeed, the early demonstration of HIV-1 IgA antibodies in infected infants shows that both peptide-ELISA and peptide-TR-FIA can be used for an early diagnosis of HIV-1 infection.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0495
    Keywords: Groundwater ; Porous aquifer ; Heterogeneous ; Biological tracers ; Bacteriophage ; Fluorescent dye ; Naphthionate ; Electromagnetic survey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract This article presents an example of a tracing experiment using two bacteriophages, T7 and f1, and a fluorescent dye (naphthionate), in a saturated porous environment. The test field was equipped with an injection borehole and 22 sampling piezometers set in three concentric half-circles. The distribution of permeabilities and the thickness of the aquifer were indirectly determined by Radio-Magneto-Tellury (RMT, 12–240 kHz). The results reveal a good correlation between the distribution of permeabilities obtained by RMT and the breakthrough curves and speed of migration of all three tracers. The restitution levels are far superior (by two to three orders of magnitude) in the more permeable zones, as opposed to those observed in th piezometers situated in less permeable areas. The speed of migration of the biological tracers is much greater than that of the naphthionate. In the most extreme case, the T7 bacteriophage migrated about 3.15 times faster than the chemical solution. These results indicate that bacteriophages are able to travel considerable distances along permeable gravel channels. They may be used as biological tracers and as models for the migration of pathogenic viruses. The simultaneous use of tracing techniques and appropriate geophysical methods leads to a better knowledge of the hydrogeological parameters of the underground terrain. This combination allows for a better interpretation both of the speeds of migration and of the maximal concentrations of the tracers, and thus considerably increases the interpretability of hydrogeological impact studies.
    Type of Medium: Electronic Resource
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