Possible influence of the mutant CCR5 Allele on vertical transmission of HIV-1.

A possible correlation between the rate of vertical transmission of HIV-1 and the presence of the defective HIV co-receptor gene delta 32ccr5 in the chromosomes of infants born to HIV-positive mothers was assessed. The prevalence and genotypic distribution of the delta 32ccr5 gene were studied in 451 uninfected and 225 HIV-1-infected adults and 79 children born to HIV-1-positive mothers in Austria (45 uninfected and 34 infected by vertical transmission). As expected in a Caucasian population, the delta 32ccr5 allele was found in uninfected Austrians at a frequency of 10% (17.3% heterozygotes and 1.3% delta 32ccr5/ delta 32ccr5 homozygotes, consistent with the expected Hardy-Weinberg distribution). The mutant allele frequency was 11.1% in uninfected children (17.8% heterozygotes, 2.2% homozygotes) and 9.6% in HIV-positive adults (19.1% heterozygotes but no delta 32ccr5/delta 32ccr5 homozygotes). Among the group of 34 vertically infected children, however, there were only two heterozygotes and no delta 32ccr5/delta 32ccr5 homozygotes, corresponding to a significantly reduced mutant allele frequency of 2.9% (P = 0.05 compared to HIV-negative children). These results suggest that CCR5/delta 32ccr5 heterozygous children are less susceptible to vertical transmission of HIV-1. The data also support the hypothesis that delta 32ccr5 homozygous individuals are resistant to HIV-1 infection.

Improved detection of respiratory syncytial virus in nasal aspirates by seminested RT-PCR.

A seminested RT-PCR for amplification of Respiratory syncytial virus (RSV)-RNA in nasal aspirates has been developed and used to test nasopharyngeal aspirates (NPAs) from 132 infants hospitalized with acute respiratory tract infections during winter epidemics. The results were compared with those obtained by virus isolation in tissue culture and antigen detection with an enzyme-linked immunosorbent assay (Ag-ELISA). RSV-RNA was detected by seminested RT-PCR in 57 of the 59 samples that were positive by virus isolation and/or ELISA, as well as in 25 of 73 samples negative by virus isolation and ELISA. Eighteen of these 25 samples were obtained from children older than one year of age, 17 of whom were experiencing reinfection, as indicated by the presence of preexisting serum RSV-IgG antibodies. These results indicate that seminested RT-PCR is more sensitive than conventional methods for the detection of RSV in patients experiencing reinfections and suggest that this assay might also be useful for rapid diagnosis of RSV infections in older people.