Seroprevalence of hepatitis B and C infection among the HIV-positive population in Abuja, Nigeria

BACKGROUND

In Nigeria, it is estimated that 3.6% of the population were living with Human immunodeficiency virus in 2009, and the country had the world's second highest number of HIV/AIDS related deaths after South Africa. Viral hepatitis is also a major public health concern as hepatitis B virus (HBV) afflicts an estimated 350 million people, and hepatitis C virus (HCV) affects 150 million people worldwide.

OBJECTIVES

We conducted a retrospective study of HBV and HCV seroprevalence among Nigerian population coming to our clinic in Abuja and receiving HIV/AIDS treatment.

METHODS

In this cohort study, we collected medical data from 443 HIV-positive patients between September 2010 and May 2011. Standard enzyme immunoassays were used to determine the serological prevalence of hepatitis B (HBsAg) and C (anti-HCV antibody) among HIV-positive individuals.

RESULTS

Among the HIV/AIDS positive individuals, we found that 35 patients were infected with hepatitis B virus (7.9%), 10 with hepatitis C virus (2.3%) and 3 with both hepatitis B and C viruses (0.7%). The overall hepatitis-HIV prevalence is 10.8%. The majority of the population infected was under 39 years of age (55%) and the same proportion of males and females was observed in all the studied categories (HIV, HIV + hepatitis B and/or C). Remarkably, an overall lower CD4 count was seen in the co-infected population (205 cells/µl versus 243 cells/µl), with the lowest seen for the triply infected individuals (97 cells/µl).

CONCLUSIONS

Our findings underscore the importance of screening for hepatitis B and hepatitis C viruses in the HIV-infected population in developing countries, and particularly in sub-Saharan Africa, where the epidemics are still growing.

Intracellular rate-limiting steps of gene transfer using glycosylated polylysines in cystic fibrosis airway epithelial cells

To identify the intracellular barriers to efficient gene transfer, we studied the intracellular trafficking of biotinylated plasmid DNA complexed with either fluorescein-conjugated lactosylated or mannosylated polylysine by confocal microscopy. Both are known to be taken up by cystic fibrosis airway epithelial cells (SigmaCFTE29o- cells), but their gene transfer efficiencies differ markedly: lactosylated polylysine is the most efficient glycosylated polylysine while mannosylated polylysine is quite inefficient for gene transfer. Mannosylated complexes appeared to stay longer in endosomes labeled by anti-transferrin receptor antibody than lactosylated complexes (from 30 min to 3 h and from 10 min to 30 min, respectively). At 24 h, higher percentages of mannosylated than lactosylated complexes were localized inside lysosomes labeled by anti-LAMP-1 antibody (41.8 +/- 6.6% versus 19.8 +/- 5.2%, respectively, P < 0.05). Between 30 min and 8 h, complexes reached the nuclei labeled by anti-lamin A/C antibody and no difference was observed between the nuclear amounts of mannosylated and lactosylated complexes. However, as analyzed by a nuclease S1 transcription assay, initiation of transcription was prevented when plasmid DNA was complexed to mannosylated polylysine. Our results indicate that the major limiting steps for mannosylated versus lactosylated polylysine transfer of plasmid DNA are delayed exit from endosomes, high accumulation in lysosomes and limited transcription of the complexed plasmid DNA.

A role of the C-terminal part of p44 in the promoter escape activity of transcription factor IIH

The p44 subunit plays a crucial role in the overall activity of the transcription/DNA repair factor TFIIH: on the one hand its N-terminal domain interacts with and regulates the XPD helicase (, ); on the other hand, as shown in the present study, it participates with the promoter escape reaction. Mutagenesis along with recombinant technology using the baculovirus/insect cells expression system allowed us to define the function of the two structural motifs of the C-terminal moiety of p44: mutations within the C4 zinc finger motif (residues 291-308) prevent incorporation of the p62 subunit within the core TFIIH. Double mutations in the RING finger motif (residues 345-385) allow the synthesis of the first phosphodiester bond by RNA polymerase II, but prevent its escape from the promoter. This highlights the role of transcription factor IIH in the various steps of the transcription initiation process.

Mutations in XPB and XPD helicases found in xeroderma pigmentosum patients impair the transcription function of TFIIH

As part of TFIIH, XPB and XPD helicases have been shown to play a role in nucleotide excision repair (NER). Mutations in these subunits are associated with three genetic disorders: xeroderma pigmentosum (XP), Cockayne syndrome (CS) and trichothiodystrophy (TTD). The strong heterogeneous clinical features observed in these patients cannot be explained by defects in NER alone. We decided to look at the transcriptional activity of TFIIH from cell lines of XP individuals. We set up an immunopurification procedure to isolate purified TFIIH from patient cell extracts. We demonstrated that mutations in two XP-B/CS patients decrease the transcriptional activity of the corresponding TFIIH by preventing promoter opening. The defect of XPB in transcription can be circumvented by artificial opening of the promoter. Western blot analysis and enzymatic assays indicate that XPD mutations affect the stoichiometric composition of TFIIH due to a weakness in the interaction between XPD-CAK complex and the core TFIIH, resulting in a partial reduction of transcription activity. This work, in addition to clarifying the role of the various TFIIH subunits, supports the current hypothesis that XP-B/D patients are more likely to suffer from transcription repair syndromes rather than DNA repair disorders alone.