The effect of tuberculin skin testing on viral load and anti-mycobacterial immune responses in HIV-1-infected Ugandan adults.

OBJECTIVE: To determine whether tuberculin skin testing (TST) is associated with an increase in human immunodeficiency virus (HIV) viral load, and to examine the effect of TST on anti-mycobacterial immune responses. DESIGN: A nested cohort study of HIV-1-infected adults. METHOD: Forty-two participants (21 TST-positive and 21 TST-negative) from a larger cohort were recruited to the study. Blood was collected for CD4+ T-cell count, whole blood was cultured, and plasma saved for viral load. These measurements were taken before, 3 days after, 3 months after, and 3 months plus 3 days after TST. Cytokine responses to culture filtrate proteins (CFP) of Mycobacterium tuberculosis and phytohaemagglutinin (PHA) were examined in the whole blood assay. RESULTS: Twenty-nine participants attended all four visits. No statistically significant change in viral load, CD4+ T-cell count, or cytokine response to PHA was observed at any visit. However, TST was associated with a transient increase in the interferon-gamma response to CFP and a lasting increase in the interleukin-5 response to CFP. CONCLUSION: There appeared to be a systemic effect of TST on the anti-tuberculosis immune response.

Aetiology of sexually transmitted infections and response to syndromic treatment in southwest Uganda.

OBJECTIVE: To determine the aetiology of genital ulcers and discharges in rural south western Uganda and to assess response to syndromic treatment. METHOD: A longitudinal, prospective study using laboratory testing and questionnaires to evaluate 561 adult men and women presenting with clinically verified genital ulcers, urethral, or vaginal discharge at a general outpatient clinic and two health centres between December 1999 and July 2001. RESULTS: One third of patients had genital ulcers and two thirds discharges. There was good response to treatment in 461/508 patients (90.7%). Herpes simplex virus type 2 was found in 95/217 (43.8%) genital ulcers. In 24.1% of ulcer cases there was also a genital discharge. HIV seropositivity was high in ulcer cases (63.2%), with significantly more HSV2 and secondary bacterial infection than in seronegative cases. Neisseria gonorrhoeae was found in 135/204 (66.2%) male genital discharges. Female genital discharges were mostly associated with bacterial vaginosis (36.1%), Trichomonas vaginalis (18.9%), and candidiasis (18.6%). CONCLUSIONS: The aetiological pattern of STI syndromes reported will help inform revision of national STI guidelines. The importance of herpes simplex virus type 2, the variation in causes of genital ulcers according to HIV serostatus, the high frequency of multiple infections and secondary bacterial contamination of genital ulcers are notable. These results help explain the lack of effect of an STI intervention on HIV incidence in a recent trial in this area.

Genetic diversity between hepatitis G virus isolates: analysis of nucleotide variation in the NS-3 and putative 'core' peptide genes.

Significant variation was found, between 46 isolates of hepatitis G virus (HGV), following direct sequencing of subgenomic PCR fragments from either or both the NS-3 and putative 'core' peptide. Nucleotide sequences of most HGV NS-3 fragments varied by 10-30% and of most putative 'core' peptide fragments by 2-20%. HGV was therefore shown to be much less variable than hepatitis C virus (HCV) and pairwise comparisons of HGV sequences demonstrated a single distinct distribution of evolutionary distances. Construction of phylogenetic trees, bootstrap analysis and calculation of mean distances between possible subtypes also indicated one level of variation between HGV NS-3 and putative 'core' peptide sequences, and the suggested degree of variation between isolates was similar to that between HCV subtypes. No evidence for clustering of sequences into multiple subtypes or genotypes was found. Although very small subgenomic fragments of HCV are indicative of the viral genotype it seems that the assignment of genetic groups is not possible for HGV using such small subgenomic fragments. The relatively limited genetic variation observed in HGV may reflect a relatively low level of host selection pressure stemming from the low level of host immunity stimulated by this virus.

Predicted secondary structure of the hepatitis G virus and GB virus-A 5'untranslated regions consistent with an internal ribosome entry site.

We describe comparative sequence analysis of 20 isolates of the recently discovered hepatitis G virus (HGV) and propose a model of the RNA secondary structure at the 3' end of the 5' untranslated region (UTR) of this virus. A single AUG starting at nucleotide position 552, which was in-frame and continuous with the putative polyprotein, was conserved in all 20 isolates and appeared to be the most likely site for the initiation of polyprotein synthesis. This consensus AUG was 14 amino acid residues upstream of a sequence with identity to the envelope protein E1 of hepatitis C virus (HCV), but the actual function of this N-terminal peptide of HGV is still not certain. None of the isolates encoded a sequence with similarity to the nucleocapsid protein of any known virus. The RNA secondary structure of the fragment under study was determined using thermodynamic modelling and validated using the results of comparative sequence analysis. Further support for the model was gained from the prediction of significant sequence and structural homology in the RNA secondary structure of the complete 5'-UTR of GB virus-A (GBV-A). A possible mechanism for translation initiation in HGV and GBV-A was suggested by the identification of features in common with the internal ribosome entry sites (IRESs) of HCV and picornaviruses.

Influenza virus pyrogenicity: central role of structural orientation of virion components and involvement of viral lipid and glycoproteins.

Ultraviolet light-inactivated, non-infectious influenza virus is pyrogenic; virion components are probably responsible for this pyrogenicity. To try to identify the pyrogenic component, influenza virions were disrupted with either bromelain or sodium deoxycholate (DOC). Treatment of infectious virions with bromelain, under conditions that removed the surface glycoproteins (spikes), destroyed their pyrogenicity. The supernatant, containing non-aggregated and modified glycoproteins, was also non-pyrogenic. Disruption of virions with DOC considerably reduced pyrogenicity; however, some was retained by the sub-viral cores. Viral nucleoprotein and matrix protein, purified from the supernatant, were non-pyrogenic. Aggregated stellate clusters of surface glycoproteins separated on sucrose gradients were pyrogenic in half of numerous tests performed with different batches of material. Treatment of virus with ether resulted in complete loss of pyrogenicity. Liposomes made from extracted viral lipid were non-pyrogenic. In contrast, virosomes made from the viral lipid and the aggregated stellate clusters of surface glycoproteins were pyrogenic. Hence, optimum pyrogenicity depends upon the integrity of the virus particle, but haemagglutinin and/or neuraminidase appear essential, and lipid may be involved.

Hepatitis G virus infection: clinical characteristics and response to interferon.

A new member of the Flaviviridae family has recently been cloned and completely sequenced. The new virus, tentatively named hepatitis G virus (HGV) and known to be closely related to GB virus C (GBV-C), is transmitted by blood and blood products, intravenous drug use and other behaviour associated with a high risk of parenteral exposure to blood. The association of the virus with hepatitis is demonstrated by the presence of raised liver transaminase (alanine aminotransferase, ALT) levels in patients infected with HGV in the absence of other identifiable causes of hepatitis. No patient sera from groups exposed to blood and blood products were found to be positive when tested for the presence of GBV-A or GBV-B sequences, two other recently described flaviviruses. Forty-five per cent of the HGV-infected patients investigated had normal ALT suggesting the existence of a normal carrier state. Persistent infection of up to 13 years duration was observed. Co-infection with hepatitis B or hepatitis C viruses (HBV and HCV) was commonly seen presumably because of shared risk factors. None of five patients with fulminant hepatic failure was positive for HGV infection. The virus is sensitive to interferon-alpha, but sustained responses were not seen with the treatment regimens used for HBV and HCV. Viral titres increased during immunosuppression following liver transplantation and the higher levels of viraemia were in one case accompanied by elavated ALT. Whether HGV (GBV-C) replicates in the liver in some or all cases remains to be established. Preliminary data suggest that it is present within peripheral blood lymphocytes.

Severe exacerbation of liver disease during pregnancy in a thalassemic GBV-C/HGV-positive patient and neonatal hepatitis in offspring.

The case of a young woman with GB virus C/hepatitis G virus (GBV-C/HGV) infection and with a severe exacerbation of chronic hepatitis of unknown etiology during pregnancy is described. In the offspring, severe neonatal hepatitis with subsequent mild chronic liver disease of at least 16-month duration was followed by the development of antibodies to the envelope protein (E2) of GBV-C/HGV, suggesting that the child was recovering from GBV-C/HGV infection. There was an improvement in clinical and biochemical parameters in the mother following delivery and alpha-interferon therapy was associated with a transient biochemical response.