942
SIR,-Alterations in the nucleotide sequence of the HIV genome frequent, and the variability is especially pronounced in the env reading frame. HIV gag and pol reading frames seem to be more highly conserved.l DNA and protein sequencing of isolates from are
diverse geographical regions indicate different subgroups of HIV-1-a homogenous North American group and a heterogeneous African group.2-4 There are reports indicating that some isolates from Africa are highly cytopathic and unusually infectious. These reports and data on HIV indeterminate serological results suggest the existence of variants distinct from previously characterised strains of HIV-1 (and HIV-2). Previous attempts in our laboratory to amplify proviral DNA from Ethiopian HIV-1infected patients with the polymerase chain reaction (PCR) were hampered by the use of primers in insufficiently conserved segments of the HIV-1 genome.6.7 Therefore, new primers were produced, based on conserved gag, pol, and env sequences in several North American and African HIV-1 isolates. Of eight Ethiopian samples of peripheral blood mononuclear cells from patients with AIDS that were tested by PCR, all reacted with the new gag primers; seven reacted with the pol primers and four with the env primers. Direct DNA sequencing from the PCR products in the gag reading frame from the eight Ethiopian and from five Swedish HIV-1 strains showed that the Ethiopian, but not the Swedish, strains have four common sites of nucleotide sequence changes in the amplified gag p7 region, when compared with a 1990 HIV-1 consensus sequence. The specific nucleotide changes are all A-T to G-C transitions or the reverse. An Ethiopian HIV-1 consensus DNA sequence was derived from the sequenced strains. Translation of the Ethiopian HIV DNA sequences to protein sequences, and comparison with a HIV-1 consensus, showed one substitution of a glycine to a serine and one lysine to an arginine, while the other two changes were conservative. These changes are unique for the Ethiopian strains, and set them apart from all other HIV-1 strains sequenced to date. A possible strain selection bias during cultivation of the virus8 is ruled out, since the DNA sequencing was done directly with amplified DNA isolated from the peripheral blood cells of the patients. Thus, the Ethiopian strains can be considered as constituting a new subtype of HIV-1. The characteristics of this subtype, in particular regarding infectiousness and pathogenic effect, remain to be established.
Supported by the Swedish Agency for Research and Education Developing Countries (SAREC).
in
Department of Biology, Addis Ababa University
SEYOM AYEHUNIE
Department of Virology, Central Microbiological Laboratory, Stockholm County Council
BO JOHANSSON ANDERS SÖNNERBORG
National Public Health Institute, Helsinki, Finland
MIKA SALMINEN
National Research Institute of Health, Addis Ababa
DEBRE-WORK ZEWDIE
Department of Infectious Diseases, Roslagstull Hospital, Karolinska Institute
1. Clavel
Breastfeeding and urinary-tract infection SIR,-As a reaction to a Lancet editorial on case-control studies. Piscane et al presented such a study suggesting a protective effect of breastfeeding against urinary-tract infection (UTI) in infants.’ W: have done a prospective study on a more defmed patient population of 81 consecutive children aged 21to 6 years (median 0.8 years With their first known attack of acute pyelonephritis.2 The 77 controls were matched for age, sex, and living area. Complete breastfeedmg was significantly briefer among the pyelonephritis patients thaa among the controls, as our questionnaire on medical histor, (p
SIR,-Alterations in the nucleotide sequence of the HIV genome frequent, and the variability is especially pronounced in the env reading frame. HIV gag and pol reading frames seem to be more highly conserved.l DNA and protein sequencing of isolates from are
diverse geographical regions indicate different subgroups of HIV-1-a homogenous North American group and a heterogeneous African group.2-4 There are reports indicating that some isolates from Africa are highly cytopathic and unusually infectious. These reports and data on HIV indeterminate serological results suggest the existence of variants distinct from previously characterised strains of HIV-1 (and HIV-2). Previous attempts in our laboratory to amplify proviral DNA from Ethiopian HIV-1infected patients with the polymerase chain reaction (PCR) were hampered by the use of primers in insufficiently conserved segments of the HIV-1 genome.6.7 Therefore, new primers were produced, based on conserved gag, pol, and env sequences in several North American and African HIV-1 isolates. Of eight Ethiopian samples of peripheral blood mononuclear cells from patients with AIDS that were tested by PCR, all reacted with the new gag primers; seven reacted with the pol primers and four with the env primers. Direct DNA sequencing from the PCR products in the gag reading frame from the eight Ethiopian and from five Swedish HIV-1 strains showed that the Ethiopian, but not the Swedish, strains have four common sites of nucleotide sequence changes in the amplified gag p7 region, when compared with a 1990 HIV-1 consensus sequence. The specific nucleotide changes are all A-T to G-C transitions or the reverse. An Ethiopian HIV-1 consensus DNA sequence was derived from the sequenced strains. Translation of the Ethiopian HIV DNA sequences to protein sequences, and comparison with a HIV-1 consensus, showed one substitution of a glycine to a serine and one lysine to an arginine, while the other two changes were conservative. These changes are unique for the Ethiopian strains, and set them apart from all other HIV-1 strains sequenced to date. A possible strain selection bias during cultivation of the virus8 is ruled out, since the DNA sequencing was done directly with amplified DNA isolated from the peripheral blood cells of the patients. Thus, the Ethiopian strains can be considered as constituting a new subtype of HIV-1. The characteristics of this subtype, in particular regarding infectiousness and pathogenic effect, remain to be established.
Supported by the Swedish Agency for Research and Education Developing Countries (SAREC).
in
Department of Biology, Addis Ababa University
SEYOM AYEHUNIE
Department of Virology, Central Microbiological Laboratory, Stockholm County Council
BO JOHANSSON ANDERS SÖNNERBORG
National Public Health Institute, Helsinki, Finland
MIKA SALMINEN
National Research Institute of Health, Addis Ababa
DEBRE-WORK ZEWDIE
Department of Infectious Diseases, Roslagstull Hospital, Karolinska Institute
1. Clavel
Breastfeeding and urinary-tract infection SIR,-As a reaction to a Lancet editorial on case-control studies. Piscane et al presented such a study suggesting a protective effect of breastfeeding against urinary-tract infection (UTI) in infants.’ W: have done a prospective study on a more defmed patient population of 81 consecutive children aged 21to 6 years (median 0.8 years With their first known attack of acute pyelonephritis.2 The 77 controls were matched for age, sex, and living area. Complete breastfeedmg was significantly briefer among the pyelonephritis patients thaa among the controls, as our questionnaire on medical histor, (p
