Ch. Rouzioux

How much would the safety of blood transfusion be improved by including p24 antigen in the battery of tests

BACKGROUND: Because p24 antigen may be detectable during seroconversion, before antibodies, some of the infected blood undetected by antibody screening could be identified through antigen screening.

The Frequency of HIV-Specific Interferon-γ–Producing CD8 T Cells Is Associated with Both Age and Level of Antigenic Stimulation in HIV-1–Infected Children

Ex vivo interferon (IFN)- gamma -producing CD8 T cells specific for human immunodeficiency virus (HIV) Env, Gag, and Pol antigens were measured in the peripheral blood of 55 children not receiving highly active antiretroviral therapy (HAART) and 70 children receiving HAART. In children not receiving HAART, the frequency of HIV-specific IFN- gamma -producing CD8 T cells was positively correlated with age and was not associated with plasma viral load or CD4 T cell levels. In children receiving HAART, the frequency of HIV-specific IFN- gamma -producing CD8 T cells was directly correlated with plasma viral load, and its association with age remained significant. In conclusion, the frequency of HIV-specific IFN- gamma -producing CD8 T cells in children is primarily determined by both age and plasma viral load.

Le diagnostic de l'infection à VIH chez le nouveau-né, en Europe et dans les pays en voie de développement

Diagnosis of HIV infection in newborn infants of seropositive mothers is essential to initiation of treatment. The risk of vertical transmission is estimated at around 20% in Europe and the U.S. and 25% in Africa where it is increased by breast feeding. The risk is known to depend on the clinical status of the mother. Virological analyses by the French Cohort Study suggest that around 30% of the infections occur in utero late in pregnancy while 65% occur on the day of delivery. Fetomaternal blood exchanges and maternal secretions in the birth canal are believed to lead to infection. Diagnosis of infants infected in utero may be based on specimens taken at birth but later testing is necessary for infants infected during delivery or breast feeding. The risk of transmission during breast feeding is estimated at 5-7%. The presence of maternal antibodies prevents use of the usual serological tests in newborns. The technique of viral culture which may be applied to any strain of HIV-1 or HIV-2 allows diagnosis of most positive cases within 15 days. The sensitivity of the test increases from 40% at birth to over 95% at 2 months. The polymerase chain reaction (PCR) technique applied to DNA is possibly as sensitive as viral culture. Laboratory trials of PCR applied to RNA have given promising results. The lack of consensus on the criteria for considering a diagnostic result positive is at the origin of observed differences in sensitivity and specificity of methods of PCR and viral culture developed in different laboratories. All positive results should be confirmed on a second independently obtained sample. To diagnose noninfection may require 2 or 3 negative tests after the first week of life. After 18 months the same methods of serodiagnosis utilized in adults may be used. Technical and financial difficulties prevent widespread testing of newborns in many developing countries.

La transmission materno-fœtale du VIH

La transmission du virus de l’immunodeficience humaine (VIH1) de la mere a l’enfant, estimee a 20 % en l’absence de traitement antiretroviral preventif, peut survenir a differentes etapes de la grossesse : in utero, dans les semaines precedant l’accouchement, dans un tiers des cas, intra partum, au moment de l’accouchement, dans deux tiers des cas. L’objectif de cet article est de faire le point sur les mecanismes virologiques impliques dans la transmission materno-fœtale du VIH. Bien que les cellules trophoblastiques semblent pouvoir etre infectees, le placenta ne semble pas etre un site de replication tres actif du virus. L’hypothese d’une transmission virale a la fin de la grossesse plaide plutot en faveur d’un transfert de cellules maternelles infectees lors d’echanges sanguins fœto-maternels importants. Au moment de l’accouchement, il y a cumul des risques et exposition importante de l’enfant a l’infection virale. En effet, les echanges sanguins fœto-maternels se poursuivent et l’enfant est directement expose au sang maternel ainsi qu’aux secretions cervico-vaginales contenant des particules virales libres ou des cellules infectees lors de son passage dans la filiere genitale. A l’evidence, plusieurs mecanismes interviennent dans cette transmission, qui apparait multifactorielle. Trois grands groupes de facteurs ont ete identifies : les facteurs lies au virus, les facteurs maternels et les facteurs lies a la susceptibilite genetique de l’enfant. L’identification de ces parametres a permis de proposer des schemas therapeutiques qui permettent de reduire cette transmission.

Insectes hématophages et virus de l'immuno-déficience humaine (VIH): étude de la survie du VIH chez Triatoma infestans (KLUG 1884)

We investigated whether Triatoma infestans could shelter the HIV1 virus. For this purpose we measured the survival time of the virus in the alimentary tract. Retrovirus activity was demonstrated in the lymphocyte co-culture supranatant by dosing the p24 antigen and the reverse transcriptase activity. The virus has been found alive up to the 7th day after the last infectious meal of the insect.