Guadalupe Andreani

Lack of viral selection in human immunodeficiency virus type 1 mother-to-child transmission with primary infection during late pregnancy and/or breastfeeding

Mother-to-child transmission (MTCT) of human immunodeficiency virus type 1 (HIV-1) as described for women with an established infection is, in most cases, associated with the transmission of few maternal variants. This study analysed virus variability in four cases of maternal primary infection occurring during pregnancy and/or breastfeeding. Estimated time of seroconversion was at 4 months of pregnancy for one woman (early seroconversion) and during the last months of pregnancy and/or breastfeeding for the remaining three (late seroconversion). The C2V3 envelope region was analysed in samples of mother-child pairs by molecular cloning and sequencing. Comparisons of nucleotide and amino acid sequences as well as phylogenetic analysis were performed. The results showed low variability in the virus population of both mother and child. Maximum-likelihood analysis showed that, in the early pregnancy seroconversion case, a minor viral variant with further evolution in the child was transmitted, which could indicate a selection event in MTCT or a stochastic event, whereas in the late seroconversion cases, the mothers and childs sequences were intermingled, which is compatible with the transmission of multiple viral variants from the mothers major population. These results could be explained by the less pronounced selective pressure exerted by the immune system in the early stages of the mothers infection, which could play a role in MTCT of HIV-1.

Detection of HIV-1 dual infections in highly exposed treated patients

BackgroundGenetic characterization of HIV-1 in Argentina has shown that BF recombinants predominate among heterosexuals and injecting drug users, while in men who have sex with men the most prevalent form is subtype B.ObjectivesThe aim of this work was to investigate the presence of HIV dual infections in HIV-infected individuals with high probability of reinfectionStudy designBlood samples were collected from 23 HIV positive patients with the risk of reinfection from Buenos Aires. A fragment of the HIV gene pol was amplified and phylogenetic analyses were performed. Antiretroviral drug resistance patterns of all the sequences were analyzed.ResultsFive dual infections were detected with four patients coinfected with subtype B and BF recombinants and one patient was coinfected with two BF recombinants presenting different recombination patterns. Prolonged infection with a stable clinical condition was observed in the five individuals. Resistance mutation patterns were different between the predominant and the minority strains.ConclusionsOur results show that HIV dual infection can occur with closely related subtypes, and even with different variants of the same recombinant form in certain populations. Clinical observations showed neither aggressive disease progression nor impact on the resistance patterns in the dually-infected patients.

Inhibition of HIV-1 Replication in Human Monocyte- Derived Macrophages by Parasite Trypanosoma cruzi

Background Cells of monocyte/macrophage lineage are one of the major targets of HIV-1 infection and serve as reservoirs for viral persistence in vivo. These cells are also the target of the protozoa Trypanosoma cruzi, the causative agent of Chagas disease, being one of the most important endemic protozoonoses in Latin America. It has been demonstrated in vitro that co-infection with other pathogens can modulate HIV replication. However, no studies at cellular level have suggested an interaction between T. cruzi and HIV-1 to date. Methodology/Principal Findings By using a fully replicative wild-type virus, our study showed that T. cruzi inhibits HIV-1 antigen production by nearly 100% (p<0.001) in monocyte-derived macrophages (MDM). In different infection schemes with luciferase-reporter VSV-G or BaL pseudotyped HIV-1 and trypomastigotes, T. cruzi induced a significant reduction of luciferase level for both pseudotypes in all the infection schemes (p<0.001), T. cruzi-HIV (>99%) being stronger than HIV-T. cruzi (∼90% for BaL and ∼85% for VSV-G) infection. In MDM with established HIV-1 infection, T. cruzi significantly inhibited luciferate activity (p<0.01). By quantifying R-U5 and U5-gag transcripts by real time PCR, our study showed the expression of both transcripts significantly diminished in the presence of trypomastigotes (p<0.05). Thus, T. cruzi inhibits viral post-integration steps, early post-entry steps and entry into MDM. Trypomastigotes also caused a ∼60-70% decrease of surface CCR5 expression on MDM. Multiplication of T. cruzi inside the MDM does not seem to be required for inhibiting HIV-1 replication since soluble factors secreted by trypomastigotes have shown similar effects. Moreover, the major parasite antigen cruzipain, which is secreted by the trypomastigote form, was able to inhibit viral production in MDM over 90% (p<0.01). Conclusions/Significance Our study showed that T. cruzi inhibits HIV-1 replication at several replication stages in macrophages, a major cell target for both pathogens.

Epidemiological and Molecular Evidence of Two Events of Father-to-Child HIV Type 1 Horizontal Transmission

HIV-1 infection in children less than 15 years of age is mainly due to mother-to-child transmission. The aim of this work was to investigate molecular evidence to prove father-to-be horizontal transmission in two possible events of transmission. In the first event a boy was identified as HIV infected at 2-3 years of age. At the same time infection was confirmed in the father, while mother and siblings were negative. In the second event a girl was negative for HIV at age 1 and identified as HIV-1 infected at age 6. The fathers HIV infection was diagnosed in the same period while the mother was repeatedly negative. No evidence of sexual assault or transfusion was recorded in any case. Peripheral blood mononuclear cells were obtained from both fathers and children. After PCR amplification, the C2V3 region of the envelope gene and the region coding for amino acid 132 of p24 up to amino acid 40 of p7 of the gag gene were sequenced. Genetic distance measurements and phylogenetic tree analysis showed that in both cases the fathers and childs viral sequences were closely related. They were distinct when compared to Argentina sequences including sequences from the same geographic region. Epidemiological and molecular data strongly suggest that horizontal transmission had occurred, probably related to the close father-to-child contact.

Co-infection with Trypanosoma cruzi (Chagas' disease agent) decreases HIV-1 transcription in human placenta

Address: 1National Reference Centre for AIDS, Microbiology Department, School of Medicine, University of Buenos Aires, Buenos Aires, Argentina, 2Laboratory of Parasitology, Microbiology Department, School of Medicine, University of Buenos Aires, Buenos Aires, Argentina and 3Endocrinology Service, Clinic Biochemistry Department, Jose de San Martin Hospital, School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina * Corresponding author

Viral reactivation and pseudotype production in an in vitro superinfection system with two different strains of HIV-1

Summary.Viral production and variability of HIV-1 is normally high in vivo causing the necessary conditions for cellular superinfection. In order to evaluate the superinfection dynamics in vitro, H9HTLVIIIB cell line was superinfected with HIVMN. Superinfected cells showed nearly 50% cell mortality at day 1 post-superinfection (ps), which increased significantly up to day 4 ps. Superinfecting genome was detectable until day 10 ps. The superinfecting strain was found in the supernatant only on day 1 ps, but was recovered up to day 4 ps by coculture with non-infected cells. The existing strain (HIVHXB2) was recovered throughout the studied period. Pseudotype formation by the HIVHXB2 genome and envelope proteins of the superinfecting strain (HIVMN) was observed from day 1 to 6 ps. Viral production was increased by 1.7 LOG in superinfected cells from day 1 ps. Both viral production increase and pseudotype formation could be relevant for HIV pathogenesis in vivo.

Two cases of mother-to-child transmission of HIV and Trypanosoma cruzi in Argentina

Since numerous tropical pathogens lead to opportunistic infections in the context of the human immunodeficiency virus (HIV), coinfection could have significant effects on the course of HIV infection. 1 In this article we report two cases coinfected with HIV and Trypanosoma cruzi presenting unfavorable evolution despite correct treatment. Both patients were infected with both pathogens by mother-to-child transmission (MTCT) route, and both died due to a Klebsiella pneumoniae sepsis. Case 1: Child 1 was admitted to the Central Childrens Hospital in La Plata at age 1 month with respiratory difficulty and diarrhea. The patient was a preterm newborn with good weight for the gestational age, with no prenatal care. Both parents were illiterate, and were living with HIV for a year but without treatment, including during pregnancy. The father was an intravenous drug abuser, and had been incarcerated; a 2-year-old brother was HIV-negative but an elder sister had died of HIV/acquired immunodeficiency syndrome (AIDS). Chagas infection in the mother was probably congenital, since her mother emigrated from a high endemic zone. The child presented severe malnutrition and congenital heart disease (interventricular communication). The child started with shortness of breath and diarrhea with a 48-hour evolution, and also presented bilateral inguinal and cervical micropoliadenopaty, splenomegaly, thrush, hypoxemia, and opisthotonus position. Disturbances in the cerebrospinal fluid cell count became apparent and Streptococcus pneumoniae was cultivated. Therefore, the patient was received ceftriaxone at appropriate doses for meningitis treatment for ten days, and an erythrocyte transfusion was performed. Vaccination with DPT-HB-Hib and Salk was indicated. During hospitalization, he presented two episodes of seizures related with fever. Serologies for several pathogens were performed, and antibodies for T. cruzi, Toxoplasma gondii, Epstein-Barr virus (EBV), and HIV were detected. HIV infection was confirmed by polymerase chain reaction (PCR), and T. cruzi infection, by Microstrout (both infections were confirmed in at least two separate samples). Electroencephalography (EEG) and cerebral computed tomography (CT) were abnormal, with muscular hypertonia and opisthostonus, both bilateral clonus and positive Babinsky. The symptoms were interpreted as brain damage due to pneumococcocal meningoencephalitis. At the age of six months, he was released after 155 days in hospital. Then, at the age of 22 months, he presented with diarrhea and sepsis by K. pneumoniae with secondary dehydration. The patient died ten days later; he had been treated with zidovudine since delivery and for two months with combined HAART (lamivudine, stavudine, nelfinavir) and benzonidazol. Three resistance tests …

P20-11. Subtype B/BF recombinants multiple infection in patients with dual-transmission risks by means of Heteroduplex assay

Background The HIV-1 epidemics in Argentina presents a higher prevalence of subtype B in men having sex with men and of BF recombinant forms in injecting drug users and heterosexuals. Since little is known about HIV-1 dual infections in a population with double transmission risk, the aim of this study was to analyze the frequency of multiple infections in HIV (+) individuals from this at-risk group, by implementing the Heteroduplex assay (HAD) as a screening methodology.