Biomedical subjects

Susanna L Lamers

Publications and source records attributed to Susanna L Lamers.

3 recordsLinked to original sources

PubMed2026

Pre-Antiretroviral Therapy Vertical HIV-1 Transmission Risk in Uganda Varies by Sex of Child and Maternal Viral Subtype.

We analyzed perinatal transmission in a pre-antiretroviral therapy Ugandan cohort by maternal human immunodeficiency virus type 1 subtype and infant sex in 131 mother-child pairs. Among all children, if the mother was infected with subtype A there was a nearly 3-fold increased risk of perinatal transmission compared with subtype D (risk ratio [RR], 2.96 [95% confidence interval (CI), 1.46-6.01]; P = .008). When stratifying infants by both sex and maternal subtype, significantly more female (56.3% [9 of 16]) than male (9.1% [1 of 11]) infants born to mothers with subtype A were infected (RR, 6.19 [95% CI, .91-42.12]; P = .02). In contrast, among infants born to mothers with subtype D, transmission rates were comparable across sex (RR, 1.59 [95% CI, .57-4.41]; P = .39).

Humans↗

PubMed2005

Phylodynamic analysis of human immunodeficiency virus type 1 in distinct brain compartments provides a model for the neuropathogenesis of AIDS.

"Phylodynamic" analysis combines various statistical procedures that can be used to correlate the epidemiological and evolutionary behavior of viral pathogens with the immune system of the host. We utilized this approach to examine human immunodeficiency virus type 1 (HIV-1) gp120 envelope DNA sequences (V1, V2, and V3) isolated from different brain compartments of a T-cell-depleted patient diagnosed with severe HIV-associated dementia at the time of death. In agreement with previous reports, phylogenetic analysis showed distinct virodemes but also revealed a significant amount of viral gene flow among different brain compartments. Local-molecular-clock analysis showed that HIV-1 meninges and temporal lobe subpopulations evolve about 30 and 100 times faster, respectively, than the other viral populations in the brain. However, maximum likelihood codon-based substitution models did not detect any site under significant positive selective pressure, and the main cause of HIV-1 genetic variation appeared to be random genetic drift. Therefore, the higher evolutionary rate in the meninges and temporal lobe could be due to an enhanced infection/expansion rate of macrophages as a consequence of the immune system failure. In conclusion, in this case study, viral infection in the brain progressed with a nonspecific genetic evolution, recurrent migration events, and an expansion of macrophage-tropic sequences. The data suggest that after immune failure newly produced viral variants, which would be rapidly cleared under normal conditions, begin to productively infect macrophages in a "self-amplifying" cycle of infection/inflammatory response that could be at the origin of HIV-associated dementia.

AIDS Dementia Complex↗

PubMed2002

Increased replication of non-syncytium-inducing HIV type 1 isolates in monocyte-derived macrophages is linked to advanced disease in infected children.

Non-syncytium-inducing (NSI) strains of HIV-1 prevail among most infected children, including pediatric patients who develop advanced disease, severe immune suppression, and die. A study was designed to address the hypothesis that genotypic and/or phenotypic markers can distinguish NSI viruses isolated during early infection from NSI viruses found in advanced disease. Primary HIV-1 isolates, which were obtained from 43 children, adolescents, and adults who displayed a cross-section of clinical disease and immune suppression but were untreated by protease inhibitor antiretroviral therapy, were characterized for replication phenotype in different cell types. Most individuals (81%) harbored NSI viruses and almost half had progressed to advanced disease or severe immune deficiency. About 51% of NSI isolates produced low levels of p24 antigen (median, 142 pg/ml) in monocyte-derived macrophages (MDMs), 31% produced medium levels (median, 1584 pg/ml), and 17% produced high levels (median, 81,548 pg/ml) (p < 0.001). Seven of eight syncytium-inducing isolates also replicated in MDMs and displayed a dual-tropic phenotype that was associated with advanced disease. Replication of NSI viruses in MDMs varied as much as 100- to 1000-fold and was independent of replication in peripheral blood mononuclear cells. Replication in MDMs provided a clear biological feature to distinguish among viruses that were otherwise identical by NSI phenotype, V3 genotype, and CCR5 coreceptor usage. Low-level MDM replication was characteristic of viruses isolated from asymptomatic individuals, including long-term survivors. Enhanced MDM replication was related to morbidity and mortality among patients. Replication levels in MDMs provide a novel prognostic indicator of pathogenic potential by NSI viruses.

Acquired Immunodeficiency Syndrome↗