Investigation of the effects of CD4+ T lymphocyte count on the humoral response to SARS-CoV-2 in people living with HIV in advanced age

• Grant number: 24/08460-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2024
• End date: July 31, 2025
• Field of knowledge: Biological Sciences - Immunology - Applied Immunology
• Principal Investigator: Cássia Gisele Terrassani Silveira
• Grantee: Marcos Vinícius Lemes Toquetão
• Host Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Adherence to antiretroviral therapy among people living with HIV in Brazil has significantly increased the life expectancy of this group in recent decades. Concurrently, the recent COVID-19 pandemic has highlighted the importance of providing assistance to groups more susceptible to severe outcomes in cases of infections, such as elderly individuals or those with low CD4+ T-cell counts. The humoral response triggered by vaccination or natural infection acts as a protective barrier against reinfections and viral load control, reducing the progression to severe outcomes. A robust and efficient humoral response depends on the quantity and physiological condition of cells involved in B-cell stimulation mechanisms for the production of high-affinity neutralizing antibodies. Fundamentally, T lymphocytes are essential in the activation process of B lymphocytes and in the production of antibodies with higher affinity, especially the follicular T-helper cell subset (Tfh). Elderly individuals living with HIV tend to exhibit weakened immune responses, T-cell exhaustion, and low CD4+ T-cell counts. The combination of these conditions in these individuals can compromise an effective humoral response and, consequently, increase the chance of severe outcomes from infections. Therefore, it is of interest to public health authorities and the scientific community to elucidate the humoral response profile of these individuals in order to promote immunization policies and comprehensive care for these groups. This project, in partnership with the international multicenter consortium Longitudinal Study of HIV and Aging in Brazil (ELEA-Brazil), aims to investigate the neutralization capacity against SARS-CoV-2 variants in individuals living with HIV above 50 years old based on CD4+ T lymphocyte count.