Evolution during primary HIV infection does not require adaptive immune selection

Modelling HIV-1 control and remission

Remarkable advances are being made in developing interventions for eliciting long-term remission of HIV-1 infection. The success of these interventions will obviate the need for lifelong antiretroviral therapy, the current standard-of-care, and benefit the millions living today with HIV-1. Mathematical modelling has made significant contributions to these efforts. It has helped elucidate the possible mechanistic origins of natural and post-treatment control, deduced potential pathways of the loss of such control, quantified the effects of interventions, and developed frameworks for their rational optimization. Yet, several important questions remain, posing challenges to the translation of these promising interventions. Here, we survey the recent advances in the mathematical modelling of HIV-1 control and remission, highlight their contributions, and discuss potential avenues for future developments.

Mild HIV-specific selective forces overlaying natural CD4+ T cell dynamics explain the clonality and decay dynamics of HIV reservoir cells

The latent reservoir of HIV persists for decades in people living with HIV (PWH) on antiretroviral therapy (ART). To determine if persistence arises from the natural dynamics of memory CD4+ T cells harboring HIV, we compared the clonal dynamics of HIV proviruses to that of memory CD4+ T cell receptors (TCRβ) from the same PWH and from HIV-seronegative people. We show that clonal dominance of HIV proviruses and antigen-specific CD4+ T cells are similar but that the field's understanding of the persistence of the less clonally dominant reservoir is significantly limited by undersampling. We demonstrate that increasing reservoir clonality over time and differential decay of intact and defective proviruses cannot be explained by mCD4+ T cell kinetics alone. Finally, we develop a stochastic model of TCRβ and proviruses that recapitulates experimental observations and suggests that HIV-specific negative selection mediates approximately 6% of intact and 2% of defective proviral clearance. Thus, HIV persistence is mostly, but not entirely, driven by natural mCD4+ T cell kinetics.

Immune Mechanisms Underlying Hepatitis B Surface Antigen Seroclearance in Chronic Hepatitis B Patients With Viral Coinfection

It is considered that chronic hepatitis B patients have obtained functional cure if they get hepatitis B surface antigen (HBsAg) seroclearance after treatment. Serum HBsAg is produced by cccDNA that is extremely difficult to clear and dslDNA that is integrated with host chromosome. High HBsAg serum level leads to failure of host immune system, which makes it unable to produce effective antiviral response required for HBsAg seroclerance. Therefore, it is very difficult to achieve functional cure, and fewer than 1% of chronic hepatitis B patients are cured with antiviral treatment annually. Some chronic hepatitis B patients are coinfected with other chronic viral infections, such as HIV, HCV and HDV, which makes more difficult to cure. However, it is found that the probability of obtaining HBsAg seroclearance in patients with coinfection is higher than that in patients with HBV monoinfection, especially in patients with HBV/HIV coinfection who have an up to 36% of HBsAg 5-year-seroclerance rate. The mechanism of this interesting phenomenon is related to the functional reconstruction of immune system after antiretroviral therapy (ART). The quantity increase and function recovery of HBV specific T cells and B cells, and the higher level of cytokines and chemokines such as IP-10, GM-CSF, promote HBsAg seroclearance. This review summarizes recent studies on the immune factors that have influence on HBsAg seroconversion in the chronic hepatitis B patients with viral coinfection, which might provide new insights for the development of therapeutic approaches to partially restore the specific immune response to HBV and other viruses.