Glycosylation of host and viral proteins is an important posttranslational modification needed to ensure correct function of glycoproteins. For this reason, we asked whether inhibition of O-glycosylation during human immunodeficiency virus (HIV) in vitro replication could affect HIV infectivity and replication rates. We used benzyl-2-acetamido-2-deoxy-α-d-galactopyranoside (BAGN), a compound that has been widely used to inhibit O-glycosylation in several cell lines. Pretreatment and culture of PHA-blast target cells with BAGN increased the percentage of HIV-infected cells (7.6-fold, p = 0.0115), the per-cell amount of HIV p24 protein (1.3-fold, p = 0.2475), and the viral particles in culture supernatants (7.1-fold, p = 0.0029) compared to BAGN-free cultures. Initiating infection with virus previously grown in the presence of BAGN further increased percentage of infected cells (30-fold, p < 0.0001), intracellular p24 (1.5-fold, p = 0.0433), and secreted viral particles (74-fold, p < 0.0001). BAGN-treated target cells showed less CD25 and CCR5 expression, but increased HLA-DR surface expression, which positively correlated with the number of infected cells. Importantly, BAGN improved viral outgrowth kinetics in 66% of the samples tested, including samples from HIV controllers and subjects in whom no virus could be expanded in the absence of BAGN. Sequencing of the isolated virus indicated no skewing of viral quasi-species populations when compared to BAGN-free culture conditions. BAGN also increased virus production in the ACH2 latency model when used together with latency-reversing agents. Taken together, our results identify BAGN treatment as a simple strategy to improve viral outgrowth in vitro and may provide novel insights into host restriction mechanisms and O-glycosylation-related therapeutic targets for HIV control strategies.

The present study was supported by grant PI12/00529 (AO) from the Instituto de Salud Carlos III, co-financed by the Fondo Europeo de Desarrollo Regional (FEDER) “Una manera de hacer Europa” and funding from the European Union's Horizon 2020 research and innovation program under grant European AIDS Vaccine Initiative 2020 (EAVI2020) #GA681137 (CB). JM and AM were supported by a grant from the Spanish Ministry of Economy, Industry and Competitiveness and FEDER grant no. SAF2016-75505-R (AEI/MINEICO/FEDER, UE). CB and AM are senior ICREA research professors. The HIVACAT program, Foundation Dormeur, Vaduz (Liechtenstein), and an unrestricted gift by Rafael Punter, Barcelona (Spain) and the Gala SIDA 2014-2016, further supported the work.