NEW INSIGHTS INTO THE ANTIMICROBIAL ACTION FROM HTLV-1-INFECTED INDIVIDUALS TOWARD STAPHYLOCOCCUS AUREUS

Introduction: Human T-cell lymphotropic virus type 1 (HTLV-1) infection is endemic in Brazil and is linked with inflammatory conditions including HTLV-1-associated myelopathy (HAM). This chronic neuroinflammatory disease culminates in the loss of motor functions. HTLV-1 carriers exhibit a higher susceptibility to opportunistic infections, as caused by S. aureus (Sa) (Fron Med. (2024) 9:812016) 2022). Several proteins secreted by Sa may be related to its virulence, such as the serine protease SplD (PLoS One. (2024) 8:e76812) 2013). This work aimed to investigate the antimicrobial immunoglobulins and antibody-mediated responses from HTLV-1-infected patients. Methods and Results: Sera were obtained from asymptomatic carriers (AC), HAM, and uninfected individuals (NI)(CAAE: 46962821.1.0000.5262), and levels of IgG total, anti-Sa (ST30-strain), and IgG anti-SplD were evaluated by ELISA. HTLV-1-infected patients had higher total IgG levels than uninfected individuals. Results indicated that HAM patients presented higher titer of IgG anti-Sa than AC individuals. Moreover, HTLV-1-infected individuals, presented higher levels of IgG against SplD compared to NI donors. Following, we investigate the opsonophagocytosis capacity of monocytes using Sa stained with the SYTO9 probe, previously. Labeled bacteria were incubated with heat-inactivated serum, followed by an incubation with monocytes (THP-1 cell line) and then phagocytosis was evaluated by flow cytometry. Preliminary results showed that the opsonization promoted by serum from HTLV-1-infected patients induced lower phagocytosis than serum from NI individuals. Moreover, compared to other groups, the bacterial growth was higher after opsonization with serum from HAM patients and monocyte incubation. Conclusion: Although the results suggested that HTLV-1-infected individuals have high levels of IgG against Sa, the antibody-mediated responses were lower than NI, corroborating the susceptible infection state of these patients.