Co-infections of Orthopoxviruses (OPVs), such as vaccinia virus (VACV) and monkeypox virus (MPXV), and the human immunodeficiency virus (HIV) can be associated with severe outcomes. Serro’s dairy region, located in Minas Gerais, southeastern Brazil, is an endemic area for VACV, where zoonotic outbreaks affect rural communities. This epidemiological context is especially relevant for at-risk populations, such as people living with HIV (PLHIV). This study aimed to assess the presence of neutralizing antibodies (NAbs) against OPV in PLHIV in this endemic setting. Serum samples were collected from 177 PLHIV in treatment at the specialized service between December 2021 and August 2022. VACV and MPXV NAbs were measured using the plaque reduction neutralization test (PRNT) and VACV-infected cells. The overall occurrence of OPV NAbs was 27.7%. NAbs were higher in individuals born before 1980 (53.3%) than those born after 1980 (1.1%). Among anti-VACV-seropositive individuals, 40.8% also had MPXV NAbs, suggesting cross-immunity. These findings indicate the circulation of VACV in PLHIV and highlight the increased susceptibility to OPV infections among individuals born after the cessation of smallpox vaccination. The results reinforce the importance of continued surveillance of OPV, especially in endemic regions and vulnerable populations.

Despite current literature pointing to a link between shortened telomeres and aging, chronic diseases, and geriatric syndromes, the precise implications of this connection remain unclear. The aim of this exploratory, cross-sectional, observational study was to investigate the association between the relative telomere length (RTL) of peripheral blood leukocyte subtypes (mononuclear cells and granulocytes) and physical performance using the Short Physical Performance Battery (SPPB) in older adults. A cohort of 95 participants was recruited, which included men and women aged over 60 years (70.48 ± 5.5 years). It was found that mononuclear cell RTL was significantly lower than that of granulocytes ( p < 0.0001). Moreover, individuals with good SPPB performance exhibited lower mononuclear cell RTL compared with those with moderate or poor performance. However, no significant differences were observed in granulocyte RTL between different SPPB performance groups. The global SPPB score showed an inverse correlation with mononuclear cell RTL, but this correlation was not present with granulocyte RTL. Similarly, the SPPB sit-to-stand domain correlated with mononuclear cell RTL, but no such correlation was found with granulocyte RTL. Our findings challenge conventional expectations, suggesting that shorter mononuclear cell RTL may be associated with favorable functional capacity. The variations in RTL between mononuclear cells and granulocytes highlight their distinct biological roles and turnover rates. A history of immune responses may influence mononuclear cell RTL dynamics, while telomerase activity may protect granulocyte RTL from significant shortening. The unexpected associations observed in mononuclear cell RTL emphasize the complex interplay between immune responses, cellular aging, and functional capacity in older adults.