Mpox outbreak in Rio de Janeiro, Brazil: A translational approach.

Mpox is a zoonotic disease historically reported in Africa. Since 2003, limited outbreaks have occurred outside Africa. In 2022, the global spread of cases with sustained interhuman transmission and unusual disease features raised public health concerns. We explore the mpox outbreak in Rio de Janeiro (RJ) state, Brazil, in an observational study of mpox-suspected cases from June to December 2022. Data collection relied on a public healthcare notification form. Diagnosis was determined by MPXV-PCR. In 46 confirmed cases, anti-OPXV IgG was determined by ELISA, and seven MPXV genomes were sequenced. A total of 3095 cases were included, 816 (26.3%) with positive MPXV-PCR results. Most positive cases were men in their 30 s and MSM. A total of 285 (34.9%) MPXV-PCR+ patients live with HIV. Eight were coinfected with varicella-zoster virus. Anogenital lesions and adenomegaly were associated with the diagnosis of mpox. Females and individuals under 18 represented 9.4% and 5.4% of all confirmed cases, respectively, showing higher PCR cycle threshold (Ct) values and fewer anogenital lesions compared to adult men. Anti-OPXV IgG was detected in 29/46 (63.0%) patients. All analyzed sequences belonged to clade IIb. In RJ state, mpox presented a diverse clinical picture, represented mainly by mild cases with low complication rates and prominent genital involvement. The incidence in females and children was higher than usually reported. The observation of a bimodal distribution of Ct values, with few positive results, may suggest the need to review the diagnostic criteria in these groups.

Oligosymptomatic long-term carriers of SARS-CoV-2 display impaired innate resistance but increased high-affinity anti-spike antibodies.

The vast spectrum of clinical features of COVID-19 keeps challenging scientists and clinicians. Low resistance to infection might result in long-term viral persistence, but the underlying mechanisms remain unclear. Here, we studied the immune response of immunocompetent COVID-19 patients with prolonged SARS-CoV-2 infection by immunophenotyping, cytokine and serological analysis. Despite viral loads and symptoms comparable to regular mildly symptomatic patients, long-term carriers displayed weaker systemic IFN-I responses and fewer circulating pDCs and NK cells at disease onset. Type 1 cytokines remained low, while type-3 cytokines were in turn enhanced. Of interest, we observed no defects in antigen-specific cytotoxic T cell responses, and circulating antibodies displayed higher affinity against different variants of SARS-CoV-2 Spike protein in these patients. The identification of distinct immune responses in long-term carriers adds up to our understanding of essential host protective mechanisms to ensure tissue damage control despite prolonged viral infection.

Plasma and memory antibody responses to Gamma SARS-CoV-2 provide limited cross-protection to other variants.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to be a global problem in part because of the emergence of variants of concern that evade neutralization by antibodies elicited by prior infection or vaccination. Here we report on human neutralizing antibody and memory responses to the Gamma variant in a cohort of hospitalized individuals. Plasma from infected individuals potently neutralized viruses pseudotyped with Gamma SARS-CoV-2 spike protein, but neutralizing activity against Wuhan-Hu-1-1, Beta, Delta, or Omicron was significantly lower. Monoclonal antibodies from memory B cells also neutralized Gamma and Beta pseudoviruses more effectively than Wuhan-Hu-1. 69% and 34% of Gamma-neutralizing antibodies failed to neutralize Delta or Wuhan-Hu-1. Although Class 1 and 2 antibodies dominate the response to Wuhan-Hu-1 or Beta, 54% of antibodies elicited by Gamma infection recognized Class 3 epitopes. The results have implications for variant-specific vaccines and infections, suggesting that exposure to variants generally provides more limited protection to other variants.