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.

Trypanosoma cruzi: requirements for induction and maintenance of protective immunity conferred by immunization.

Immunization with CL-14-trypomastigotes generates efficient humoral and cellular responses against infective challenge. Herein, we investigated the relevance of these mechanisms in vivo. Immunization with live CL-14-trypomastigotes protected only part of beta2m(-/-) mice but efficiently protected perforin-knockout mice. Fixed CL-14-trypomastigotes could successfully immunize BALB/c, though live trypomastigotes lowered the requirements for doses and time intervals. Post-immune depletion of CD4 or CD8 subsets did not affect protection conferred by immunization, but switched the production of anti-Trypanosoma cruzi antibodies to IgG2a. Sublethal irradiation partially broke the resistance of immune mice, leading to development of late parasitemia. Passive serum transfer from immune mice conferred protection to nai;ve mice. Our results indicate that presentation of cytosolic antigens by MHC class I molecules is involved in the generation of immunity and suggest that the humoral response contributes to a great extent to keep CL-14-immunized mice protected against infective challenge.