Coronavirus disease (COVID-19), caused by the virus SARS-CoV-2, is already responsible for more than 4.3 million confirmed cases and 295,000 deaths worldwide as of May 15, 2020. Ongoing efforts to control the pandemic include the development of peptide-based vaccines and diagnostic tests. In these approaches, HLA allelic diversity plays a crucial role. Despite its importance, current knowledge of HLA allele frequencies in South America is very limited. In this study, we have performed a literature review of datasets reporting HLA frequencies of South American populations, available in scientific literature and/or in the Allele Frequency Net Database. This allowed us to enrich the current scenario with more than 12.8 million data points. As a result, we are presenting updated HLA allelic frequencies based on country, including 91 alleles that were previously thought to have frequencies either under 5% or of an unknown value. Using alleles with an updated frequency of at least ≥5% in any South American country, we predicted epitopes in SARS-CoV-2 proteins using NetMHCpan (I and II) and MHC flurry. Then, the best predicted epitopes (class-I and -II) were selected based on their binding to South American alleles (Coverage Score). Class II predicted epitopes were also filtered based on their three-dimensional exposure. We obtained 14 class-I and four class-II candidate epitopes with experimental evidence (reported in the Immune Epitope Database and Analysis Resource), having good coverage scores for South America. Additionally, we are presenting 13 HLA-I and 30 HLA-II novel candidate epitopes without experimental evidence, including 16 class-II candidates in highly exposed conserved areas of the NTD and RBD regions of the Spike protein. These novel candidates have even better coverage scores for South America than those with experimental evidence. Finally, we show that recent similar studies presenting candidate epitopes also predicted some of our candidates but discarded them in the selection process, resulting in candidates with suboptimal coverage for South America. In conclusion, the candidate epitopes presented provide valuable information for the development of epitope-based strategies against SARS-CoV-2, such as peptide vaccines and diagnostic tests. Additionally, the updated HLA allelic frequencies provide a better representation of South America and may impact different immunogenetic studies.

The COVID-19 pandemic has caused widespread infections, deaths, and substantial economic losses. Vaccine development efforts have led to authorized candidates reducing hospitalizations and mortality, although variant emergence remains a concern. Peru faced a significant impact due to healthcare deficiencies. This study employed logistic regression to mathematically model COVID-19’s dynamics in Peru over three years and assessed the correlations between cases, deaths, and people vaccinated. We estimated the critical time (t_c) for cases (627 days), deaths (389 days), and people vaccinated (268 days), which led to the maximum speed values on those days. Negative correlations were identified between people vaccinated and cases (−0.40) and between people vaccinated and deaths (−0.75), suggesting reciprocal relationships between those pairs of variables. In addition, Granger causality tests determined that the vaccinated population dynamics can be used to forecast the behavior of deaths (p-value < 0.05), evidencing the impact of vaccinations against COVID-19. Also, the coefficient of determination (R²) indicated a robust representation of the real data. Using the Peruvian context as an example case, the logistic model’s projections of cases, deaths, and vaccinations provide crucial insights into the pandemic, guiding public health tactics and reaffirming the essential role of vaccinations and resource distribution for an effective fight against COVID-19.

Hepatitis B virus (HBV) infection remains a global public health concern, with perinatal transmission as the primary route in endemic populations. Ayacucho is a priority region due to its high incidence (second nationally between 2019 and 2024) and the significant decline in vaccination coverage (~15%). This study aims to synthesize existing epidemiological evidence on HBV seroprevalence in Ayacucho, Peru, emphasizing temporal changes observed before and after the implementation of vaccination programs to inform control strategies. This review was conducted, integrating data from diverse population groups, including children, pregnant women, blood donors, high-risk individuals (military personnel, female sex workers, prisoners), and household contacts, to identify transmission patterns and evaluate the impact of immunization efforts. Historically, Ayacucho was hyperendemic, with an HBsAg prevalence of 20% in Huanta (1985–1986) and a high mortality from liver diseases. The introduction of a vaccination in the 1990s led to a drastic reduction in infection rates among children, from 24.4–30.4% (1994) to 2.3–5.1% (1997), and improved overall Expanded Program on Immunization (EPI) coverage. However, recent data (2000–2024) reveal a concerning increase in HBV cases since 2012, with peaks in 2016 and 2023, correlating with a decline in vaccination rates post-2021. HBV prevalence remains elevated among high-risk populations—including military personnel, female sex workers, and prisoners—as well as among blood donors (HBsAg: 3.73–5.0%; anti-HBc: 21–33%). In addition, significant knowledge gaps and low adherence to EPI strategies were observed. Despite initial vaccination success, Ayacucho faces a resurgence of HBV infection, exacerbated by declining vaccine coverage and vulnerabilities in high-risk populations. Reinforcing immunization programs and screening strategies is urgent to control and eventually eliminate HBV cases in the region.

The monkeypox virus (MPXV) has caused an unusual epidemiological scenario—an epidemic within a pandemic (COVID-19). Despite the inherent evolutionary and adaptive capacity of poxviruses, one of the potential triggers for the emergence of this epidemic was the change in the status of orthopoxvirus vaccination and eradication programs. This epidemic outbreak of HMPX spread worldwide, with a notable frequency in Europe, North America, and South America. Due to these particularities, the objective of the present study was to assess and compare cases of HMPX in these geographical regions through logistic and Gompertz mathematical modeling over one year since its inception. We estimated the highest contagion rates (people per day) of 690, 230, 278, and 206 for the world, Europe, North America, and South America, respectively, in the logistic model. The equivalent values for the Gompertz model were 696, 268, 308, and 202 for the highest contagion rates. The Kruskal–Wallis Test indicated different means among the geographical regions affected by HMPX regarding case velocity, and the Wilcoxon pairwise test indicated the absence of significant differences between the case velocity means between Europe and South America. The coefficient of determination (R²) values in the logistic model varied from 0.8720 to 0.9023, and in the Gompertz model, they ranged from 0.9881 to 0.9988, indicating a better fit to the actual data when using the Gompertz model. The estimated basic reproduction numbers (${\mathcal{R}}_0$) were more consistent in the logistic model, varying from 1.71 to 1.94 in the graphical method and from 1.75 to 1.95 in the analytical method. The comparative assessment of these mathematical modeling approaches permitted the establishment of the Gompertz model as the better-fitting model for the data and the logistic model for the ${\mathcal{R}}_0$. However, both models successfully represented the actual HMPX case data. The present study estimated relevant epidemiological data to understand better the geographic similarities and differences in the dynamics of HMPX.

Nitrogen-fixing cyanobacterial consortia are an alternative to the indiscriminate use of chemical fertilizers that affect the environment, fix atmospheric nitrogen, and can therefore be used as plant growth promoters, synthesize various substances such as auxins, vitamins, and total proteins, and fix atmospheric biofertilizers and soil conditioners. The present study aimed to obtain and develop, by biotechnological means, two consortia of cyanobacteria isolated from the root and rhizosphere of Carica papaya grown in sandy loam soil. The culture was carried out in Blue Green Medium without modified nitrogen (BG11₀), with aeration of 0.32 L min⁻¹, at a light intensity of 48.83 μEm⁻²s⁻¹, and a temperature of 22 ± 2 °C. Two consortia consisting of Nostoc commune, Aphanothece minutissima, Planktothrix sp. (C1), Nostoc commune, Calothrix sp., and Aphanothece minutissima (C2) were isolated and morphologically identified. The effective development of these consortia was verified at the laboratory level by obtaining biomass in dry weight as well as photosynthetic pigments, proteins, carbohydrates, and lipids. Germination parameters were determined in seeds of Cucumis sativus L. var. Market plus treated with the nitrogen-fixing cyanobacteria consortia, obtaining a higher germination percentage (>90%), greater root length (>6 cm), and higher vigour index I (513), II (13.02) for the C2 consortium. This broadens the spectrum of rhizosphere-derived microorganisms with potential as growth biostimulators.

Hepatitis B virus (HBV) genotype F is one of the most genetically divergent and evolutionarily ancient HBV lineages and predominantly circulates in indigenous and admixed populations of the Americas. Here, we performed a comprehensive evolutionary and inferred functional characterization of the HBV genotype F via the largest curated dataset of complete genomes. Phylogenomic reconstruction, recombination screening, and phylogenetic network analyses were integrated with codon-based selective pressure inference, surface protein posttranslational modification profiling, mutational analysis of antigenic regions, and reverse transcriptase (RT) drug resistance assessment. The HBV-F subgenotype exhibited a well-resolved phylogenetic structure and limited intragenotypic recombination, while intergenotypic recombination contributed substantially to reticulate evolutionary signals. Selective pressure analyses revealed strong purifying selection in replication-associated domains of the polymerase, in contrast to episodic adaptive evolution in surface-exposed and regulatory proteins, particularly the X protein. N-glycosylation sites in large surface proteins are highly conserved. Some mutations in the major hydrophilic region (MHR) were significantly detected, whereas RT drug resistance mutations were rare and followed canonical lamivudine-associated pathways. Collectively, these findings highlight the balance between deep evolutionary conservation and localized adaptive flexibility in shaping the HBV genotype F and provide a genotype-specific framework for interpreting viral fitness, immune interactions, and antiviral resistance.