The hepatitis delta virus (HDV) is a globally distributed agent, and its genetic variability allows for it to be organized into eight genotypes with different geographic distributions. In South America, genotype 3 (HDV-3) is frequently isolated and responsible for the most severe form of infection. The objective of this study was to evaluate the evolutionary and epidemiological dynamics of HDV-3 over the years and to describe its distribution throughout this continent in an evolutionary perspective. While using Bayesian analysis, with strains being deposited in the Nucleotide database, the most recent common ancestor was dated back to 1964 and phylogenetic analysis indicated that the dispersion may have started in Brazil, spreading to Venezuela and then to Colombia, respectively. Exponential growth in the effective number of infections was observed between the 1950s and 1970s, years after the first report of the presence of HDV on the continent, during the Labrea Black Fever outbreak, which showed that the virus continued to spread, increasing the number of cases decades after the first reports. Subsequently, the analysis showed a decrease in the epidemiological levels of HDV, which was probably due to the implantation of the vaccine against its helper virus, hepatitis B virus, and serological screening methods implemented in the blood banks.

The emergence of clinically relevant mutations in the hepatitis B virus (HBV) genome has been a matter of great debate because of the possibility of escape from the host’s immune system, the potential to cause more severe progression of liver diseases and the emergence of treatment-resistant variants. Here we characterized the circulating variants of HBV in Rondônia State, in the north of Brazil. Serum samples of 62 chronic HBV carriers were subjected to PCR assays and clinical data were collected. Mutations and genotypes were characterized through direct sequencing. The findings show the presence of subgenotypes A1 (54.83%, 34/62), D3 (16.13%, 10/62), F2 (16.13%, 10/62), A2 (4.84%, 3/62), D2 (3.23%, 2/62), D1 (1.61%, 1/62), D4 (1.61%, 1/62) and F4 (1.61%, 1/62). Deletions in the pre-S2 region were found in 13.79% (8/58) of the samples, mutations in the S gene in 59.68% (37/62) and RT mutations in 48.39% (30/62). We found a variable genotypic distribution in different locations and important mutations related to immune escape and drug resistance in Western Amazonia, which contributed to genetic surveillance and provided important information to help control the disease.

The Brazilian Amazon region is a highly endemic area for hepatitis Delta and has areas that are difficult to access. Understanding the dynamics of HDV transmission in these remote locations is important for elucidating the routes of infection. To investigate this, a molecular analysis of HDV was conducted to assess the spatio-temporal dynamics of HDV cases. Between 2010 and 2023, 35 patients were recruited from the Viral Hepatitis Outpatient Clinic in Rondônia, Brazil. Conventional PCR was used to amplify the complete HDV genome followed by nucleotide sequencing via the Sanger method. The HDV genotype was determined using maximum likelihood phylogenetic reconstruction. A Skygrid coalescent approach with a Relaxed Random Walk phylogeographic model was used for the spatio-temporal analysis. Most individuals were males (21/35), with a median age of 39 years. HDV-3 was identified in all samples (35/35; 100%). The tMRCA was estimated to be 1824, with a substitution rate of 8.2 × 10⁻⁴ substitutions/site/year. The results suggest that HDV likely entered Brazil around 1820, in the state of Amazonas, subsequently spreading to Acre and Rondônia. Notable migration events were observed starting from 2010. This study suggests that HDV-3 has a complex evolutionary history spanning over two centuries, with intricate transmission routes in different locations in Brazil.

Hepatitis Delta represents a greater risk in the progression of advanced liver disease and HCC compared with HBV. The exact mechanism that determines the spontaneous clearance of delta virus or its progression to cirrhosis remains unknown. Therefore, this study aimed to analyze the clinical profile of HBV and HBV/HDV individuals in the Western Amazon. The study was carried out at the Specialized Outpatient Clinic for Viral Hepatitis belonging to the Centro de Pesquisa em Medicina Tropical de Rondônia/CEPEM. 100 individuals were included, stratified into two groups: 50 with hepatitis B virus and 50 with hepatitis Delta virus. The overall mean age was 48 years. For the HBV and HDV groups, 66 % (33/50) and 54 % (27/50) were men and 56 % (28/50) and 58 % (29/50) were on antiviral treatment, respectively. Patients with detectable HDV-RNA demonstrated high levels of ALT and AST compared to individuals with undetectable HDV-RNA. Comparative analysis between HBV carriers and infected with HDV shows significant differences in terms of age, HBV-DNA levels, albumin, hepatomegaly and splenomegaly. Several markers were important for differentiating HBV and HDV infections. HDV-RNA detectable showed significant changes in biomarkers compared to undetectable patients, suggesting a possible worse prognostic effect in this group.

Genomic surveillance represents an important strategy for understanding evolutionary mechanisms, transmission profile, and infectivity of different SARS-CoV-2 variants. We assessed the epidemiological profile of 366 individuals who tested positive for SARS-CoV-2 from 29 municipalities in Rondônia between December 2021 to March 2022. Samples were collected, RNA was ex-tracted and screened using RT-qPCR for Alpha, Beta, Gamma, Delta and Omicron VOCs and viral quantification was performed. Sequences were analyzed for phylogeny, mutations and lineages. Of the samples analyzed, 93.71% were positive for the Omicron variant and 6.28% were positive for the Delta variant. The symptoms observed were cough, sore throat, and fever, with a mean duration of 5 days; no hospitalizations or deaths were reported. We noted that among the positive individuals, 51% had been immunized with two doses, 22% received three doses, 13% received one dose, and 13% were not immunized. Just 242 samples were amenable to analysis for alignment and phylogenetic characterization; corresponding to variants BA.1 and BA.1.1; a total of 120 mutations were identified, 36% of which were found in the S gene. In conclusion, there was a high frequency of mutations in the SARS-CoV-2 genome, but no record of clinical severity, demonstrating the positive effect of vaccination.

In Brazil, the Amazon region has the highest rate of infection by the hepatitis Delta virus, and owing to regional difficulties in transporting and storing samples, especially in remote regions and isolated populations, the expansion of molecular diagnosis has become a significant public health problem. This study aims to analyze the stability of HDV under different temperature and storage conditions, providing essential information for the expansion of the molecular diagnosis of Hepatitis Delta. Whole blood, serum, and plasma samples were collected from chronic HDV patients. The samples were subjected to different temperatures and storage conditions, and HDV-RNA detection was performed via RT-qPCR. HDV was stable under various temperature conditions, including high temperatures, with minimal variations in Ct values. Compared with cryopreserved samples, DBS samples presented greater variation. The results suggest that HDV can remain detectable for up to 96 h when stored at room temperature, 4 °C, -30 °C, and − 80 °C and for up to 72 h at temperatures ranging from 4 °C to 42 °C, in addition to the possibility of detection via filter paper, although with reduced sensitivity. HDV is stable under different conditions, which is crucial for molecular diagnostics in regions with adverse storage conditions.