Rosa Elena Sarmiento-Silva

Emerging infectious diseases represent a major global health challenge, with a significant proportion that are zoonoses (Jones et al. 2008; Tazerji et al. 2022; García-Moreno 2023), i.e. pathogens ...

PPV5 NS1 is a nonstructural and multifunctional protein comprising helicase and nuclease domains. The helicase domain contains conserved motifs from superfamily 3 helicases, including Walker A, Walker B, Motif B’, Motif C, and Box VII, whereas the nuclease domain consists of glutamate, a HUH motif, lysine, and tyrosine. In Mexico, the reported prevalence of PPV5 is higher than in other countries, with notable amino acid differences compared with pathogenic PPVs. This study compares the helicase and nuclease domains from a full-length PPV5 NS1 sequence with porcine parvovirus 1 (PPV1) and canine parvovirus (CPV) to characterize the protein further and perform three-dimensional (3D) modeling using bioinformatic tools, including solvent-accessible surface area (SASA) and electrostatic potential assessments. The main findings highlight the ATP-binding pocket, showing electrostatic values in PPV5 that contrast with PPV1 and CPV. The electrostatic potential 3D models suggest those differences involve non-conserved regions. In particular, the PPV5 Box VII surface is predominantly negative due to a glutamate substitution at position 7. In the nuclease domain, the interaction with Mg²⁺ differs between PPV5 and pathogenic PPV. The electrostatic findings suggest that these differences may have functional implications for both domains, but confirmation must be completed with functional assays.

Zoonotic diseases involve pathogen transmission between humans and animals, with most research focused on animal-to-human spillover. However, reverse zoonosis—the transmission of pathogens from humans to animals—remains understudied despite its potential ecological and epidemiological consequences. The SARS-CoV-2 pandemic highlights this risk, as human-associated viruses may sporadically infect wildlife species and generate novel exposure pathways. To assess evidence of SARS-CoV-2 exposure in wildlife, we analyzed serum and rectal swab samples from rodents collected in rural localities of the Yucatan Peninsula, Mexico, between 2021 and 2022. An indirect ELISA detected antibodies against SARS-CoV-2 in 23.1% of sampled rodents. Molecular analysis detected one positive sample with a pan-coronavirus RT-PCR, though all were negative for SARS-CoV-2–specific assays. This study provides serological evidence of SARS-CoV-2 exposure in rodent communities from rural areas of Mexico and is consistent with sporadic wildlife spillback events rather than sustained transmission. The observed exposure patterns may be influenced by human activities and frequent human–wildlife interactions in heterogeneous rural landscapes. Our results underscore the need for integrated serological and genomic surveillance to better understand the ecological context of reverse zoonosis and its implications for public health.

The porcine epidemic diarrhea virus (PEDV) causes a gastrointestinal disease generating mortality rates approaching 100% in piglets worldwide. The S glycoprotein of PEDV is the main target for the development of vaccines. Two vaccines approved by the Ministry of Agriculture and Rural Development are used in Mexico: the first vaccine is based on an inactivated virus isolated more than a decade ago, whereas the second vaccine is based on mRNA technology. The most important tool for controlling PEDV outbreaks is vaccination; however, coronaviruses are characterized by the accumulation of multiple mutations, which compromise the immune response elicited by outdated vaccines. In this work, we classified the Mexican strains of PEDV reported so far in GenBank, according to their genotypes. Subsequently, we searched for B and T cell epitopes conserved in Mexican PEDV strains using bioinformatic tools. In addition, we explored whether these epitopes can induce allergies, autoimmunity, and/or toxic effects. Next, we determined the localization of B cell epitopes in the S glycoprotein using the protein crystal and protein modeling of several S glycoproteins. Finally, we carried out molecular docking analysis to assess whether these T cell epitopes could interact with the peptide-binding groove of the Swine Leukocyte Antigens (SLAs). Five conserved B cell epitopes were found to be exposed on the surface of the S glycoprotein, whereas several promiscuous CTL and HTL epitopes were bound, with low free energy, to the peptide-binding grooves of SLA-I and SLA-II, respectively. The best epitopes were used to generate a plasmid carrying the sequence to produce a recombinant protein. This plasmid was used for transfection experiments in PK-15 cell culture. The B cell epitopes reported here were recognized by the sera from pigs infected with PEDV but not by the sera from uninfected animals. These results justify future evaluations of the ability of these epitopes to stimulate cytokine production by T cells, antibody generation, and their neutralizing activity.

Coronavirus (CoV) spillover from wildlife to humans is increasing and has caused major global epidemics, facilitated by human-induced habitat alteration that promotes zoonotic emergence. This highlights the need for sustained surveillance and a better understanding of circulation patterns within wildlife reservoirs. Although Neotropical bats harbour a highly diverse CoV community, how host traits and ecological factors shape CoV circulation and virus–host associations remains poorly characterized. During 2021–3, we conducted extensive bat sampling across 12 localities along an anthropogenic land-use gradient in the Yucatan Peninsula, Mexico, to characterize bat community diversity. We then screened bats for CoVs and evaluated the association between CoV detection and host traits and ecological variables. Detected CoVs were subsequently sequenced and phylogenetically characterized. Using publicly available databases and host phylogenetic diversity metrics, we further analysed the putative host range of each identified CoV taxon and their distribution along the gradient. Bat diversity was significantly lower in urban sites. Although overall CoV positivity was low (3.2%), we identified eight divergent CoV taxa, including two novel Alphacoronavirus sequences, one of which represents the first CoV reported from Lophostoma brasiliense. Juvenile bats were more likely to be CoV-positive, a pattern particularly pronounced in Sturnira parvidens but absent in Artibeus jamaicensis. We found variation in putative host breadth among the identified CoV taxa, supported by differences in host phylogenetic distances. Notably, CoV taxa detected at sites with lower bat diversity were associated with a greater number of reported host species and higher host phylogenetic diversity. Our findings expand the known diversity of Neotropical bat CoVs and reveal distinct patterns in CoV detection and virus–host associations across viral taxa. Sustained viral surveillance, complemented by broader genomic studies and deeper investigation into variation within and among CoV taxa, is needed to clarify these patterns, guide research priorities in the Neotropical CoVs, and help mitigate the risk of future zoonotic emergence.

The activity of respiratory viruses (RVs) displays large variability in tropical regions, posing challenges for public health response strategies. Data from most RVs in south-eastern Mexico remain limited, particularly in the Yucatan Peninsula, the largest tourism hub in the country. This retrospective study analyses the regional epidemiology of RVs in Merida, the largest city in the region, using laboratory test data from a local hospital (January 2018–April 2024). Test results of 143292 RVs were collected, including 121976 for SARS-CoV-2, 19355 for influenza A and B viruses, and 1961 for 17 distinct RVs. We found that non-SARS-CoV-2 RVs circulated year-round, with higher activity in autumn and spring, while SARS-CoV-2 peaked in summer and winter. Influenza A virus, respiratory syncytial virus, and influenza B virus reached their highest activity in autumn, earlier than in other regions of Mexico. Human metapneumovirus peaked during autumn-winter. Rhinovirus/enterovirus and parainfluenza showed year-round activity, with peaks in autumn and spring. Other coronaviruses were more frequent during winter-spring. In post-pandemic years (2022–2023), adenovirus outbreaks emerged, as well as an increased prevalence of non-SARS-CoV-2 RV co-infections. This study highlights the need for region-specific public health strategies, including optimized vaccination schedules, such as for influenza A virus, and enhanced diagnostic surveillance.

A one-pot synthetic methodology that combines an Ugi-Zhu three-component reaction (UZ-3CR) with a cascade sequence (intermolecular aza Diels–Alder cycloaddition/intramolecular N-acylation/decarboxylation/dehydration) using microwave-heating conditions, ytterbium (III) triflate (Yb(OTf)₃) as the catalyst, and chlorobenzene (for the first time in a multi-component reaction (MCR)) as the solvent, was developed to synthesize twelve new fluorinated-pyrrolo[3,4-b]pyridin-5-ones containing a 4-amino-7-chloroquinoline moiety, yielding 50–77% in 95 min per product, with associated atom economies around 88%, also per product. Additionally, by in vitro tests, compounds 19d and 19i were found to effectively stop early SARS-CoV-2 replication, IC₅₀ = 6.74 µM and 5.29 µM, at 0 h and 1 h respectively, while cell viability remained above 90% relative to the control vehicle at 10 µM. Additional computer-based studies revealed that the most active compounds formed strong favorable interactions with important viral proteins (M_pro, NTDα and NTDo) of coronavirus, supporting a two-pronged approach that affects both how the virus infects the cells and how it replicates its genetic material. Finally, quantum chemistry analyses of non-covalent interactions were performed from Density-Functional Theory (DFT) to better understand how the active compounds hit the virus.

Human activities and land use changes have a major impact on the distribution and diversity of mosquito vectors and their associated viruses. This study describes the diversity and differential abundance of viruses associated with mosquito species from four habitats of the Yucatan Peninsula, Mexico. Using next-generation sequencing (NGS), we analyzed 61 genomic libraries belonging to 20 mosquito species to characterize the viral community. A total of 16 viral species were identified, representing 14 different viral families. Most identified viruses were associated with insects, plants, and fungi. Additionally, vertebrate associated viral families, including Herpesviridae, Peribunyaviridae, Nairoviridae, and Arenaviridae, were detected in mosquitoes from urban habitats. Notably, insect-associated viruses like Hubei mosquito virus 4 and Hubei virga-like virus 2 were identified, along with the first report of Mercadeo virus in Mexico. Variations in viral community composition were primarily driven by mosquito species, with species of the same genus maintaining similar viromes despite occupying different habitats. These findings reinforce that intrinsic traits of mosquito species play a key role in shaping viral community composition. To our knowledge, this is the first study that describes the viral community in mosquitoes in Yucatan Peninsula, Mexico. This study provides essential baseline data for the surveillance of mosquitoes and associated viruses from a biodiverse tropical region that faces strong land use modifications.

Porcine circovirus type 2 (PCV2) is a pervasive pathogen in the swine industry, leading to a spectrum of disorders known as porcine circovirus associated diseases (PCVAD). The PCV2 Cap protein contains critical antigenic epitopes and is the primary target for vaccine development. Current vaccines include inactivated viral particles and virus-like particles (VLPs), with experimental vaccines exploring various innovative approaches. This study introduces a novel Golden Gate assembly-based, Escherichia coli expression destination plasmid, pPRSVCP-E18, designed for the in-frame insertion of short peptide-coding DNA sequences into a highly antigenic site of Papaya ringspot virus (PRSV) coat protein (CP). We successfully cloned four PCV2 Cap peptides into this plasmid, expressed the chimeric CP proteins in E. coli under flask and bioreactor conditions, and assembled them into VLPs. These VLPs, when adjuvated and administered to BALB/c mice, elicited a specific IgG response against the PCV2 Cap peptides. Our findings demonstrate the plasmid’s high efficiency for Golden Gate cloning and its potential in developing subunit vaccines against PCV2, contributing to the sustainable control of PCVAD in the swine industry.