Identification of SARS-CoV-2 in urban rodents from Southern Mexico City at the beginning of the COVID-19 pandemic

ABSTRACT Currently, there are some concerns about the situation and, in particular, about the future of the COVID-19 pandemic and the new emerging variants of SARS-CoV-2. Rodents are an example of synanthropic animals in urban environments that harbor important zoonoses. Although the molecular identification of SARS-CoV-2 in Rattus norvegicus from New York City had been reported, in other studies, urban wild rodents infected with this virus have not been found. This study aimed to molecularly identify the presence of SARS-CoV-2 in urban wild rodents from Mexico City, trapped along a water channel of a public park as part of a pest control program, at the beginning of the COVID-19 pandemic, during the fall and winter of 2020. Up to 33 Mus musculus and 52 R. norvegicus were captured and euthanized, large intestine samples with feces from the animals were obtained. RNAs were obtained and subjected to qRT-PCR for SARS-CoV-2 identification and threshold cycle (Ct) values were obtained. Four mice (12.1%) and three rats (5.8%) were positive, three rodents exhibited Ct<30. Our results on the frequency of SARS-CoV-2 in urban rats are in line with other previous reports. Thus, similar to other authors, we suggest that surveillance for the detection of SARS-CoV-2 in urban wild rodents, as sentinel animals, should be maintained.

Trypanosoma cruzi DTU II coinfection with bacteria producing prolonged cutaneous lesion in a healthy young male

ABSTRACT Chagas disease (CD) is a neglected tropical disease caused by Trypanosoma cruzi and is genetically classified in six discrete typing units (DTUs). The isolates reported in Mexico are generally associated with DTU I. We presented a case of a prolonged cutaneous lesion in a Mexican man, caused by DTU II in coinfection with Bacillus velezensis and Corynebacterium sp. The patient assessment included a complete clinical history, physical exam, laboratory tests, and a skin biopsy. In the facial tissues, intracellular parasites were revealed. The PCR tests were positive for T. cruzi in tissue and blood samples. DNA satellite sequencing was correlated with the DTU II. The initial serological tests reported negative results. However, four months later, two serological tests reported positive results. These exams were performed in different health centers. Mexico is considered an endemic area for CD; nevertheless, this is just the second cutaneous case associated with a DTU different from DTU-I noted in this country. From an ecological point of view, this fact suggests a geographical expansion of DTU II and an association with atypical skin manifestations. Further studies should be conducted to understand this exciting association between DTU-II and prolonged cutaneous expression in humans.

Long-term infection passaging of Human Adenovirus 36 in monkey kidney cells

ABSTRACT Human Adenovirus 36 (HAdV-36) has been related to diverse effects on metabolism and may attenuate the lipid accumulation in kidneys with increased adiposity. Some of these effects would be related to viral persistence. However, until now, a model of persistent in vitro infection by HAdV-36 is unknown. In this study, we examined the cells of the Vero lineage to explore their permissiveness to long-term HAdV-36 infection. HAdV-36 was productively replicated in Vero cells and maintained long-term infection for up to 35 cell passages. A subculture was obtained from the cells that survived the primary infection at a low MOI (0.5). The production of the extracellular infectious virus with titers ranging from 104 to 106 TCID50/mL and DNA-bearing cells was detected. In long-term infected cells, the intracellular distribution of viral antigen was demonstrated by performing immunolocalization (IFI) and expression of cell-viral antigen in 50% of cells by flow cytometry, using anti-HAdV-36 hyperimmune rabbit serum. Furthermore, E1a and E4orf1 genes in long-term infected passages showed a decreasing trend. Our preliminary results reveal that renal epithelial monkey cells are permissive for the productive infection of HAdV-36. Vero cell culture long-term infection might be a promising model for addressing the fundamental aspects of the HAdV-36 biology that cannot reveal broadly-used cultures, which do not maintain long-term infection in primary or transformed cells.

Identification of α-L-fucosidase (ALFuc) of Blastocystis sp. subtypes ST1, ST2 and ST3

ABSTRACT Blastocystis sp. is a common intestinal microorganism. The α-L-fucosidase (ALFuc) is an enzyme long associated with the colonization of the gut microbiota. However, this enzyme has not been experimentally identified in Blastocystis cultures. The objective of the present study was to identify ALFuc in supernatants of axenic cultures of Blastocystis subtype (ST)1 ATCC-50177 and ATCC-50610 and to compare predicted ALFuc proteins of alfuc genes in sequenced STs1-3 isolates in human Blastocystis carriers. Excretion/secretion (Es/p) and cell lysate proteins were obtained by processing Blastocystis ATCC cultures and submitting them to SDS-PAGE and immunoblotting. In addition, 18 fecal samples from symptomatic Blastocystis human carriers were analyzed by sequencing of amplification products for subtyping. A complete identification of the alfuc gene and phylogenetic analysis were performed. Immunoblotting showed that the amplified band corresponding to ALFuc (~51 kDa) was recognized only in the ES/p. Furthermore, prediction analysis of ALFuc 3D structures revealed that the domain α-L-fucosidase and the GH29 family's catalytic sites were conserved; interestingly, the galactose-binding domain was recognized only in ST1 and ST2. The phylogenetic inferences of ALFuc showed that STs1-3 were clearly identifiable and grouped into specific clusters. Our results show, for the first time through experimental data that ALFuc is a secretion product of Blastocystis sp., which could have a relevant role during intestinal colonization; however, further studies are required to clarify this condition. Furthermore, the alfuc gene is a promising candidate for a phylogenetic marker, as it shows a conserved classification with the SSU-rDNA gene.

Seroprevalence of human Trypanosoma cruzi infection in the North of Estado de Mexico

Abstract INTRODUCTION: Chagas disease is a neglected public health problem in Mexico; however, detailed studies to determine the seroprevalence in some states have not been performed. METHODS: A total 1,504 human serum from thirteen communities in Estado de Mexico, were analyzed with three diagnostics techniques. RESULTS: The overall seroprevalence was 9.1%, with high prevalence among people aged 51-60 years, while people aged 0-29 years were seronegative against T. cruzi. CONCLUSIONS: Our data demonstrated the seroprevalence of T. cruzi in the North of the Estado de Mexico, an area considered as non-endemic; however, epidemiological conditions necessary for natural transmission were found.