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

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.

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.

Myiasis caused by Dermatobia hominis in Mexico: morphological and molecular identification using the cytochrome oxidase I gene.

Myiasis caused by Dermatobia hominis , the human botfly, is frequent in the Americas, however, scarce morphological and molecular information exist regarding this dipteran. We describe three cases in urban areas of Mexico were D. hominis is not endemic. Morphological and genetic identification were performed using the cytochrome oxidase I as a molecular marker. The mitochondrial cytochrome oxidase I gene is useful for inferring the genetic divergence of D. hominis .

Establishment of respiratory syncytial virus persistence in cell lines: association with defective interfering particles.

Defective interfering particles (DIP) have frequently been advanced to explain the persistence of virus in vitro. However, DIP involvement in the establishment of respiratory syncytial virus (RSV) persistence in cell lines has not been documented. We report establishment of RSV persistence in human epithelial larynx (HEp-2) and lung (H358) cell lines by infection with RSV enriched with DIP. Viral persistence in HEp-2 and H358 has been stably maintained for >3 years without apparent cytopathic effect or periodic crises. Persistent cultures resisted superinfection with the original virus and no cyclic variations in infectious virus and DIP yields were observed. During passages, low levels of infectious RSV and defined species of DIP were produced. Moreover, 80-90% of the cells exhibited viral antigen. Persistence in H358 cells was established with a buoyant density band containing DIP and infectious virus obtained from a H358 persistently infected culture. Thus, DIP are required for establishment of RSV persistence cultures in human epithelial cell lines; however, DIP per se are not able to establish persistence.