Human virome in nasopharynx and tracheal secretion samples

Evaluation of extraction and enrichment methods for recovery of respiratory RNA viruses in a metagenomics approach

Viral metagenomics is increasingly applied in viral detection and virome characterization. Different extraction and enrichment techniques may be adopted, however, reports on their effective influence on viral recovery is often conflicting. Using a three step enrichment steps, the effect of three extraction kits and the influence of DNase treatment with or without rRNA removal for respiratory RNA virus recovery from nasopharyngeal swab samples was evaluated. The viral cocktail containing six different RNA viruses pooled in equal volume were subjected to the different extraction and enrichment methods, sequenced using the Illumina MiSeq, and analysed using Genome Detective. The PureLink® Viral RNA/DNA Mini Kit (PureLink) was highly efficient with better recovery of all the viral agents in the cocktail. The use of rRNA treatment resulted in increased viral recovery with PureLink and QIAamp® Viral RNA Mini kit, while having comparable recovery rate as DNase only with the QIAamp® MinElute Virus Spin Kit. The observed low reads and genome coverage of some of the viruses could be attributed to their low abundance. Depending on sample matrix, extraction choice and enrichment strategy may influence recovery of respiratory RNA virus in metagenomics studies, therefore individual evaluation and adoption may be necessary for a robust result.

[Impact of hygienic and social distancing measures against SARS-CoV-2 on respiratory infections caused by other viruses]

OBJECTIVE

To control the pandemic caused by SARS-CoV-2, the implementation of social and hygienic confinement measures was determined in all countries. These measures reduce the circulation of most respiratory viruses that are transmitted preferentially by air and contact.

METHODS

The impact of these measures on non-Covid respiratory viruses during the period August-December 2020 and 2019 has been comparatively analyzed. To all nasopharyngeal aspirates that were negative against SARS-CoV-2 by RT-PCR and the suspicion of acute respiratory infection persisted, were subjected to a new RT-PCR that simultaneously and differentially amplifies 21 different respiratory viruses.

RESULTS

In the year of the pandemic, a 36.6% decrease was detected in the number of respiratory samples studied and 66% in their positivity in relation to 2019. All viruses showed reduction percentages of between 40-100%. The only viruses that circulated during and after national lockdown were rhinovirus (74.1%), adenovirus (10.1%), and enterovirus (9.6%).

CONCLUSIONS

The measures used to control the SARS-CoV-2 infection have also affected the community circulation of most respiratory viruses including influenza and respiratory syncytial virus.

Molecular and clinical characteristics related to rhinovirus infection in Brasília, Brazil

Introduction

Human rhinovirus (HRV) is one of the most common human viral pathogens related to infections of the upper and lower respiratory tract, which can result in bronchiolitis and pneumonia. However, the relevance of HRV in human health was under-estimated for long time due to the absence of molecular targets for influenza and influenza-like syndrome surveillance in Brasília, Brazil.

Objectives

The main objective of this study was analyze the clinical characteristics and outcomes of HRV infections in comparison with patients without HRV and other common respiratory viruses.

Materials and Methods

For this purpose, new specific primer sets were designed based on the high throughput sequencing analysis in previous study. These primers were used for HRV detection by RT-qPCR and Sanger sequencing of amplified cDNA of 5′ genomic region. The phylogenetic tree with representative HRV isolates was constructed using the Mega X software. Statistical analysis considering the patient profiles were performed using IBM SPSS program with non-parametric tests.

Results

The most prevalent virus in negative samples was rhinovirus (n = 40), including three rhinovirus species (rhinovirus A, B, and C). The odds ratio associated with HRV infection was 2.160 for patients younger than 2 years and 4.367 for people living in rural areas. The multiple analysis showed lower chance of patients with HRV presenting respiratory distress.

Conclusion

In this study, it was reported the predominance of rhinoviruses in cases of respiratory illness for negative patients for the influenza and influenza-like syndrome surveillance, being rhinorrhea, the most significant symptom associated with the disease.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42770-020-00411-0.

Human Coronaviruses and Other Respiratory Viruses: Underestimated Opportunistic Pathogens of the Central Nervous System?

Respiratory viruses infect the human upper respiratory tract, mostly causing mild diseases. However, in vulnerable populations, such as newborns, infants, the elderly and immune-compromised individuals, these opportunistic pathogens can also affect the lower respiratory tract, causing a more severe disease (e.g., pneumonia). Respiratory viruses can also exacerbate asthma and lead to various types of respiratory distress syndromes. Furthermore, as they can adapt fast and cross the species barrier, some of these pathogens, like influenza A and SARS-CoV, have occasionally caused epidemics or pandemics, and were associated with more serious clinical diseases and even mortality. For a few decades now, data reported in the scientific literature has also demonstrated that several respiratory viruses have neuroinvasive capacities, since they can spread from the respiratory tract to the central nervous system (CNS). Viruses infecting human CNS cells could then cause different types of encephalopathy, including encephalitis, and long-term neurological diseases. Like other well-recognized neuroinvasive human viruses, respiratory viruses may damage the CNS as a result of misdirected host immune responses that could be associated with autoimmunity in susceptible individuals (virus-induced neuro-immunopathology) and/or viral replication, which directly causes damage to CNS cells (virus-induced neuropathology). The etiological agent of several neurological disorders remains unidentified. Opportunistic human respiratory pathogens could be associated with the triggering or the exacerbation of these disorders whose etiology remains poorly understood. Herein, we present a global portrait of some of the most prevalent or emerging human respiratory viruses that have been associated with possible pathogenic processes in CNS infection, with a special emphasis on human coronaviruses.