ABSTRACT
For decades, viruses have been isolated primarily from humans and other organisms. Interestingly, one of the most complex sides of the virosphere was discovered using free-living amoebae as hosts. The discovery of giant viruses in the early twenty-first century opened a new chapter in the field of virology. Giant viruses are included in the phylum Nucleocytoviricota and harbor large and complex DNA genomes (up to 2.7 Mb) encoding genes never before seen in the virosphere and presenting gigantic particles (up to 1.5 µm). Different amoebae have been used to isolate and characterize a plethora of new viruses with exciting details about novel viral biology. Through distinct isolation techniques and metagenomics, the diversity and complexity of giant viruses have astonished the scientific community. Here, we discuss the latest findings on amoeba viruses and how using these single-celled organisms as hosts has revealed entities that have remained hidden in plain sight for ages.
Subject(s)
Amoeba , Giant Viruses , Viruses , DNA Viruses/genetics , Genome, Viral , Giant Viruses/genetics , Humans , Metagenomics , Phylogeny , Viruses/geneticsABSTRACT
Here, we propose the creation of the family "Yaraviridae", a new taxon to classify a virus infecting Acanthamoeba castellanii cells. Recently, we described the discovery of a new virus infecting free-living amoebae, yaravirus, which has features that strongly differ from those of all other viruses of amoebae described to date. Yaravirus particles are about 80 nm in diameter and have a dsDNA genome of ~45 kbp containing 74 ORFs, most of which (>90%) have no homologs in current databases. Together, these data support the creation of a new species ("Yaravirus brasiliense"), a new viral genus (here proposed as "Yaravirus"), and a new viral family (here proposed as "Yaraviridae") to classify yaravirus and other related viruses that may be described in the future. All of them are to be included into the existing realm Varidnaviria and the kingdom Bamfordvirae, due to the presence of a major capsid protein containing a double jelly-roll fold.
Subject(s)
Acanthamoeba castellanii , Capsid Proteins , DNA Viruses/genetics , Genome, ViralABSTRACT
The world is experiencing the worst global health crisis in recent decades since December/2019 due to a new pandemic coronavirus. The COVID-19 disease, caused by SARS-CoV-2, has resulted in more than 30 million cases and 950 thousand deaths worldwide as of September 21, 2020. Determining the extent of the virus on public surfaces is critical for understanding the potential risk of infection in these areas. In this study, we investigated the presence of SARS-CoV-2 RNA on public surfaces in a densely populated urban area in Brazil. Forty-nine of 933 samples tested positive (5.25%) for SARS-CoV-2 RNA, including samples collected from distinct material surfaces, including metal and concrete, and distinct places, mainly around hospital care units and public squares. Our data indicated the contamination of public surfaces by SARS-CoV-2, suggesting the circulation of infected patients and the risk of infection for the population. Constant monitoring of the virus in urban areas is required as a strategy to fight the pandemic and prevent further infections.
Subject(s)
COVID-19 , SARS-CoV-2 , Brazil/epidemiology , Humans , Pandemics , RNA, ViralABSTRACT
In the last few decades, the isolation of amoebae-infecting giant viruses has challenged established principles related to the definition of virus, their evolution, and their particle structures represented by a variety of shapes and sizes. Tupanviruses are one of the most recently described amoebae-infecting viruses and exhibit a peculiar morphology with a cylindrical tail attached to the capsid. Proteomic analysis of purified viral particles revealed that virions are composed of over one hundred proteins with different functions. The putative origin of these proteins had not yet been investigated. Here, we provide evidences for multiple origins of the proteins present in tupanvirus particles, wherein 20% originate from members of the archaea, bacteria and eukarya.
Subject(s)
Giant Viruses/chemistry , Giant Viruses/genetics , Proteome , Viral Proteins/genetics , Virion/chemistry , Amoeba/virology , Archaea/genetics , Bacteria/genetics , Eukaryota/genetics , Proteomics , Viral Proteins/chemistry , Virion/geneticsABSTRACT
BACKGROUND: Mimiviruses have been considered putative emerging pneumonia agents. Pneumonia is a leading cause of death related to infection throughout the world, with approximately 40% of cases presenting unknown etiology. Therefore, identifying new causative agents of community and nosocomial pneumonia is of major public health concern. OBJECTIVE: We evaluated the distribution of these viruses in samples collected from different environments of one of the largest hospitals in Brazilian Southeast. STUDY DESIGN: We analyzed, by molecular and virological approaches, the distribution of mimivirus in 242 samples collected from inanimate surfaces in different hospital facilities. RESULTS: A significant positivity of mimivirus in respiratory-isolation-facilities was observed (p<0.001). CONCLUSION: Although the role of mimivirus as etiological agents of pneumonia is still under investigation, our results demonstrates interesting correlations that strengthens the need for control over the occurrence of these viruses in hospital facilities.