SARS-CoV-2 rapidly evolves lineage-specific phenotypic differences when passaged repeatedly in immune-naïve mice.

The persistence of SARS-CoV-2 despite the development of vaccines and a degree of herd immunity is partly due to viral evolution reducing vaccine and treatment efficacy. Serial infections of wild-type (WT) SARS-CoV-2 in Balb/c mice yield mouse-adapted strains with greater infectivity and mortality. We investigate if passaging unmodified B.1.351 (Beta) and B.1.617.2 (Delta) 20 times in K18-ACE2 mice, expressing the human ACE2 receptor, in a BSL-3 laboratory without selective pressures, drives human health-relevant evolution and if evolution is lineage-dependent. Late-passage virus causes more severe disease, at organism and lung tissue scales, with late-passage Delta demonstrating antibody resistance and interferon suppression. This resistance co-occurs with a de novo spike S371F mutation, linked with both traits. S371F, an Omicron-characteristic mutation, is co-inherited at times with spike E1182G per Nanopore sequencing, existing in different within-sample viral variants at others. Both S371F and E1182G are linked to mammalian GOLGA7 and ZDHHC5 interactions, which mediate viral-cell entry and antiviral response. This study demonstrates SARS-CoV-2's tendency to evolve with phenotypic consequences, its evolution varying by lineage, and suggests non-dominant quasi-species contribution.

Zika virus induces oxidative stress and decreases antioxidant enzyme activities in vitro and in vivo.

The first outbreak of Zika virus (ZIKV) infection in the Americas, especially in Brazil, was reported in 2015. Fever, headache, rash, and conjunctivitis are the common symptoms of ZIKV infection. Unexpected clinical outcomes, such as microcephaly and Guillain-Barré syndrome, have also been reported. The recent spread of ZIKV and its association with severe illness has created an urgent need to understand its pathogenesis and find potential therapeutic targets. Studies show that some viruses, including Flavivirus, trigger oxidative stress, which affects cellular metabolism, viral cycle, and pathogenesis. However, the role of oxidative stress in ZIKV infection needs to be investigated. Here, we analyzed ZIKV infection-triggered oxidative stress and modified antioxidant enzyme activities. U87-MG and HepG2 cells were infected to measure reactive oxygen species (ROS), malondialdehyde (MDA), and carbonyl protein levels, the activities of superoxide dismutase (SOD) and catalase (CAT), and the activation of nuclear factor erythroid 2p45-related factor 2 (Nrf2). ZIKV infection induced a significant increase in ROS, lipid peroxidation, and protein carbonylation products and a significant decrease in SOD and CAT activities accompanied by inhibition of Nrf2 activation in both cell lines. Further, MDA and carbonyl protein levels and SOD and CAT activities were evaluated in the brain and liver of ZIKV-infected C57BL/6 mice, and oxidative stress associated with antioxidant depletion was also found to occur in vivo. Together, our findings indicate the potential use of antioxidants as a novel therapeutic approach to Zika disease, and future studies in this direction are warranted.

Isolation and genomic characterization of a new mimivirus of lineage B from a Brazilian river.

Since its discovery, the first identified giant virus associated with amoebae, Acanthamoeba polyphaga mimivirus (APMV), has been rigorously studied to understand the structural and genomic complexity of this virus. In this work, we report the isolation and genomic characterization of a new mimivirus of lineage B, named "Borely moumouvirus". This new virus exhibits a structure and replicative cycle similar to those of other members of the family Mimiviridae. The genome of the new isolate is a linear double-strand DNA molecule of ~1.0 Mb, containing over 900 open reading frames. Genome annotation highlighted different translation system components encoded in the DNA of Borely moumouvirus, including aminoacyl-tRNA synthetases, translation factors, and tRNA molecules, in a distribution similar to that in other lineage B mimiviruses. Pan-genome analysis indicated an increase in the genetic arsenal of this group of viruses, showing that the family Mimiviridae is still expanding. Furthermore, phylogenetic analysis has shown that Borely moumouvirus is closely related to moumouvirus australiensis. This is the first mimivirus lineage B isolated from Brazilian territory to be characterized. Further prospecting studies are necessary for us to better understand the diversity of these viruses so a better classification system can be established.

The multiple origins of proteins present in tupanvirus particles.

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.

Dengue outbreaks in Divinopolis, south-eastern Brazil and the geographic and climatic distribution of Aedes albopictus and Aedes aegypti in 2011-2012.

OBJECTIVE: To entomologically monitor Aedes spp. and correlate the presence of these vectors with the recent epidemic of dengue in Divinopolis, Minas Gerais State, Brazil. METHODS: Ovitraps were installed at 44 points in the city, covering six urban areas, from May 2011 to May 2012. After collection, the eggs were incubated until hatching. In the 4th stage of development, the larvae were classified as Ae. aegypti or Ae. albopictus. RESULTS: In total, 25 633 Aedes spp. eggs were collected. February was the month with the highest incidence, with 5635 eggs collected and a hatching rate of 46.7%. Ae. aegypti eggs had the highest hatching rate, at 72.3%, whereas Ae. albopictus eggs had 27.7%. Climate and population density influenced the number of eggs found. Indicators of vector presence were positively correlated with the occurrence of dengue cases. CONCLUSION: These data reinforce the need for entomological studies, highlight the relevance of Ae. albopictus as a possible disease vector and demonstrate its adaptation. Ae. albopictus, most commonly found in forested areas, comprised a substantial proportion of the urban mosquito population.