Building a Sentiment Corpus of Tweets in Brazilian Portuguese

The large amount of data available in social media, forums and websites motivates researches in several areas of Natural Language Processing, such as sentiment analysis. The popularity of the area due to its subjective and semantic characteristics motivates research on novel methods and approaches for classification. Hence, there is a high demand for datasets on different domains and different languages. This paper introduces TweetSentBR, a sentiment corpora for Brazilian Portuguese manually annotated with 15.000 sentences on TV show domain. The sentences were labeled in three classes (positive, neutral and negative) by seven annotators, following literature guidelines for ensuring reliability on the annotation. We also ran baseline experiments on polarity classification using three machine learning methods, reaching 80.99% on F-Measure and 82.06% on accuracy in binary classification, and 59.85% F-Measure and 64.62% on accuracy on three point classification.Comment: Accepted for publication in 11th International Conference on Language Resources and Evaluation (LREC 2018

Transcriptional analysis of viral mRNAs reveals common transcription patterns in cells infected by five different filoviruses

<div><p>Filoviruses are notorious viral pathogens responsible for high-consequence diseases in humans and non-human primates. Transcription of filovirus mRNA shares several common features with transcription in other non-segmented negative-strand viruses, including differential expression of genes located across the viral genome. Transcriptional patterns of Ebola virus (EBOV) and Marburg virus (MARV) have been previously described using traditional, laborious methods, such as northern blots and in vivo labeling of viral mRNAs. More recently, however, the availability of the next generation sequencing (NGS) technology has offered a more straightforward approach to assess transcriptional patterns. In this report, we analyzed the transcription patterns of four ebolaviruses—EBOV, Sudan (SUDV), Bundibugyo (BDBV), and Reston (RESTV) viruses—in two different cell lines using standard NGS library preparation and sequencing protocols. In agreement with previous reports mainly focused on EBOV and MARV, the remaining filoviruses used in this study also showed a consistent transcription pattern, with only minor variations between the different viruses. We have also analyzed the proportions of the three mRNAs transcribed from the GP gene, which are characteristic of the genus <i>Ebolavirus</i> and encode the glycoprotein (GP), the soluble GP (sGP), and the small soluble GP (ssGP). In addition, we used NGS methodology to analyze the transcription pattern of two previously described recombinant MARV. This analysis allowed us to correct our construction design, and to make an improved version of the original MARV expressing reporter genes.</p></div

InDel variants at the canonical GP editing site.

<p>Huh7 and Mpg cells were infected with EBOV, SUDV, BDBV, or RESTV at moi = 0.1. Total RNA was harvested 3 dpi, and purified mRNAs were used to make NGS libraries. Variant detection was done using a minimum cut-off of 1%.</p

Optimization of support plasmid ratios for CCHFV rescue in BSR-T7/5.

<p>(A) BSR-T7/5 cells were transfected with 1 μg pT7-S, 2.5 μg pT7-M, 1 μg pT7-L, 0.66 μg pC-N, and 0.33 μg pC-L opti. Cell supernatants were collected and viral titers measured by determining TCID₅₀ at the indicated times post transfection. (B) In the experiments using 2:1 ratio of pC-N to pC-L opti, cells were transfected as in panel A except that 1 μg of pC-T7 was added to the transfection mix. In the experiment using a 19:1 pC-N:pC-L opti ratio, the same plasmid mix was used as for the 2:1 ratio, but with 0.95 μg of pC-N and 0.05 μg of pC-L opti. Error bars indicate means ± standard deviation. Statistical significance was evaluated using Student’s unpaired <i>t</i> test. Asterisk (*) indicates P < 0.05 at 3 days post transfection (2:1 versus 19:1). Dashed line indicates the limit of detection.</p

Recovery of Recombinant Crimean Congo Hemorrhagic Fever Virus Reveals a Function for Non-structural Glycoproteins Cleavage by Furin

<div><p>Crimean Congo hemorrhagic fever virus (CCHFV) is a negative-strand RNA virus of the family <i>Bunyaviridae</i> (genus: <i>Nairovirus</i>). In humans, CCHFV causes fever, hemorrhage, severe thrombocytopenia, and high fatality. A major impediment in precisely determining the basis of CCHFV’s high pathogenicity has been the lack of methodology to produce recombinant CCHFV. We developed a reverse genetics system based on transfecting plasmids into BSR-T7/5 and Huh7 cells. In our system, bacteriophage T7 RNA polymerase produced complementary RNA copies of the viral S, M, and L segments that were encapsidated with the support, in <i>trans</i>, of CCHFV nucleoprotein and L polymerase. The system was optimized to systematically recover high yields of infectious CCHFV. Additionally, we tested the ability of the system to produce specifically designed CCHFV mutants. The M segment encodes a polyprotein that is processed by host proprotein convertases (PCs), including the site-1 protease (S1P) and furin-like PCs. S1P and furin cleavages are necessary for producing the non-structural glycoprotein GP38, while S1P cleavage yields structural Gn. We studied the role of furin cleavage by rescuing a recombinant CCHFV encoding a virus glycoprotein precursor lacking a functional furin cleavage motif (RSKR mutated to ASKA). The ASKA mutation blocked glycoprotein precursor’s maturation to GP38, and Gn precursor’s maturation to Gn was slightly diminished. Furin cleavage was not essential for replication, as blocking furin cleavage resulted only in transient reduction of CCHFV titers, suggesting that either GP38 and/or decreased Gn maturation accounted for the reduced virion production. Our data demonstrate that nairoviruses can be produced by reverse genetics, and the utility of our system uncovered a function for furin cleavage. This viral rescue system could be further used to study the CCHFV replication cycle and facilitate the development of efficacious vaccines to counter this biological and public health threat.</p></div

Furin effect on CCHFV-WT and-ASKA growth.

<p>FD11 and FD11-Fur cells were infected with CCHFV-WT or CCHFV-ASKA (MOI = 0.1). Cell supernatants were collected daily, and RNA S-segment copy numbers and infectious virus titers were measured by qRT-PCR and TCID₅₀ determination, respectively. Means ± standard deviation (n = 3) are plotted. Statistical significance was evaluated using Student’s unpaired <i>t</i> test. Asterisk (*) indicates P < 0.05.</p

Growth kinetics of CCHFV derived from cDNA.

<p>(A) BSR-T7/5 and (B) A549 cells were infected with 0.001 of 50% tissue culture infective dose (TCID₅₀)/cell of cDNA-derived CCHFV (circles) or parental virus isolate from Nigeria (squares). Viral titers were measured daily. Dashed line indicates the limit of detection.</p

Effects of blocking furin cleavage on CCHFV glycoprotein maturation.

<p>(A) SW13 cells were infected with WT CCHFV or CCHFV-ASKA at MOI = 0.1, and immunoblots of structural proteins were performed on lysates collected 24 h post infection. Ratios of Gn:Pre and Gc:PreGc were obtained by densitometry of the bands (AlphaView; Alpha Innotech). (B) Immunoprecipitation of secreted non-structural proteins containing the GP38 domain with 6C11 mAb.</p

CCHFV M segment polyprotein processing.

<p>(A) Signal peptide (SP) and predicted transmembrane domains are indicated in yellow. Arrows indicate locations of cleavage motifs recognized by mammalian convertases. The RSKR motif (boxed) was mutated to ASKA to block processing. (B) Signal peptidase (SPase) cleavages result in production of Gn and Gc precursors (PreGn and PreGc). Binding regions of the anti-glycoprotein antibodies used in this study (7F5, Gn tail, 11E7, and 6C11) are also represented. (C) Mature glycoprotein products (GP160/85, GP38, Gn, and Gc) resulting from mammalian convertase cleavage. (D) S1P cleavage is required for the production of GP160/85 and Gn, while GP38 requires cleavage by both S1P and furin-like PCs. An unidentified mammalian convertase is required for PreGc maturation to Gc.</p

CCHFV rescue efficiency using varying ratios of plasmids producing complementary genome segments in BSR-T7/5.

<p>BSR-T7/5 cells were transfected with a total of 4.5 μg of pT7-S, pT7-M, and pT7-L at the indicated S:M:L ratios, together with 0.66 μg pC-N, 0.33 μg pC-L opti, and 1 μg pC-T7. Supernatants were collected 4 days after transfection, and viral titers were measured by TCID₅₀ determination. Dashed line indicates the limit of detection.</p