Hepatitis C virus (HCV) quasispecies constitute a dynamic population in a continuous process of variation and selection. To investigate effect of the immune system on the genetic variability of HCV, we compared the hypervariable region 1 (HVR1) of immunosuppressed patients with chronic renal failure (CRF group) to immunocompetent patients with HCV chronic infection (control group). The HVR1 from ten samples of each group was amplified, cloned and sequenced. The HCV quasispecies from the control group had a higher frequency of variable sites in HVR1 (83.9 % vs 59.3 %, p < 0.05), as well as a greater diversity within (intra-patient) and between samples, compared to the CRF group. The clustering of the majority of the quasispecies of the CRF group in the phylogenetic tree also showed the limited diversity of the quasispecies in immunosuppressed patients. Moreover, a higher variability of amino acids at positions 384, 386, 391, 394, 397, 398, 400, 405 and 410 was observed in the control group than in the CRF group, which showed a greater variability only at position 388 (p < 0.05). These data corroborates the hypothesis that the major selective pressure factor is the immune system, which promotes a high degree of diversity in the viral progeny and contributes to a constant evolution of HCV.
Root-knot nematodes (RKN- Meloidogyne genus) present extensive challenges to soybean crop. The soybean line (PI 595099) is known to be resistant against specific strains and races of nematode species, thus its differential gene expression analysis can lead to a comprehensive gene expression profiling in the incompatible soybean-RKN interaction. Even though many disease resistance genes have been studied, little has been reported about phytohormone crosstalk on modulation of ROS signaling during soybean-RKN interaction.
Early promoter activity of HPV-58 molecular variants isolated from high-grade cervical lesions in Brazil was compared. Luciferase reporter assays were conducted in C33 cells transfected with the complete long control region of 3 molecular variants of HPV-58 as well as HPV-58, -18 or -16 prototypes. The HPV-58 prototype and Bsb-329 and Bsb-367 variants showed a promoter activity similar to that of HPV-16, but lower than that of Bsb-295 and HPV-18. The introduction of the Bsb-295 7788 mutation into the HPV-58 prototype resulted in the enhancement of transcription closer to Bsb-295 and HPV-18. These results could impact the expression of E6 and E7 viral oncogenes.
More than 100 HPV types have been described, 13 of which are classified as high-risk due to their association with the development of cervical cancer. The intratype genomic diversity of HPV-16 and -18 has been studied extensively, while little data have been generated for other less common high-risk types. The present study explores the nucleotide variability and phylogeny of the high-risk HPV-31, -33, -35, -52, and -58, in samples from Central Brazil. For this purpose, the LCR and the E6 and L1 genes were sequenced. Several variants of these HPV types were detected, some of which have been detected in other parts of the world. Furthermore, new variants of all types examined were characterized in a total of 13 new variants. Based on the E6 and L1 sequences, variants were described comprising conservative and non-conservative amino acid changes. For phylogenetic tree construction, samples characterized in this study were compared to others described and submitted to GenBank previously. The phylogenetic analysis of HPV-31, -33, -35, and -58 isolates did not reveal ethnic or geographical clustering as observed previously for HPV-16 and -18. HPV-35 analysis showed a dichotomic branching characteristic of viral subtypes. Interestingly, four clusters relative to the analysis of HPV-52 isolates were identified, two of which could be classified as Asian and European branches. The genomic characterization of HPV variants is crucial for understanding the intrinsic geographical relatedness and biological differences of these viruses and contributes further to studies on their infectivity and pathogenicity.
Soybean is an important crop for Brazilian agribusiness. However, many factors can limit its production, especially root-knot nematode infection. Studies on the mechanisms employed by the resistant soybean genotypes to prevent infection by these nematodes are of great interest for breeders. For these reasons, the aim of this work is to characterize the transcriptome of soybean line PI 595099-Meloidogyne javanica interaction through expression analysis. Two cDNA libraries were obtained using a pool of RNA from PI 595099 uninfected and M. javanica (J(2)) infected roots, collected at 6, 12, 24, 48, 96, 144 and 192 h after inoculation. Around 800 ESTs (Expressed Sequence Tags) were sequenced and clustered into 195 clusters. In silico subtraction analysis identified eleven differentially expressed genes encoding putative proteins sharing amino acid sequence similarities by using BlastX: metallothionein, SLAH4 (SLAC1 Homologue 4), SLAH1 (SLAC1 Homologue 1), zinc-finger proteins, AN1-type proteins, auxin-repressed proteins, thioredoxin and nuclear transport factor 2 (NTF-2). Other genes were also found exclusively in nematode stressed soybean roots, such as NAC domain-containing proteins, MADS-box proteins, SOC1 (suppressor of overexpression of constans 1) proteins, thioredoxin-like protein 4-Coumarate-CoA ligase and the transcription factor (TF) MYBZ2. Among the genes identified in non-stressed roots only were Ser/Thr protein kinases, wound-induced basic protein, ethylene-responsive family protein, metallothionein-like protein cysteine proteinase inhibitor (cystatin) and Putative Kunitz trypsin protease inhibitor. An understanding of the roles of these differentially expressed genes will provide insights into the resistance mechanisms and candidate genes involved in soybean-M. javanica interaction and contribute to more effective control of this pathogen.
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