The main explanation for HBsAg undetectability relies on the very low level of viremia observed. The single-amino-acid deletion found in the S protein cannot account for HBsAg detection failure, because the capture antibody of the assay used is targeted to a different sequence epitope (aa121-124). Meanwhile, CCA deletion may have impacted the virus replication efficiency since it affects the overlapping reverse transcriptase "finger" domain of the polymerase gene. These findings define this case as an acute primary OBI, confirming the existence of this condition. NAT with high sensitivity is the only screening enabling prevention of HBV transmission by transfusion in such cases.

ABSTRACT. The occurrence of Fusarium spp associated with pecan tree (Carya illinoinensis) diseases in Brazil has been observed in recent laboratory analyses in Rio Grande do Sul State. Thus, in this study, we i) obtained Fusarium isolates from plants with disease symptoms; ii) tested the pathogenicity of these Fusarium isolates to pecan; iii) characterized and grouped Fusarium isolates that were pathogenic to the pecan tree based on morphological characteristics; iv) identified Fusarium spp to the species complex level through TEF-1α sequencing; and v) compared the identification methods used in the study. Fifteen isolates collected from the inflorescences, roots, and Fusarium spp pathogenic to pecan tree seeds of symptomatic plants (leaf necrosis or root rot) were used for pathogenicity tests. Morphological characterization was conducted using only pathogenic isolates, for a total of 11 isolates, based on the mycelial growth rate, sporulation, colony pigmentation, and conidial length and width variables. Pathogenic isolates were grouped based on morphological characteristics, and molecular characterization was performed by sequencing TEF-1α genes. Pathogenic isolates belonging to the Fusarium chlamydosporum species complex, Fusarium graminearum species complex, Fusarium proliferatum, and Fusarium oxysporum were identified based on the TEF-1α region. Morphological characteristics were used to effectively differentiate isolates and group the isolates according to genetic similarity, particularly conidial width, which emerged as a key morphological descriptor in this study.

Cordia americana (L.) Gottschling & J. S. Mill. (guajuvira) is a forest species widely distributed in Brazil and represents environmental and economic importance due to the quality of its timber and use in reforestation. In order to evaluate the pathogenicity of Fusarium sp. associated with seeds, characterizing the isolates morphologically and molecularly in order to identify them on the species level, was obtained four fungal isolates that were inoculated in seeds to demonstrate their pathogenicity. The morphological characterization was performed using an identification key for the genus Fusarium and, for the molecular identification, genomic regions Internal Transcribed Spacer (ITS) were sequenced with its elongation factor 1 alpha (TEF1-α). The results of the molecular identification agreed with the morphological characterization and allowed to identify the species Fusarium acuminatum and Fusarium verticillioides,

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RESUMO Extratos vegetais podem auxiliar no controle de doenças de plantas, por sua atividade antimicrobiana ou pela ativação de mecanismos de defesa. Neste trabalho, objetivouse avaliar o efeito dos extratos aquosos de alho e alecrim INTRODUÇÃOA antracnose é uma das mais importantes doenças do feijoeiro, tendo como agente etiológico o fungo Colletotrichum lindemuthianum (Sacc. E Magnus) Scrib. Essa doença compromete o rendimento da cultura e a qualidade do produto final, por isso o uso de produtos químicos tornou-se uma das principais formas de controle. No entanto, torna-se indispensável investigar métodos alternativos para o controle de doenças de plantas que aliem eficiência, menor