Population genomic analysis of Cryptococcus Brazilian isolates reveals an African type subclade distribution

The genomes of a large number of Cryptococcus neoformans isolates have been sequenced and analyzed in recent years. These genomes have been used to understand the global population structure of this opportunistic pathogen. However, only a small number of South American isolates have been considered in these studies, and the population structure of C. neoformans in this part of the world remains elusive. Here, we analyzed the genomic sequences of 53 Brazilian Cryptococcus isolates and deciphered the C. neoformans population structure in this country. Our data reveal an African-like structure that suggested repeated intercontinental transports from Africa to South America. We also identified a mutator phenotype in one VNBII Brazilian isolate, exemplifying how fast-evolving isolates can shape the Cryptococcus population structure. Finally, phenotypic analyses revealed wide diversity but not lineage specificity in the expression of classical virulence traits within the set of isolates.

Population Genomic Analysis of Cryptococcus Brazilian Strains Reveals an African Type Subclades Distribution

The genome of a large number of Cryptococcus neoformans isolates has been sequenced and analyzed in recent years. These genomes have been used to understand the global population structure of this opportunistic pathogen. However, only a small number of South American isolates have been considered in these studies, and the population structure of C. neoformans in this part of the world remains evasive. Here, we analyzed the genomic sequences of 53 Brazilian Cryptococcus isolates and deciphered the C. neoformans population structure in this country. Our data reveal an African-like structure that suggesting repeated and privileged intercontinental transports from Africa to South America. We also identified a mutator phenotype in one VNBII Brazilian isolate, exemplifying how fast-evolving isolates can shape the Cryptococcus population structure. Finally, phenotypic analyses revealed wide diversity but not lineage specificity in the expression of classical virulence traits within the set of isolates.

Assessment of Immunogenicity and Efficacy of a Zika Vaccine Using Modified Vaccinia Ankara Virus as Carriers

Zika virus (ZIKV) is an emerging mosquito-borne flavivirus that has spread to more than 70 countries worldwide since 2015. Despite active research, there are currently no licensed vaccines or therapeutics. We have previously reported the development of various adenoviral vectored vaccine candidates (ChAdOx1 ZIKV) with the ability to stimulate effective immunity in mice and provide protection upon a ZIKV challenge model, using a non-adjuvanted single vaccination approach. In this study, we constructed various modified vaccinia Ankara (MVA) viruses to express the ZIKV Envelope (E) with modifications on the precursor membrane (prM) or on the C-terminus envelope transmembrane domain (TM), similar to our ChAdOx1 vaccine candidates. MVA-ZIKV vaccine candidates were evaluated as a non-adjuvanted single vaccination regimen against a ZIKV Brazilian isolate, using viraemia as the correlate of protection. Here, we report the induction of a modest level of anti-ZIKV E antibodies by all MVA vectored vaccines and sub-optimal efficacy in a ZIKV challenge model. Our results indicate the requirement of additional strategies when using MVA-ZIKV vaccines to afford sterile protection upon a non-adjuvanted and single vaccination regime.

Morphological and Physiological Responses of Sugarcane to Leifsonia xyli subsp. xyli Infection

Ratoon stunt, caused by the bacterium Leifsonia xyli subsp. xyli, is one of the major sugarcane diseases worldwide. The objectives of this study were to determine the variation in morphology and DNA sequence of L. xyli subsp. xyli strains isolated in China, to compare the changes that occurred in vascular ultrastructure and levels of endogenous hormone abscisic acid (ABA), auxins (indoleacetic acid [IAA]), and gibberellic acids (GA3) in sugarcane stalks. Experiments were also conducted with two sugarcane varieties, ‘ROC22’ and ‘Badila’, in the greenhouse to understand the cytological and physiological mechanisms of L. xyli subsp. xyli–induced growth stunting. There were three treatments in the experiments: (i) healthy plants (L. xyli subsp. xyli–free plants), (ii) infected plants (L. xyli subsp. xyli–infected seedcanes treated with hot water, and (iii) infected plants (healthy seedcanes dipped in L. xyli subsp. xyli cell culture). The results showed that sequence coverage of a locally isolated strain, LxxGXBZ01, was 99.99%, and the average nucleotide identity between LxxGXBZ01 and the other well-characterized Brazilian isolate LxxCTCB07 was 93.61%. LxxGXBZ01 occurred in different sizes and shapes in xylem vessels of infected plants. In comparison with healthy stalks, the secondary walls of the vessel element in L. xyli subsp. xyli–infected stalks were degraded with uneven wall thickness, deformities, sticky substances, and electron-dense substances accumulated inside the cells. Compared with the healthy and hot-water treatments, the contents of IAA and GA3 were significantly lower, while that of ABA was significantly higher in the L. xyli subsp. xyli–infected stalks. The information obtained in this study will expand our understanding of ratoon stunt etiology and cytological and physiological bases of the disease manifestation.

The Impact of African and Brazilian Zika virus isolates on neuroprogenitors

In the last few months, an overwhelming number of people have been exposed to the Zika virus (ZIKV) in South and Central America. Here we showed, in vitro, that a Brazilian isolate impacts more severely murine neuronal progenitors and neurons than the African strain MR766. We found that the Brazilian isolate more pronouncedly inhibits neurite extension from neurospheres, alters their differentiation potential and causes neurons to have less and shorter processes. Comparing both lineages using a panel of inflammatory cytokines, we showed, with human neuroblastoma cells, that ZIKV induces the production of several inflammatory and chemotactic cytokines and once again, the Brazilian isolate had a more significant impact. Although much more needs to be studied regarding the association of ZIKV infection and brain damage during development, our study sheds some light into the differences between African and American lineages and the mechanisms by which the virus may be affecting neurogenesis.