Stunned Silence: Gene Expression Programs in Human Cells Infected with Monkeypox or Vaccinia Virus

Poxviruses use an arsenal of molecular weapons to evade detection and disarm host immune responses. We used DNA microarrays to investigate the gene expression responses to infection by monkeypox virus (MPV), an emerging human pathogen, and Vaccinia virus (VAC), a widely used model and vaccine organism, in primary human macrophages, primary human fibroblasts and HeLa cells. Even as the overwhelmingly infected cells approached their demise, with extensive cytopathic changes, their gene expression programs appeared almost oblivious to poxvirus infection. Although killed (gamma-irradiated) MPV potently induced a transcriptional program characteristic of the interferon response, no such response was observed during infection with either live MPV or VAC. Moreover, while the gene expression response of infected cells to stimulation with ionomycin plus phorbol 12-myristate 13-acetate (PMA), or poly (I-C) was largely unimpaired by infection with MPV, a cluster of pro-inflammatory genes were a notable exception. Poly(I-C) induction of genes involved in alerting the innate immune system to the infectious threat, including TNF-alpha, IL-1 alpha and beta, CCL5 and IL-6, were suppressed by infection with live MPV. Thus, MPV selectively inhibits expression of genes with critical roles in cell-signaling pathways that activate innate immune responses, as part of its strategy for stealthy infection

Prevalence of Epistasis in the Evolution of Influenza A Surface Proteins

The surface proteins of human influenza A viruses experience positive selection to escape both human immunity and, more recently, antiviral drug treatments. In bacteria and viruses, immune-escape and drug-resistant phenotypes often appear through a combination of several mutations that have epistatic effects on pathogen fitness. However, the extent and structure of epistasis in influenza viral proteins have not been systematically investigated. Here, we develop a novel statistical method to detect positive epistasis between pairs of sites in a protein, based on the observed temporal patterns of sequence evolution. The method rests on the simple idea that a substitution at one site should rapidly follow a substitution at another site if the sites are positively epistatic. We apply this method to the surface proteins hemagglutinin and neuraminidase of influenza A virus subtypes H3N2 and H1N1. Compared to a non-epistatic null distribution, we detect substantial amounts of epistasis and determine the identities of putatively epistatic pairs of sites. In particular, using sequence data alone, our method identifies epistatic interactions between specific sites in neuraminidase that have recently been demonstrated, in vitro, to confer resistance to the drug oseltamivir; these epistatic interactions are responsible for widespread drug resistance among H1N1 viruses circulating today. This experimental validation demonstrates the predictive power of our method to identify epistatic sites of importance for viral adaptation and public health. We conclude that epistasis plays a large role in shaping the molecular evolution of influenza viruses. In particular, sites with , which would normally not be identified as positively selected, can facilitate viral adaptation through epistatic interactions with their partner sites. The knowledge of specific interactions among sites in influenza proteins may help us to predict the course of antigenic evolution and, consequently, to select more appropriate vaccines and drugs

The α-ketoglutarate dehydrogenase complex in cancer metabolic plasticity

Deregulated metabolism is a well-established hallmark of cancer. At the hub of various metabolic pathways deeply integrated within mitochondrial functions, the α-ketoglutarate dehydrogenase complex represents a major modulator of electron transport chain activity and tricarboxylic acid cycle (TCA) flux, and is a pivotal enzyme in the metabolic reprogramming following a cancer cell’s change in bioenergetic requirements. By contributing to the control of α-ketoglutarate levels, dynamics, and oxidation state, the α-ketoglutarate dehydrogenase is also essential in modulating the epigenetic landscape of cancer cells. In this review, we will discuss the manifold roles that this TCA enzyme and its substrate play in cancer

Esterase-3 polymorphism in the sugarcane borer Diatraea saccharalis (Lepidoptera, Pyralidae)

The migration rate of esterases and their substrate specificity for 4-methylumbelliferyl esters (acetate, propionate, and butyrate) and alpha- and beta-naphthyl esters were analyzed in Diatraea saccharalis by starch gel electrophoresis. Substrate preference of esterases was observed with Est-2 and Est-8 isozymes showing substrate specificity for 4-methylumbelliferyl esters and Est-4 isozyme showing specificity for 4-methylumbelliferyl butyrate and alpha-naphthyl butyrate. Allele variation was detected at the Est-3 locus. Two alleles, Est-3F and Est-3S, were identified in pupae with fluorogenic and ester-naphthyl substrates. Chi-square analysis showed no differences between the observed genotypic frequencies and those expected on the basis of Hardy-Weinberg frequencies for the Est-3 locus (chi² = 2.4; p < 0.01). The negative value for the Wright's fixation index (F = -0.2096) calculated for the D. saccharalis population maintained under laboratory conditions indicates an excess of heterozygotes, however, the observed Hardy-Weinberg equilibrium indicates that in the laboratory the population of D. saccharalis behaved as if the moth were randomly mating in nature. The high level of heterozygosity at the Est-3 locus indicates also that this esterase may be a good genetic marker for studies of natural D. saccharalis populations

Desenvolvimento da broca-das-cucurbitáceas em diferentes tipos de substratos alimentares Development of melonworm on different feeding substrates

Aspectos biológicos de Diaphania nitidalis foram estudados sob dietas natural e artificial em condições de laboratório, à temperatura de 25±1ºC, umidade relativa de 70±10% e fotofase de 14 horas. Como dieta natural foi utilizada abóbora 'Jacaré', pepino 'Japonês' e abobrinha 'Caserta' e, como artificial, a dieta utilizada em criações de Diatraea saccharalis, broca da cana-de-açúcar. As lagartas de D. nitidalis foram inoculadas nos diferentes tipos de substratos e criadas por todo o ciclo. Ocorreu diferença significativa entre a maioria dos parâmetros testados dentro dos tratamentos, sendo as dietas à base de abóbora e artificial as que proporcionaram maior potencial biótico para criação de D. nitidalis. Pela facilidade de aquisição dos ingredientes e manipulação dos insetos, a dieta artificial se torna mais eficaz para criação massal dessa espécie em laboratório.<br>The aim of this research was to evaluate the biological behaviour of melonworm at different natural and artificial diet under laboratory conditions (25ºC, 70% RH, 14 h photofase). Squash 'Jacaré', cucumber 'Japonês' and zucchini 'Caserta' were used as natural substrates compared to na artificial diet developed for the sugarcane borer (Diatraea saccharalis). The caterpillars were inoculated in each substrate and reared for a full cycle. The biological parameters were different among treatments. An artificial diet and squash cv. Jacaré substrate showed higher performance for the multiplication of D. nitidalis. The artificial diet is recommended because it is easy to obtain the ingredients and nultiply this insect under laboratory conditions