Genomic diversity in a population of Spodoptera frugiperda nucleopolyhedrovirus.

Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) represents a strong candidate to develop environmental-friendly pesticides against the fall armyworm (Spodoptera frugiperda), a widespread pest that poses a severe threat to different crops around the world. To date, SfMNPV genomic diversity of different isolates has been mainly studied by means of restriction pattern analyses and by sequencing of the egt region. Here, the genomic diversity present inside an isolate of SfMNPV was explored using high-throughput sequencing for the first time. We identified 704 intrahost single nucleotide variants, from which 184 are nonsynonymous mutations distributed among 82 different coding sequences. We detected several structural variants affecting SfMNPV genome, including two previously reported deletions inside the egt region. A comparative analysis between polymorphisms present in different SfMNPV isolates and our intraisolate diversity data suggests that coding regions with higher genetic diversity are associated with oral infectivity or unknown functions. In this context, through molecular evolution studies we provide evidence of diversifying selection acting on sf29, a putative collagenase which could contribute to the oral infectivity of SfMNPV. Overall, our results contribute to deepen our understanding of the coevolution between SfMNPV and the fall armyworm and will be useful to improve the applicability of this virus as a biological control agent.

Characterization of a Novel Thermostable Enzyme from Thermus sp. 2.9 with Phospholipase and Acyltransferase Activities.

Phospholipases are classified in different enzyme families according to the ester bond they cleave within phospholipids. The use of phospholipases in industrial processes has prompted the search for new enzymes with differential properties. A gene encoding a novel phospholipase (PLP_2.9) was identified in the genome of the thermophilic strain Thermus sp. 2.9. The analysis of the primary sequence unveiled a patatin-like domain. The alignment of the amino acid sequence of PLP_2.9 to other bacterial patatin-related proteins showed that the four blocks characteristic of this type of phospholipases and the amino acids representing the catalytic dyad are conserved in this protein. PLP_2.9 was overexpressed in Escherichia coli and the purified enzyme was characterized biochemically. PLP_2.9 hydrolyzed p-nitrophenyl palmitate at alkaline pH over a wide range of temperatures (55-80°C), showing high thermostability. PLP_2.9 displayed phospholipase A and acyltransferase activities on egg yolk phosphatidylcholine. Due to its high thermostability, PLP_2.9 has potential applications as a catalyst in several industrial processes.

Genome of Epinotia aporema granulovirus (EpapGV), a polyorganotropic fast killing betabaculovirus with a novel thymidylate kinase gene.

BACKGROUND: Epinotia aporema (Lepidoptera: Tortricidae) is an important pest of legume crops in South America. Epinotia aporema granulovirus (EpapGV) is a baculovirus that causes a polyorganotropic infection in the host larva. Its high pathogenicity and host specificity make EpapGV an excellent candidate to be used as a biological control agent. RESULTS: The genome of Epinotia aporema granulovirus (EpapGV) was sequenced and analyzed. Its circular double-stranded DNA genome is 119,082 bp in length and codes for 133 putative genes. It contains the 31 baculovirus core genes and a set of 19 genes that are GV exclusive. Seventeen ORFs were unique to EpapGV in comparison with other baculoviruses. Of these, 16 found no homologues in GenBank, and one encoded a thymidylate kinase. Analysis of nucleotide sequence repeats revealed the presence of 16 homologous regions (hrs) interspersed throughout the genome. Each hr was characterized by the presence of 1 to 3 clustered imperfect palindromes which are similar to previously described palindromes of tortricid-specific GVs. Also, one of the hrs (hr4) has flanking sequences suggestive of a putative non-hr ori. Interestingly, two more complex hrs were found in opposite loci, dividing the circular dsDNA genome in two halves. Gene synteny maps showed the great colinearity of sequenced GVs, being EpapGV the most dissimilar as it has a 20 kb-long gene block inversion. Phylogenetic study performed with 31 core genes of 58 baculoviral genomes suggests that EpapGV is the baculovirus isolate closest to the putative common ancestor of tortricid specific betabaculoviruses. CONCLUSIONS: This study, along with previous characterization of EpapGV infection, is useful for the better understanding of the pathology caused by this virus and its potential utilization as a bioinsecticide.