Phylogenetic and phenotypic characterization of Burkholderia pseudomallei isolates from Ghana reveals a novel sequence type and common phenotypes.

Melioidosis is a potentially severe disease caused by the gram-negative soil-dwelling bacterium called Burkholderia pseudomallei. The true breadth of the distribution of this tropical pathogen is starting to emerge with environmental and clinical isolates frequently characterized in new countries and regions. Even so, isolates, clinical cases, and genetic data from the continent of Africa remain scant. We previously confirmed the presence of B. pseudomallei in the environment of Ghana, unmasking a new area of endemicity for this pathogen. Here, we describe the genetic characteristics of isolates obtained from that environmental survey. Twenty-one isolates were subjected to whole genome sequencing and found to represent three discrete sequence types (ST), one of which was novel, and designated ST2058. Phylogenetic analysis places this novel isolate within a B. pseudomallei clade that includes genomes derived from the Americas, although it is closely related to a sub-clade that includes isolates from Africa. Importantly, phenotypic characterization demonstrates common features including API 20NE profiles and B. pseudomallei CPS to support existing diagnostics, and susceptibility to standard of care antibiotics often used in the clinical management of melioidosis. These findings add to our knowledge about the presence and distribution of B. pseudomallei in Africa and represent the first published genomes out of Ghana.

Genomic Surveillance of Rabies Virus in Georgian Canines.

Rabies is a fatal zoonosis that is considered a re-emerging infectious disease. Although rabies remains endemic in canines throughout much of the world, vaccination programs have essentially eliminated dog rabies in the Americas and much of Europe. However, despite the goal of eliminating dog rabies in the European Union by 2020, sporadic cases of dog rabies still occur in Eastern Europe, including Georgia. To assess the genetic diversity of the strains recently circulating in Georgia, we sequenced seventy-eight RABV-positive samples from the brain tissues of rabid dogs and jackals using Illumina short-read sequencing of total RNA shotgun libraries. Seventy-seven RABV genomes were successfully assembled and annotated, with seventy-four of them reaching the coding-complete status. Phylogenetic analyses of the nucleoprotein (N) and attachment glycoprotein (G) genes placed all the assembled genomes into the Cosmopolitan clade, consistent with the Georgian origin of the samples. An amino acid alignment of the G glycoprotein ectodomain identified twelve different sequences for this domain among the samples. Only one of the ectodomain groups contained a residue change in an antigenic site, an R264H change in the G5 antigenic site. Three isolates were cultured, and these were found to be efficiently neutralized by the human monoclonal antibody A6. Overall, our data show that recently circulating RABV isolates from Georgian canines are predominantly closely related phylogroup I viruses of the Cosmopolitan clade. Current human rabies vaccines should offer protection against infection by Georgian canine RABVs. The genomes have been deposited in GenBank (accessions: OQ603609-OQ603685).

CAUSES AND TRENDS OF HARBOR SEAL (PHOCA VITULINA) MORTALITY ALONG THE BRITISH COLUMBIA COAST, CANADA, 2012-2020.

A retrospective study was conducted to categorize and describe the causes of mortality in harbor seals (Phoca vitulina) along the British Columbia coast that presented to the Vancouver Aquarium Marine Mammal Rescue Centre (MMR) for rehabilitation from 2012 to 2020. Medical records for 1,279 predominantly perinatal live-stranded harbor seals recovered in this region were reviewed. Approximately 20.0% (256 individuals; 137 males, 118 females, 1 unknown) of these animals died while at MMR. Infectious disease was the most common cause of death, accounting for 60.5% of mortality across all age classes. This was followed by nonanthropogenic trauma (7.1%), metabolic illness (5.4%), nutritional deficiency (5.0%), parasitic illness (5.0%), congenital disorders (2.5%), and human-associated trauma (0.4%). Pups were the most common age class (87.4%) amongst mortalities and predominantly died of an infectious process (62.5%). Phocid herpesvirus-1 infection was identified in 18.9% of the mortalities, with the highest prevalence occurring in 2019 (30.8%). Fungal disease was detected in six seals: three cases of pulmonary mycosis due to Cryptococcus gattii and three cases consistent with mucormycosis. In six cases, mortality was attributed to congenital disorders. Two of these cases involved axial skeletal malformities that are not currently described in the literature. This is the first study to describe the causes of mortality in harbor seals undergoing rehabilitation in British Columbia.

Identification of Mosquito Bloodmeals Collected in Diverse Habitats in Malaysian Borneo Using COI Barcoding.

Land cover and land use change (LCLUC) acts as a catalyst for spillover of arthropod-borne pathogens into novel hosts by shifting host and vector diversity, abundance, and distribution, ultimately reshaping host-vector interactions. Identification of bloodmeals from wild-caught mosquitoes provides insight into host utilization of particular species in particular land cover types, and hence their potential role in pathogen maintenance and spillover. Here, we collected 134 blood-engorged mosquitoes comprising 10 taxa across 9 land cover types in Sarawak, Malaysian Borneo, a region experiencing intense LCLUC and concomitant spillover of arthropod-borne pathogens. Host sources of blood were successfully identified for 116 (87%) mosquitoes using cytochrome oxidase subunit I (COI) barcoding. A diverse range of hosts were identified, including reptiles, amphibians, birds, and mammals. Sixteen engorged Aedes albopictus, a major vector of dengue virus, were collected from seven land cover types and found to feed exclusively on humans (73%) and boar (27%). Culex tritaeniohynchus (n = 2), Cx. gelidus (n = 3), and Cx. quiquefasciatus (n = 3), vectors of Japanese encephalitis virus, fed on humans and pigs in the rural built-up land cover, creating potential transmission networks between these species. Our data support the use of COI barcoding to characterize mosquito-host networks in a biodiversity hotspot.

Corrigendum: RNA-Seq Comparison of Larval and Adult Malpighian Tubules of the Yellow Fever Mosquito Aedes aegypti Reveals Life Stage-Specific Changes in Renal Function.

[This corrects the article on p. 283 in vol. 8, PMID: 28536536.].

RNA-Seq Comparison of Larval and Adult Malpighian Tubules of the Yellow Fever Mosquito Aedes aegypti Reveals Life Stage-Specific Changes in Renal Function.

Introduction: The life history of Aedes aegypti presents diverse challenges to its diuretic system. During the larval and pupal life stages mosquitoes are aquatic. With the emergence of the adult they become terrestrial. This shifts the organism within minutes from an aquatic environment to a terrestrial environment where dehydration has to be avoided. In addition, female mosquitoes take large blood meals, which present an entirely new set of challenges to salt and water homeostasis. Methods: To determine differences in gene expression associated with these different life stages, we performed an RNA-seq analysis of the main diuretic tissue in A. aegypti, the Malpighian tubules. We compared transcript abundance in 4th instar larvae to that of adult females and analyzed the data with a focus on transcripts that encode proteins potentially involved in diuresis, like water and solute channels as well as ion transporters. We compared our results against the model of potassium- and sodium chloride excretion in the Malpighian tubules proposed by Hine et al. (2014), which involves at least eight ion transporters and a proton-pump. Results: We found 3,421 of a total number of 17,478 (19.6%) unique transcripts with a P < 0.05 and at least a 2.5 fold change in expression levels between the two groups. We identified two novel transporter genes that are highly expressed in the adult Malpighian tubules, which have not previously been part of the transport model in this species and may play important roles in diuresis. We also identified candidates for hypothesized sodium and chloride channels. Detoxification genes were generally higher expressed in larvae. Significance: This study represents the first comparison of Malpighian tubule transcriptomes between larval and adult A. aegypti mosquitoes, highlighting key differences in their renal systems that arise as they transform from an aquatic filter-feeding larval stage to a terrestrial, blood-feeding adult stage.

The effect of the radio-protective agents ethanol, trimethylglycine, and beer on survival of X-ray-sterilized male Aedes aegypti.

BACKGROUND: Sterile Insect Technique (SIT) has been successfully implemented to control, and in some cases, eradicate, dipteran insect populations. SIT has great potential as a mosquito control method. Different sterilization methods have been used on mosquitoes ranging from chemosterilization to genetically modified sterile male mosquito strains; however, sterilization with ionizing radiation is the method of choice for effective sterilization of male insects for most species. The lack of gentle radiation methods has resulted in significant complications when SIT has been applied to mosquitoes. Several studies report that irradiating mosquitoes resulted in a decrease in longevity and mating success compared to unirradiated males. The present study explored new protocols for mosquito sterilization with ionizing radiation that minimized detrimental effects on the longevity of irradiated males. METHODS: We tested three compounds that have been shown to act as radioprotectors in the mouse model system - ethanol, trimethylglycine, and beer. Male Aedes aegypti were treated with one of three chosen potential radioprotectors and were subsequently irradiated with identical doses of long-wavelength X-rays. We evaluated the effect of these radioprotectors on the longevity of male mosquito after irradiation. RESULTS: We found that X-ray irradiation with an absorbed dose of 1.17 gy confers complete sterility. Irradiation with this dose significantly shortened the lifespan of male mosquitoes and all three radioprotectors tested significantly enhanced the lifespan of irradiated mosquito males. CONCLUSION: Our results suggest that treatment with ethanol, beer, or trimethylglycine before irradiation can be used to enhance longevity in mosquitoes.