A New Clade of Insect-Specific Flaviviruses from Australian Anopheles Mosquitoes Displays Species-Specific Host Restriction.

Flaviviruses are arthropod-borne viruses found worldwide and are responsible for significant human and veterinary diseases, including dengue, Zika, and West Nile fever. Some flaviviruses are insect specific and replicate only in mosquitoes. We report a genetically divergent group of insect-specific flaviviruses from Anopheles mosquitoes that do not replicate in arthropod cell lines or heterologous Anopheles species, exhibiting unprecedented specialization for their host species. Determination of the complete sequences of the RNA genomes of three of these viruses, Karumba virus (KRBV), Haslams Creek virus, and Mac Peak virus (McPV), that are found in high prevalence in some Anopheles mosquito populations and detection of virus-specific proteins, replicative double-stranded RNA, and small interfering RNA responses in the host mosquito species provided strong evidence of a functional replicating virus in the mosquito midgut. Analysis of nucleotide composition in the KRBV and McPV sequences also revealed a pattern consistent with the virus evolving to replicate only in insects. These findings represent a significant advance in our knowledge of mosquito-borne flavivirus ecology, host restriction, and evolution. IMPORTANCE Flaviviruses like dengue, Zika, or West Nile virus infect millions of people each year and are transmitted to humans via infected-mosquito bites. A subset of flaviviruses can only replicate in the mosquito host, and recent studies have shown that some can interfere with pathogenic flaviviruses in mosquitoes and limit the replication and transmission of the latter. The insect-specific flaviviruses (ISFs) reported here form a new Anopheles mosquito-associated clade separate from the Aedes- and Culex-associated ISF clades. The identification of distinct clades for each mosquito genus provides new insights into the evolution and ecology of flaviviruses. One of these viruses was shown to replicate in the midgut of the mosquito host and exhibit the most specialized host restriction reported to date for ISFs. Understanding this unprecedented host restriction in ISFs could help identify the mechanisms involved in the evolution of flaviviruses and their emergence as mosquito-borne pathogens.

A novel insect-specific flavivirus replicates only in Aedes-derived cells and persists at high prevalence in wild Aedes vigilax populations in Sydney, Australia.

To date, insect-specific flaviviruses (ISFs) have only been isolated from mosquitoes and increasing evidence suggests that ISFs may affect the transmission of pathogenic flaviviruses. To investigate the diversity and prevalence of ISFs in Australian mosquitoes, samples from various regions were screened for flaviviruses by ELISA and RT-PCR. Thirty-eight pools of Aedes vigilax from Sydney in 2007 yielded isolates of a novel flavivirus, named Parramatta River virus (PaRV). Sequencing of the viral RNA genome revealed it was closely related to Hanko virus with 62.3% nucleotide identity over the open reading frame. PaRV failed to grow in vertebrate cells, with only Aedes-derived mosquito cell lines permissive to replication, suggesting a narrow host range. 2014 collections revealed that PaRV had persisted in A. vigilax populations in Sydney, with 88% of pools positive. Further investigations into its mode of transmission and potential to influence vector competence of A. vigilax for pathogenic viruses are warranted.

Aneurysmal degeneration of the donor artery after vascular access.

OBJECTIVE: This retrospective study analyzed the characteristics, potential risks, and therapeutic options of true aneurysms of the donor artery in arteriovenous fistulas (AVFs) for dialysis access. METHODS: We retrospectively collected data of patients with aneurysmal degeneration (AD) after AVF creation from surgeons who were members of the French Society for Vascular Access, treated from January 2006 to May 2011. The study excluded patients with pseudoaneurysms. Patient demographics, type of access, aneurysm characteristics, symptoms, treatment, and follow-up were recorded. RESULTS: Seven men and three women (mean age, 38.1 ± 5.3 years) were identified with AD (mean diameter, 44.5; range, 24-80 mm) Mean duration of access was 83.6 ± 48.8 months. Diagnosis of AD was at 117.5 ± 53.8 months after access creation. The initial access was radiocephalic, six; ulnobasilic, one; brachiocephalic, two; and brachiobasilic, one. Three patients had two successive accesses: one brachioaxillary polytetrafluoroethylene (PTFE) graft and two proximalizations of a failed radiocephalic AVF. Symptoms were pain and swelling, four; pain related to total thrombosis without signs of ischemia, two; median nerve compression, two; pain related to contained rupture, one; and subacute ischemia due to embolic occlusion of both radial and interosseous arteries, one. AD location was brachial, seven; axillary, one; radial, one; and ulnar, one. Eight patients underwent surgical aneurysm excision associated with interposition bypass using great saphenous vein, two; basilic vein, one; PTFE, three; Dacron, one; and allograft, one. Two patients needed secondary PTFE bypass because of progression of AD to the inflow artery and dilatation of the venous bypass. With a mean follow-up of 20.3 ± 17 months, all bypasses but one remained patent. CONCLUSIONS: AD is a rare but significant complication of vascular access. Surgical correction should be discussed in most cases due to potential complications. After resection, the choice of reconstructive conduit is not straightforward.