Cygnet River Virus, a Novel Orthomyxovirus from Ducks, Australia

Abstract

A novel virus, designated Cygnet River virus (CyRV), was isolated in embryonated eggs from Muscovy ducks in South Australia. CyRV morphologically resembles arenaviruses; however, sequencing identified CyRV as an orthomyxovirus. The high mortality rate among ducks co-infected with salmonellae suggests that CyRV may be pathogenic, either alone or in concert with other infections.

Cyclic Avian Mass Mortality in the Northeastern United States Is Associated with a Novel Orthomyxovirus

“…All avian (Pekin duck, Japanese quail) and mammalian (human, African green monkey, rhesus macaque, Mexican free-tailed bat, Virginia opossum, American mink, cattle) cell lines tested were susceptible to infection and supported replication to various degrees (maximum titers of 10 6.15 to 10 8.02 PFU/ml). However, WFBV did not replicate in C6/36 cells derived from Aedes albopictus, similar to results reported for QFRV and JAV (23,64) as well as CyRV (34), demonstrating an in vitro host range barrier for Asian tiger mosquito cells in all tested quaranjaviruses. Phylogenetic analysis.…”

“…In 2010, a new orthomyxovirus designated Cygnet River virus (CyRV) was isolated during an outbreak of fatal disease in captive Muscovy ducks (Cairina moschata) on Kangaroo Island, South Australia (34). Remarkably, although the outbreak sites are approximately 17,000 km apart, genetic and antigenic comparisons between WFBV and CyRV (as shown here) demonstrate they may be geographical variants of the same virus.…”

“…However, the most intriguing finding was that WFBV was closely related to, and potentially appears to share common host and pathological properties with, the newly identified Cygnet River virus (CyRV), a novel orthomyxovirus isolated from an outbreak of clinical disease in captive Muscovy ducks (Cairina moschata) along the Cygnet River in Kangaroo Island, South Australia (34). Similar to the cyclic outbreaks involving WFBV in Cape Cod, the epizootic of CyRV was characterized by premonitory clinical signs such as lethargy and diarrhea, prominent histopathological lesions in the liver, and large-scale mortality in ducks (34). The apparent similarities between the two viruses were further extended, as comparisons of the complete matrix (M) proteins between WFBV and CyRV demonstrated an 89.0% amino acid identity (Fig.…”

“…2C), whether it is an opportunistic pathogen that becomes virulent only in concert with underlying conditions (e.g., malnutrition) or coinfections is uncertain but is currently being assessed in experimental trials. As the recovery of Salmonella from dead Muscovy ducks during the CyRV outbreak of 2010 suggests that clinical disease in virus-infected birds may be dependent upon the additive or synergistic effects of concurrent infections (34), investigation into the detection of other pathogens in association with WFBV infection, such as through metagenomic analysis of eider tissues, will also be a focus of future research. The observed epidemics of disease involving a novel orthomyxovirus in the United States warrants further study not only to better understand the underlying causes of these outbreaks but to also clarify the evolution, epidemiology, and ecology of these newly emerging orthomyxoviruses.…”

“…7C), most likely due to the short and limited number of sequences in the data set. Overall, it appears that the 12 orthomyxoviruses confirmed or suspected to be tick-borne can most likely be grouped into two defined genera: (i) Quaranjavirus, tentatively encompassing QRFV, JAV, LKCV, TLKV, CyRV, and WFBV, and (ii) Thogotovirus, tentatively encompassing THOV, DHOV (including Batken, a variant of DHOV), JOSV, Upolu virus (UPOV), Aransas Bay virus (ABV), and Araguari virus (ARAV) (23,34,(65)(66)(67)(68)(69).…”