Highly divergent dengue virus type 1 genotype sets a new distance record.

Dengue viruses (DENVs) are the leading cause of mosquito-borne viral disease of humans. They exist in both endemic and sylvatic ecotypes. In 2014, a viremic patient who had recently visited the rainforests of Brunei returned to Australia displaying symptoms consistent with DENV infection. A unique DENV strain was subsequently isolated from the patient, which we propose belongs to a new genotype within DENV serotype 1 (DENV-1). Bayesian evolutionary phylogenetic analysis suggests that the putative sylvatic DENV-1 Brunei 2014 (Brun2014) is the most divergent DENV-1 yet recorded and increases the time to the most recent common ancestor (MRCA) for DENV-1 from ≈120 years to ≈315 years. DENV-1 classification of the Brun2014 strain was further supported by monoclonal antibody serotyping data. Phenotypic characterization demonstrated that Brun2014 replication rates in mosquito cells and infection rates in Aedes aegypti mosquitoes were not significantly different from an epidemic DENV-1 strain. Given its ability to cause human illness and infect Ae. aegypti, potential urban spillover and clinical disease from further Brun2014 transmission cannot be discounted.

Australian bat lyssavirus infection in two horses.

In May 2013, the first cases of Australian bat lyssavirus infections in domestic animals were identified in Australia. Two horses (filly-H1 and gelding-H2) were infected with the Yellow-bellied sheathtail bat (YBST) variant of Australian bat lyssavirus (ABLV). The horses presented with neurological signs, pyrexia and progressing ataxia. Intra-cytoplasmic inclusion bodies (Negri bodies) were detected in some Purkinje neurons in haematoxylin and eosin (H&E) stained sections from the brain of one of the two infected horses (H2) by histological examination. A morphological diagnosis of sub-acute moderate non-suppurative, predominantly angiocentric, meningo-encephalomyelitis of viral aetiology was made. The presumptive diagnosis of ABLV infection was confirmed by the positive testing of the affected brain tissue from (H2) in a range of laboratory tests including fluorescent antibody test (FAT) and real-time PCR targeting the nucleocapsid (N) gene. Retrospective testing of the oral swab from (H1) in the real-time PCR also returned a positive result. The FAT and immunohistochemistry (IHC) revealed an abundance of ABLV antigen throughout the examined brain sections. ABLV was isolated from the brain (H2) and oral swab/saliva (H1) in the neuroblastoma cell line (MNA). Alignment of the genome sequence revealed a 97.7% identity with the YBST ABLV strain.