Turlock-like bunyavirus associated with encephalomyelitis and myocarditis in an ostrich chick

Emerging orthobunyaviruses associated with CNS disease

The Orthobunyavirus genus comprises a wide range of arthropod-borne viruses which are prevalent worldwide and commonly associated with central nervous system (CNS) disease in humans and other vertebrates. Several orthobunyaviruses have recently emerged and increasingly more will likely do so in the future. Despite this large number, an overview of these viruses is currently lacking, making it challenging to determine importance from a One Health perspective. Causality is a key feature of determining importance, yet classical tools are unfit to evaluate the causality of orthobunyaviral CNS disease. Therefore, we aimed to provide an overview of orthobunyaviral CNS disease in vertebrates and objectify the causality strength of each virus. In total, we identified 27 orthobunyaviruses described in literature to be associated with CNS disease. Ten were associated with disease in multiple host species of which seven included humans. Seven viruses were associated with both congenital and postnatal CNS disease. CNS disease-associated orthobunyaviruses were spread across all known Orthobunyavirus serogroups by phylogenetic analyses. Taken together, these results indicate that orthobunyaviruses may have a common tendency to infect the CNS of vertebrates. Next, we developed six tailor-made causality indicators and evaluated the causality strength of each of the identified orthobunyaviruses. Nine viruses had a 'strong' causality score and were deemed causal. Eight had a 'moderate' and ten a 'weak' causality score. Notably, there was a lack of case-control studies, which was only available for one virus. We, therefore, stress the importance of proper case-control studies as a fundamental aspect of proving causality. This comprehensible overview can be used to identify orthobunyaviruses which may be considered causal, reveal research gaps for viruses with moderate to low causality scores, and provide a framework to evaluate the causality of orthobunyaviruses that may newly emerge in the future.

Infection and propagation of Crimean-Congo hemorrhagic fever virus in embryonated chicken eggs

The embryonated chicken egg (ECE) provides a convenient, space-saving incubator for the cultivation of many kinds of animal viruses where the egg can be easily observed for viral replication throughout the development of the chicken embryo. Within the family Bunyaviridae, the embryonated egg has been used as a host system for many viruses such as Rift Valley fever virus and Akabane virus. The current study was conducted to determine the cultivation of Crimean-Congo hemorrhagic fever virus (CCHFV) in ECE. Four-day-old eggs were infected with CCHFV via the yolk sac route and harvested embryonic tissues and amino-allantoic fluid (AAF) that were used for virus passage and viral RNA (vRNA) detection. Quantification of vRNA copies was performed by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Our study indicated that CCHFV caused the death of the embryonated egg in a dose-dependent manner and the 50% egg infectious dose (EID50) was determined to be 6.47×10(5) copies/egg. CCHFV replicated and passaged well in the egg and high viral loads were detected both in embryonic tissue (10(9-10) copies/g) and AAF (10(7-9) copies/ml) of the embryonated egg. Thus, ECE could be used for viral cultivation and preservation, and as a potential host infection model for the study of the pathogenesis of CCHFV.

Congestive Heart Failure in 6 African Grey Parrots (Psittacus e erithacus)

Six African grey parrots ( Psittacus e erithacus) were diagnosed with cardiomyopathy and congestive heart failure based on gross and microscopic findings. Ages ranged from 15 days to 8 years, and 5 of 6 parrots were either neonates or juveniles at the time of diagnosis. Two neonates and 2 juveniles came from the same breeding aviary; the 2 juveniles were born to the same breeding pair. The 2 other parrots were kept as pets. Clinical signs included distention of the coelomic cavity (4 of 6), rales (3 of 6), weakness (4 of 6), bradyarrhythmia (1 of 6), growth retardation (1 of 6), crop stasis (1 of 6), and regurgitation (1 of 6). Three parrots were euthanized and 3 died. Gross findings included cardiomegaly due to biventricular, right-, or left-sided cardiomyopathy (6 of 6); coelomic effusion (6 of 6); whitish or yellow foci in the liver (6 of 6); atrophy of the liver (particularly, the left lobe; 5 of 6); reddened or grey lungs (5 of 6); subcutaneous edema (2 of 6); hydropericardium (1 of 6); and bilateral thyroid gland enlargement (1 of 6). Relevant microscopic findings included passive hepatic congestion (6 of 6) and pulmonary congestion (2 of 6), lymphocytic thyroiditis (2 of 6), and diffuse thyroid follicular hyperplasia (2 of 6). Microscopically, the heart was unremarkable (2 of 6) or had mild lymphocytic myocarditis (2 of 6), mild multifocal cytoplasmic vacuolation of cardiomyocytes (2 of 6), mild lymphocytic myocardial (Purkinje cell) ganglioneuritis (1 of 6), and mild multifocal interstitial fibrosis and nuclear hypertrophy of cardiomyocytes (1 of 6). One parrot had concurrent proventricular dilatation disease (systemic ganglioneuritis). The cause of cardiomyopathy in these parrots was not determined.