Insights on Transmission, Spread, and Possible Endemization of Selected Arboviruses in Israel-Interim Results from Five-Year Surveillance.

Outbreaks of arthropod-borne (arbo) viruses that infect livestock impact the health and welfare of domestic and wild animals are often responsible for significant economic losses in livestock production. Surveillance and early warning systems effectively predict the emergence and re-emergence of arboviral disease. This paper presents the interim results of five years monitoring the exposure of sentinel naïve heifers and Culicoides biting midges (Diptera; Ceratopogonidae) to bovine ephemeral fever virus (BEFV), Simbu serogroup viruses, bluetongue viruses (BTV), and epizootic hemorrhagic disease viruses (EHDV). The data were collected from 11 dairy farms situated within eight different geographical regions in Israel. The results indicate that cattle in Israel are affected by all four viruses from the early summer onward. The investigated viruses exhibit unique site-specific profiles in both ruminants and vectors. The potential of several vectors to transmit these viruses and lack of cross-protection to re-infection with multiple serotypes (BTV and EHDV) or species (Simbu serogroup viruses) highlights some likely mechanisms that may play a role in these viruses' maintenance cycle and possible endemization in our region.

Characterization of bluetongue virus serotype 28.

Bluetongue virus (Reoviridae; Orbivirus, BTV), which is usually transmitted by biting midges, affects wild and domestic ruminants worldwide, thereby causing an economically important disease. Recently, a putative new BTV strain was isolated from contaminated vaccine batches. In this study, we investigated the genomic and clinical characteristics of this isolate, provisionally designated BTV-28. Phylogenetic analysis of BTV-28 segment 2 (Seg-2) showed that it is related to Seg-2 from BTV serotypes 4, 10, 11, 17, 20 and 24, sharing 64%-66% identity in nucleotide sequences (nt) and 59%-62% in amino acid (aa) sequences of BTV VP2. BTV-28 Seg-6 is related to the newly reported XJ1407 BTV isolate, sharing 76.70% nt and 90.87% aa sequence identity. Seg-5 was most closely related to a South African BTV-4 strain, and all other segments showed close similarity to BTV-26. Experimental infection by injection of 6-month-old ewes caused clinical signs in all injected animals, lasting from 2 to 3 days to several weeks post-infection, including high body temperature, conjunctivitis, nasal discharge and rhinitis, facial oedema, oral hyperaemia, coronitis, cough, depression and tongue cyanosis. Naïve control animals, placed together with the infected sheep, displayed clinical signs and were positive for viral RNA, but their acute disease phase was shorter than that of BTV-injected ewes. Control animals that were kept in a separated pen did not display any clinical signs and were negative for viral RNA presence throughout the experiment. Seroconversion was observed in the injected and in one of the two contact-infected animals. These findings demonstrate that BTV-28 infection of sheep can result in clinical manifestation, and the clinical signs detected in the contact animals suggest that it might be directly transmitted between the mammalian hosts.

Complete Genome Sequence of a Bovine Ephemeral Fever Virus Isolate from Israel.

Here, we report the first complete genome of a bovine ephemeral fever virus (BEFV) isolate from an infected bovine in Israel. The genome shares 95.3% identity with a Turkish genomic sequence but contains α3 and γ open reading frames that are truncated compared to those of existing BEFV genome sequences.