Seroprevalence of malignant catarrhal fever-related gammaherpesviruses in domestic ruminants in Turkey

First reported case in an Irish flock of MCF- like systemic necrotizing vasculitis in sheep associated with ovine herpesvirus 2

BACKGROUND

Ovine gammaherpesvirus 2 (OvHV-2) is the causative agent of sheep associated malignant catarrhal fever (MCF). As sheep are the adapted host for OvHV-2, it is generally presumed that infection is not associated with disease in this species. However, a recent case review combined in-situ hybridisation, PCR and histopathology and correlated the viral distribution with systemic necrotizing vasculitis and concluded OvHV-2 was the likely agent responsible for sporadic, MCF-like vascular disease in sheep.

CASE PRESENTATION

Using similar methods this case study reports on the findings of the first reported cases in an Irish Flock of MCF- like systemic necrotizing vasculitis in sheep associated with OvHV-2. Sheep A, a 16-month-old Texel-cross hogget displayed signs of ill- thrift, Sheep B, a nine-month-old Belclare-cross lamb, was found dead having displayed no obvious symptoms. Both cases occurred on the same farm, however the animals were not related. Lymphohistiocytic vasculitis of various tissues was the predominant histopathological finding in both animals.

CONCLUSION

By combining histopathology, PCR and in-situ hybridisation results, MCF- like systemic necrotizing vasculitis associated with OvHV-2 has been diagnosed for the first time in an Irish flock.

Detection and characterisation of sheep-associated malignant catarrhal fever infection from ruminants by using tegument and gB gene sequences of OvHV-2

In this study, positive blood and organ samples were obtained from different mixed herds of sheep and cattle against ovine herpesvirus 2 (OvHV-2) infection. Target-positive DNA was sequenced and compared with worldwide distributed OvHV-2 sequences. Tegument gene (422 base pairs) and glycoprotein B (gB) gene (2800 base pairs) amplicons of OvHV-2 genome were used for understanding of epidemiology of malignant catarrhal fever (MCF) infection in Turkey. The results of nucleotide sequencing of polymerase chain reaction (PCR) products indicated presence of sheep-associated form for MCF infection in Turkey. Although the obtained sequences were genetically different from each other, it was found that genetic variations were limited.

Two Different Macaviruses, ovine herpesvirus-2 and caprine herpesvirus-2, behave differently in water buffaloes than in cattle or in their respective reservoir species

The ongoing global spread of "exotic" farm animals, such as water buffaloes, which carry their native sets of viruses, may bear unknown risks for the animals, into whose ecological niches the former are introduced and vice versa. Here, we report on the occurrence of malignant catarrhal fever (MCF) on Swiss farms, where "exotic" water buffaloes were kept together with "native" animals, i.e. cattle, sheep, and goats. In the first farm with 56 water buffaloes, eight cases of MCF due to ovine herpesvirus-2 (OvHV-2) were noted, whereas additional ten water buffaloes were subclinically infected with either OvHV-2 or caprine herpesvirus-2 (CpHV-2). On the second farm, 13 water buffaloes were infected with CpHV-2 and two of those succumbed to MCF. In neither farm, any of the two viruses were detected in cattle, but the Macaviruses were present at high prevalence among their original host species, sheep and goats, respectively. On the third farm, sheep were kept well separated from water buffaloes and OvHV-2 was not transmitted to the buffaloes, despite of high prevalence of the virus among the sheep. Macavirus DNA was frequently detected in the nasal secretions of virus-positive animals and in one instance OvHV-2 was transmitted vertically to an unborn water buffalo calf. Thus, water buffaloes seem to be more susceptible than cattle to infection with either Macavirus; however, MCF did not develop as frequently. Therefore, water buffaloes seem to represent an interesting intermediate-type host for Macaviruses. Consequently, water buffaloes in their native, tropic environments may be vulnerable and endangered to viruses that originate from seemingly healthy, imported sheep and goats.

Molecular characterisation of ovine herpesvirus type 2 (OvHV-2) in Turkey

In this study, the physical examination of 22 cattle revealed clinical signs of malignant catarrhal fever (MCF). Peripheral blood leukocyte (PBL) samples of the 22 cattle, and nasal (n = 7) and conjunctival (n = 9) swab samples from 16 sheep from two different farms, were taken for laboratory examination. The clinical diagnosis of MCF in cows was confirmed by the detection of ovine herpesvirus type 2 (OvHV-2) DNA by polymerase chain reaction (PCR). OvHV-2 DNA was detected by nested-PCR in PBL of one cow with clinical signs and nasal (1/7)-conjunctival(1/9) swab samples of two sheep housed in the same barn. According to the sequence analysis, three slightly divergent viruses were detected. The results indicate the need for additional research in different regions of Turkey to gain a better understanding of the incidence of MCF and its implications for the livestock industry.

A serologic survey of viral infections in captive ungulates in Turkish zoos

Zoos and zoologic gardens make optimal environments for interspecies transmission of viral infections. There are seven zoos and several small zoologic collections in Turkey. This study aimed to determine the current status of viral infections in captive ungulates living in these environments. Blood samples were taken from 163 captive animals from two zoos. There were 39 Cameroon sheep (Ovis ammon f aries), 11 Barbary sheep (Ammotragus lervia), 57 pygmy goats (Capra hircus), 9 Angora goats (Capra hircus), 21 mountain goats (Capra aegagrus-aegagrus), 7 llamas (Lama glama), 8 Persian goitred gazelle (Gazella subgutturosa subgutturosa), 7 Caspian red deer (Cervus elaphus maral), 2 fallow deer (Dama dama), and 2 camels (Camelus dromedarius). Antibodies against bovine viral diarrhea virus (BVDV), bovine herpesvirus-1 (BHV-1), bovine adenoviruses (BAV-1 and -3), parainfluenzavirus 3 (PI-3), and bluetongue viruses (BTV-4 and -9) were investigated using the virus neutralization test, and malignant catarrhal fever (MCF) antibodies were screened by ELISA. All animals were negative for BVDV and BHV-1 antibodies. Seroprevalence of BAV-1, BAV-3, PI-3, BRSV, BT-4, BT-9, and MCF were detected as follows: 46.6%, 60.1%, 0.6%, 7.3%, 1.8%, 1.2%, and 51.6%, respectively. Seroprevalence of BAVs and MCF were more common than all other viruses (P < 0.0001). Ten sheep (37.0%), 48 goats (84.2), and 1 Ilama (14.2%) were the only species positive for MCF antibodies. Prevalence of BRSV and MCF antibodies were found to be significantly higher in goats than in sheep. BTV antibodies were detected both in Cameroon sheep and mountain goats and suggest that zoo animals are at risk for BTV in endemic regions.