Poxvirus sensitivity of a novel diploid sheep embryonic heart cell line.

Lumpy skin disease virus (LSDV), camelpox virus (CPV), and orf virus (ORFV) are members of the family Poxviridae. These viruses are usually isolated or produced in embryonated eggs or primary cells because continuous cell lines are less sensitive to infection. Disadvantages of the use of eggs or primary cells include limited availability, potential endogenous contaminants, and a limited ability to perform multiple passages. In this study, we developed a diploid cell culture from sheep embryonic hearts (EHs) and demonstrated its high proliferative and long-term storage capacities. In addition, we demonstrated its sensitivity to representatives of three genera of the family Poxviridae: Capripoxvirus (LSDV), Orthopoxvirus (CPV), and Parapoxvirus (ORFV). The cell culture had a doubling time of 24 h and reached 40 passages with satisfactory yield. This is comparable to that observed in primary lamb testis (LT) cells at passage 5 (P5). After infection, each poxvirus titer was 7.0-7.6 log TCID50/mL for up to five passages and approximately 6.8, 6.4, and 5.6 for the three viruses at P6-P25, P30, and P40, respectively. The sensitivity of sheep EH cells to poxvirus infection did not decrease after long-term storage in liquid nitrogen and was higher than that of primary LT cells, which are used for capripoxvirus and parapoxvirus detection and growth, and Vero cells, which are used for orthopoxvirus detection and growth. Thus, EH diploid cells are useful for poxvirus isolation and production without embryonated eggs or primary cells.

Experimental infection of indigenous North African goats with goatpox virus.

BACKGROUND: Goatpox is a viral disease caused by infection with goatpox virus (GTPV) of the genus Capripoxvirus, Poxviridae family. Capripoxviruses cause serious disease to livestock and contribute to huge economic losses. Goatpox and sheeppox are endemic to Africa, particularly north of the Equator, the Middle East and many parts of Asia. GTPV and sheeppox virus are considered host-specific; however, both strains can cause clinical disease in either goats or sheep with more severe disease in the homologous species and mild or sub-clinical infection in the other. Goatpox has never been reported in Morocco, Algeria or Tunisia despite the huge population of goats living in proximity with sheep in those countries. To evaluate the susceptibility and pathogenicity of indigenous North African goats to GTPV infection, we experimentally inoculated eight locally bred goats with a virulent Vietnamese isolate of GTPV. Two uninfected goats were kept as controls. Clinical examination was carried out daily and blood was sampled for virology and for investigating the antibody response. After necropsy, tissues were collected and assessed for viral DNA using real-time PCR. RESULTS: Following the experimental infection, all inoculated goats displayed clinical signs characteristic of goatpox including varying degrees of hyperthermia, loss of appetite, inactivity and cutaneous lesions. The infection severely affected three of the infected animals while moderate to mild disease was noticed in the remaining goats. A high antibody response was developed. High viral DNA loads were detected in skin crusts and nodules, and subcutaneous tissue at the injection site with cycle threshold (Ct) values ranging from 14.6 to 22.9, while lower viral loads were found in liver and lung (Ct = 35.7 and 35.1). The results confirmed subcutaneous tropism of the virus. CONCLUSION: Clinical signs of goatpox were reproduced in indigenous North African goats and confirmed a high susceptibility of the North African goat breed to GTPV infection. A clinical scoring system is proposed that can be applied in GTPV vaccine efficacy studies.