Replication and Release of Epizootic Haemorrhagic Disease Virus in BHK-21 Cells

Abstract

SUMMARYEpizootic haemorrhagic disease virus (EHDV) was seen by light and electron microscopy to replicate in perinuclear locations. Tubules, paracrystals and virus matrices were associated with replication sites. As infection proceeded, aggregates of virus migrated towards the cell periphery, resulting in cell membrane rupture near the virus aggregate with the subsequent release of the virus aggregates. Virus release, as seen by light microscopy, gave the appearance of occurring by a 'budding' process whereby part of the cell would swell and subsequently rupture or break away. Infectivity studies indicated that approx. 80% of newly replicated virus was released extracellularly in aggregates which required disruption to maximize infectious virus yield. Trypsin did not enhance virus infectivity. Of the six EHDV isolates used in this study each isolate was characterized by its own maximum yield obtained after several serial passages in cell culture.

Proteins of Palyam serogroup viruses

“…The growth cycles of several members of the orbivirus genus have been investigated previously and the cycle of the Palyam serogroup virus Abadina observed here is similar to that of epizootic haemorrhagic disease virus (EHDV) (Lewanczuk & Yamamoto, 1982) and the Kemerovo serogroup viruses FT363 and Mill Door/79 Spence et al, 1985). The studies show that at high multiplicity of infection viruses of the genus first produce infectious virus 5 h to 6 h p.i., the levels rise rapidly to a maximum at 12 to 13 h p.i.…”

The biochemistry of orbiviruses

“…Growth cycles for bluetongue virus type 10 (20) and epizootic haemorrhagie disease of deer virus (40) ha~/e been determined. HOWELL et al (20) followed the appearance of infectious virus in the medium overlaying the cells, and found similar results to LEWA~CZUK and YAMAMOTO (40) who examined both the cell-associated and cell-free fractions.…”

“…HOWELL et al (20) followed the appearance of infectious virus in the medium overlaying the cells, and found similar results to LEWA~CZUK and YAMAMOTO (40) who examined both the cell-associated and cell-free fractions. When material obtained from the cell and supernatant fractions during the growth cycle was sonicated, 80 per cent of the infectivity was found in the cell-free supernatant, while in unsonieated preparations 97 per cent of infectivity was associated with the cellular fractions (40). The cell-associated virus Mso followed this pattern Mthough the relative levels differed.…”

“…Replication within infected cells has been shown to occur in cytoplasmic inclusion bodies or matrices (37,38,39,40,44,45,48) which have been described as "virus factories" by Hum~A~s and ELs (27). L~CATSAS (37) showed that after cell infection with bluetongue virus, nucleoids or complete virus particles appeared within vesicles near the nucleus.…”