Effects of avian viruses on cultured chicken bone‐marrow‐derived macrophages

Abstract

Cultured chicken bone-marrow-derived macrophages have been assayed for their susceptibility to infection with various avian viruses. Three criteria of infection were employed: (1) Virus-induced alterations in cell morphology ; (2) presence of intracellular viral antigens detectable by immunofluorescence; (3) kinetics of virus release by infected macrophages. Macrophages proved to be resistant to Marek's disease virus (MDV), herpesvirus of turkeys (HVT-FC126), infectious bronchitis virus (IBV) and reticuloendotheliosis virus (REV). MDV included the pathogenic HPRS-16 strain prepared from feather follicles, and the apathogenic HPRS-24 strain adapted to growth in chick embryo fibroblast cultures. IBV included both embryo-propagated and tissue culture-adapted variants of the apathogenic Beaudette strain and a pathogenic Massachusetts-type strain. REV comprised the strains REV-C, CSV and oncogenic virus of the REV-F strain. Adenovirus, infectious laryngotracheitis (ILT) virus, reovirus, infectious bursal disease virus (IBDV) and Newcastle disease virus (NDV) replicated in macrophages causing different but characteristic cytopathic effects, or alterations in cell morphology associated with macrophage activation. The most prominent effect of IBDV and lentogenic NDV infection were morphological signs of macrophage activation, i.e. enlargement or 'transformation' of cells which tended to survive in infected cultures and were usually free of detectable amounts of immunofluorescent viral antigens. Macrophage cultures were less susceptible to infection with adenovirus (OTE strain), pathogenic ILT virus and lentogenic NDV (B1 strain) than permissive chicken kidney cell (CKC) cultures. In contrast, macrophage cultures were significantly more susceptible to infection with reovirus than CKC cultures, indicating that bone-marrow-derived macrophages might be the major target cells of this virus species. Virus restriction by cultured bone-marrow-derived macrophages was expressed to various degrees among the different avian virus species and among different strains of the same virus species, however, it was not generally correlated with the pathogenicity of these viruses in chickens.

Activating effects of interferons, lymphokines and viruses on cultured chicken macrophages1

“…The experimental data summarised in Table 3 confirm that the infectivity of avian reovirus was about 10-fold higher if assayed in macrophage cultures (MAD) than in CKC cultures (PFU), as reported earlier (Bülow and Klasen, 1983b). The minimum macrophage activating dose (MAD) of UV-inactivated reovirus was only 10-to 30-fold smaller than the infectivity before inactivation (samples 2 and 3, Table 3).…”

“…Morphological change of cultured macrophages resembling those induced by lymphokines can also be induced by viruses. Infectious bursal disease virus (IBDV) caused persistent signs of activation whereas reovirus caused a transient enhancement of macrophage spreading, rapidly followed by cellular degeneration, and its infectivity was about 10-fold higher for macrophages than for chicken kidney cells (Bülow and Klasen, 1983b). It was the purpose of the present study to examine dose-dependent effects of different lymphokine preparations, interferons, and live or inactivated reovirus and IBDV, on cultured chicken macrophages and their possible mechanisms.…”

“…lymphokines and interferons (Rabinovitch and Hamburg, 1980). There is circumstantial evidence that the latter mechanism is effective in chickens infected with Marek's disease virus (Kodama et al, 1979;Lee et al, 1978;Powell, 1983) because Marek's disease virus is unable to infect chicken macrophages or to induce changes in their morphology and functions (Bülow and Klasen, 1983b;. Investigation of direct effects of viruses on macrophages can therefore only be made with cells isolated by in vitro cultivation.…”

“…Investigation of direct effects of viruses on macrophages can therefore only be made with cells isolated by in vitro cultivation. To our knowledge, however, all research on the effects of viruses on cultured avian or mammalian macrophages, reviewed previously (Bülow and Klasen, 1983b), has been focussed on virus replication or virus restriction, and on oncogenic transformation by tumour viruses. There have been no reports as yet on virus-induced macrophage activation in vitro.…”

Pathology and Virus Tissue Distribution of Turkey Origin Reoviruses in Experimentally Infected Turkey Poults

“…45,52 Virus staining was present in macrophages in the bursa and spleen, indicating that macrophages are also a target cell in turkeys. However, in the early stages of the infection the viruses were primarily found in epithelial cells of the intestine and the bursa.…”