Goat Milk Epithelial Cells Are Highly Permissive to CAEV Infection in Vitro

Abstract

The main route of small ruminant lentivirus dissemination is the ingestion of infected cells present in colostrum and milk from infected animals. However, whether only macrophages or other cell subtypes are involved in this transmission is unknown. We derived epithelial cell cultures, 100% cytokeratin positive, from milk of naturally infected and noninfected goats. One such culture, derived from a naturally infected goat, constitutively produced a high titer of virus in the absence of any cytopathic effect. The other cultures, negative for natural lentivirus infection, were tested for their susceptibility to infection with the CAEV-CO strain and a French field isolate CAEV-3112. We showed that milk epithelial cells are easily infected by either virus and produce viruses at titers as high as those obtained in permissive goat synovial membrane cells. The CAEV-CO strain replicated in milk epithelial cells in absence of any cytopathic effect, whereas the CAEV-3112 field isolate induced both cell fusion and cell lysis. Our results suggest that CAEV-infected milk epithelial cells of small ruminants may play an important role in virus transmission and pathogenesis.

Maedi-visna virus infection of ovine mammary epithelial cells

“…MVV can replicate in vitro in a wide variety of ovine cells [30], because the restriction that the virus presents under natural conditions is no longer maintained in vitro [29]. Similarly, CAEV, the caprine counterpart of MVV, can replicate in a variety of cells in vitro [14,15,20,27,28,37] and, significantly, HIV-1 can also productively infect different cell lines in vitro including human OMEC [43].…”

“…It has been assumed that tissue macrophages are the only target cells for MVV, but several studies have demonstrated that MVV can infect a broader cell range such as oligodendrocytes, astrocytes, fibroblasts [10], endothelial cells [6] and smooth muscle cells [21], among others. It is known that the epithelial cells from granulosa, goat oviduct and those present in goat milk are highly permissive in vitro to the caprine arthritis and encephalitis virus (CAEV) [14,15,27,28]. Even early embryonic cells from in vivo-produced goat embryos transmit this virus [16].…”

Immortalized goat milk epithelial cell lines replicate CAEV at high level

“…In contrast however, our results differ from those reported for HIV-1 replication in epithelial cells in at least two major points. First, all our TIGMEC lines and all primary cultures of GMEC we tested [24] are easily infected by CAEV, whereas four of eleven human primary epithelial cells and one of three cell lines were found resistant to HIV-1 infection [31]. These results may be explained by an inefficient usage of galactosyl-ceramide rather than the CD4 receptor by HIV-1 to enter these cells [15].…”

“…CAEV mastitis presents a hardening of the udder during lactation period with diminution of milk production, and involves an important interstitial infiltration and accumulation of lymphocytes. Lymphocytes are not susceptible to infection by CAEV, which has been shown to target cells of the monocytemacrophage lineage, but we have recently shown that primary mammary epithelial cells readily support CAEV infection and may be involved in the pathogenesis of mastitis [24].…”

“…The initial culture monolayers contained mainly monocyte/macrophage cell types that differentiated into mature macrophages, as identified by morphological changes (enlargement of cells) and very strong adhesion. After 2 to 3 weeks in culture, foci of epithelial cells, morphologically clearly distinguishable from macrophages, emerged and, after two serial passages, homogenous epithelial cell culture monolayers were obtained [24].…”