Biomedical subjects

K V Holmes

Publications and source records attributed to K V Holmes.

At least 37 records · Page 2Linked to original sources

PubMed1997

The murine coronavirus mouse hepatitis virus strain A59 from persistently infected murine cells exhibits an extended host range.

In murine 17 Cl 1 cells persistently infected with murine coronavirus mouse hepatitis virus strain A59 (MHV-A59), expression of the virus receptor glycoprotein MHVR was markedly reduced (S. G. Sawicki, J. H. Lu, and K. V. Holmes, J. Virol. 69:5535-5543, 1995). Virus isolated from passage 600 of the persistently infected cells made smaller plaques on 17 Cl 1 cells than did MHV-A59. Unlike the parental MHV-A59, this variant virus also infected the BHK-21 (BHK) line of hamster cells. Virus plaque purified on BHK cells (MHV/BHK) grew more slowly in murine cells than did MHV-A59, and the rate of viral RNA synthesis was lower and the development of the viral nucleocapsid (N) protein was slower than those of MHV-A59. MHV/BHK was 100-fold more resistant to neutralization with the purified soluble recombinant MHV receptor glycoprotein (sMHVR) than was MHV-A59. Pretreatment of 17 Cl 1 cells with anti-MHVR monoclonal antibody CC1 protected the cells from infection with MHV-A59 but only partially protected them from infection with MHV/BHK. Thus, although MHV/BHK could still utilize MHVR as a receptor, its interactions with the receptor were significantly different from those of MHV-A59. To determine whether a hemagglutinin esterase (HE) glycoprotein that could bind the virions to 9-O-acetylated neuraminic acid moieties on the cell surface was expressed by MHV/BHK, an in situ esterase assay was used. No expression of HE activity was detected in 17 Cl 1 cells infected with MHV/BHK, suggesting that this virus, like MHV-A59, bound to cell membranes via its S glycoprotein. MHV/BHK was able to infect cell lines from many mammalian species, including murine (17 Cl 1), hamster (BHK), feline (Fcwf), bovine (MDBK), rat (RIE), monkey (Vero), and human (L132 and HeLa) cell lines. MHV/BHK could not infect dog kidney (MDCK I) or swine testis (ST) cell lines. Thus, in persistently infected murine cell lines that express very low levels of virus receptor MHVR and which also have and may express alternative virus receptors of lesser efficiency, there is a strong selective advantage for virus with altered interactions with receptor (D. S. Chen, M. Asanaka, F. S. Chen, J. E. Shively, and M. M. C. Lai, J. Virol. 71:1688-1691, 1997; D. S. Chen, M. Asanaka, K. Yokomori, F.-I. Wang, S. B. Hwang, H.-P. Li, and M. M. C. Lai, Proc. Natl. Acad. Sci. USA 92:12095-12099, 1995; P. Nedellec, G. S. Dveksler, E. Daniels, C. Turbide, B. Chow, A. A. Basile, K. V. Holmes, and N. Beauchemin, J. Virol. 68:4525-4537, 1994). Possibly, in coronavirus-infected animals, replication of the virus in tissues that express low levels of receptor might also select viruses with altered receptor recognition and extended host range.

Animals↗

PubMed1997

Role of virus receptor-bearing endothelial cells of the blood-brain barrier in preventing the spread of mouse hepatitis virus-A59 into the central nervous system.

BALB/c mice develop a neurologic demyelinating disease after inoculation of mouse hepatitis virus (MHV), strain A59, by the intracranial, but not by the intraperitoneal route. To determine the mechanisms that prevent virus spreading through the blood-brain barrier, we analyzed expression of MHVR, a glycoprotein that serves as receptor for mouse hepatitis virus on endothelial cells of cerebral blood vessels. Our results indicated that MHVR was strongly expressed on the endoluminal pole of these cells. In addition, a direct virus binding assay showed that mouse hepatitis virus was able to bind endothelial cells via this receptor. Despite this expression of a functional viral receptor, in normal mice infected with mouse hepatitis virus by the contra-peritoneal route, no in vivo viral replication could be detected in endothelial cells from the brain, contrasting with the equivalent cells from the liver. However, shortly after i.v. administration of sodium dodecylsulfate detergent to the mice, virus infection of some cerebral endothelial cells was detected in a few mice. As a consequence of detergent treatment, virus infection was able to cross the blood-brain barrier. These results suggest that the protective role of the blood-brain barrier against spreading of mouse hepatitis virus A59 into the central nervous system is determined by a specific restriction of viral entry into the endothelial cells of cerebral origin.

Animals↗

PubMed1996

A murine and a porcine coronavirus are released from opposite surfaces of the same epithelial cells.

Epithelial cells are important target cells for coronavirus infection. Earlier we have shown that transmissible gastroenteritis coronavirus (TGEV) and mouse hepatitis coronavirus (MHV) are released from different sides of porcine and murine epithelial cells, respectively. To study the release of these viruses from the same cells, we constructed a porcine LLC-PK1 cell line stably expressing the recombinant MHV receptor cDNA (LMR cells). The MHV and TGEV receptor glycoproteins were shown by immunofluorescence to appear at the surface of the cells and to be functional so that the cells were susceptible to both MHV and TGEV infection. Both coronaviruses entered polarized LMR cells only through the apical surface. Remarkably, while the cells remained susceptible to TGEV for long periods, infectability by MHV decreased with time after plating of the cells onto filters. This was not due to a lack of expression of the MHV receptor, since this glycoprotein was still abundant on the apical surface of these cells. TGEV and MHV appeared to exit LMR cells from opposite sides. Whereas TGEV was released preferentially at the apical membrane, MHV was released preferentially at the basolateral surface. These results show that vesicles containing the two coronaviruses are targeted differently in LMR cells. We propose that the viruses are sorted at the Golgi complex into different transport vesicles that carry information directing them to one of the two surface domains. The apical release of TGEV and the basolateral release of MHV might be factors contributing to the difference in virus spread found between TGEV and MHV in their respective natural hosts, the former causing mainly a localized enteric infection, the latter spreading through the body to other organs.

Animals↗

PubMed1996

Biliary glycoprotein 1 expression during embryogenesis: correlation with events of epithelial differentiation, mesenchymal-epithelial interactions, absorption, and myogenesis.

Biliary glycoprotein (Bgp1), a carcinoembryonic antigen-related family member of the immunoglobulin superfamily, is involved in normal and neoplastic events. Analysis of Bgp1 expression throughout post-implantation mouse embryogenesis using reverse transcription-polymerase chain reactions, immunostaining with anti-Bgp1 monoclonal antibodies, and in situ hybridization with specific Bgp1 cDNA fragments revealed that Bgp1 may be involved in a number of specific embryonic processes. Immunoblot analysis of Bgp1 deletion mutant proteins indicated that distinguishable epitopes of the molecule were preferentially identified by the three Bgp1 antibodies used in this study. This distinction is supported by our immunolocalization studies during mouse embryogenesis in which the three antibodies revealed specific patterns of Bgp1 expression. Bgp1 is not expressed in early post-implantation embryos (7.5 dpc), but is found in the placenta and extra-embryonic tissues (decidual endothelial cells, giant trophoblasts, yolk sac visceral endoderm, and endometrial glands) at this time. The primitive gut epithelium and surface ectoderm were the first embryonic tissues to express Bgp1. Significant Bgp1 expression was also observed later during epithelial-mesenchymal interactions (skin, meninges, lung, kidney, salivary glands, pancreas). A unique epitope of Bgp1, detectable by the monoclonal antibody CC1, was also associated with mesenchymal expression and was prominent during myogenesis (secondary myotube formation) at sites of terminal differentiation. These studies suggest multiple roles for isoforms and glycoforms of the Bgp1 proteins localized in specific sites during prenatal development.

Animals↗

PubMed1996

Feline aminopeptidase N serves as a receptor for feline, canine, porcine, and human coronaviruses in serogroup I.

Two members of coronavirus serogroup I, human respiratory coronavirus HCV-229E and porcine transmissible gastroenteritis virus (TGEV), use aminopeptidase N (APN) as their cellular receptors. These viruses show marked species specificity in receptor utilization, as HCV-229E can utilize human but not porcine APN, while TGEV can utilize porcine but not human APN. To determine whether feline APN could serve as a receptor for two feline coronaviruses in serogroup I, feline infectious peritonitis virus (FIPV) and feline enteric coronavirus (FeCV), we cloned the cDNA encoding feline APN (fAPN) by PCR from cDNA isolated from a feline cell line and stably expressed it in FIPV- and FeCV-resistant mouse and hamster cells. The predicted amino acid sequence of fAPN shows 78 and 77% identity with human and porcine APN, respectively. When inoculated with either of two biologically different strains of FIPV or with FeCV, fAPN-transfected mouse and hamster cells became infected and viral antigens developed in the cytoplasm. Infectious FIPV was released from hamster cells stably transfected with fAPN. The fAPN-transfected mouse and hamster cells were challenged with other coronaviruses in serogroup I including canine coronavirus, porcine coronavirus TGEV, and human coronavirus HCV-229E. In addition to serving as a receptor for the feline coronaviruses, fAPN also served as a functional receptor for each of these serogroup I coronaviruses as shown by development of viral antigens in the cytoplasm of infected mouse or hamster cells stably transfected with fAPN. In contrast, fAPN did not serve as a functional receptor for mouse hepatitis virus (MHV-A59), which is in serogroup II and utilizes mouse biliary glycoprotein receptors unrelated to APN. Thus, fAPN serves as a receptor for a much broader range of group I coronaviruses than human and porcine APNs. The human, porcine, and canine coronaviruses in serogroup I that are able to use fAPN as a receptor have previously been shown to infect cats without causing disease. Therefore, host factors in addition to receptor specificity apparently affect the virulence and transmissibility of nonfeline serogroup I coronaviruses in the cat.

3T3 Cells↗

PubMed1996

Expression of the recombinant anchorless N-terminal domain of mouse hepatitis virus (MHV) receptor makes hamster of human cells susceptible to MHV infection.

Mouse hepatitis virus (MHV) receptor, the receptor for the murine coronavirus MHV, was expressed in MHV-resistant hamster and human cells as a series of mutant, recombinant glycoproteins with carboxy-terminal deletions lacking the cytoplasmic tail, transmembrane domain, and various amounts of the immunoglobulin constant-region-like domains. The soluble receptor glycoproteins containing the N-terminal virus-binding domain were released into the supernatant medium and inactivated the infectivity of MHV-A59 virions in a concentration-dependent manner. Surprisingly, some of the anchorless glycoproteins were found on the plasma membranes of transfected cells by flow cytometry, and these cells were rendered susceptible to infection with three strains of MHV. Thus, in the cells in which the anchorless, recombinant receptor glycoprotein is synthesized, some of the protein is bound to an unidentified moiety on the plasma membrane, which allows it to serve as a functional virus receptor.

Amino Acid Sequence↗

PubMed1996

Attachment glycoproteins and receptor specificity of rat coronaviruses.

Murine coronavirus (MHV) and rat coronavirus (RCV) are antigenically related viruses that have different natural rodent hosts. Both MHV and RCV can be propagated in the L2(Percy) and CMT-93 mouse cell lines. In these cell lines MHV uses the MHV receptor (MHVR or Bgp1a) and several related murine Bgp glycoproteins in the immunoglobulin superfamily as receptors. To determine whether RCV also uses these murine glycoproteins as receptors, we characterized the envelope glycoproteins of two strains of RCV and compared the effects of anti-MHVR monoclonal antibody on susceptibility of the mouse cells to MHV and RCV. The Parker (RCV-P) and sialodacryoadenitis (RCV-SDAV) strains of RCV expressed the spike glycoprotein S, but only RCV-P expressed a hemagglutinin-esterase glycoprotein that had acetylesterase activity. Therefore RCV-SDAV must bind to cellular receptors by the viral S glycoprotein, whereas RCV-P might bind to cells by its hemagglutinin-esterase glycoprotein as well as by S. Pretreatment of L2(Percy) 41.a or CMT-93 cells with anti-MHVR monoclonal antibody blocked infection with MHV-A59 but did not prevent infection of these murine cells with RCV-P or RCV-SDAV. Baby hamster kidney cells transfected with cDNAs encoding MHVR (Bgp1a) or Bgp2 were susceptible to MHV-A59 but not to RCV-P or RCV-SDAV. Thus the RCV strains cannot use these murine coronavirus receptors and must be infecting murine cells by another, as yet unknown, receptor.

Animals↗

PubMed1995

Intracellular localization of polypeptides encoded in mouse hepatitis virus open reading frame 1A.

We have investigated the intracellular localization of several of the proteolytic cleavage products derived from the 5' portion of mouse hepatitis virus (MHV) gene 1. Antisera UP1 recognizes the N-terminal ORF1a cleavage product p28. Immunofluorescent staining of cells with this antisera resulted in a diffuse punctate pattern of cytoplasmic staining, indicating that this protein is widely distributed in the cytoplasm. Immunofluorescent staining of infected cells with antisera which recognize polypeptides p240 and p290 stained discrete vesicular perinuclear structures suggesting that these proteins localized to the Golgi. This was confirmed by double immunofluorescent staining of BHK cells expressing the MHV receptor (BHK-R) with a Golgi specific antibody in addition to our anti-MHV ORF1a antibodies. Antisera UP102 recognizes p28 and the immediately downstream p65 gene product. Double immunofluorescent staining of MHV infected BHK-R cells with UP102 labeled discrete vesicular structures overlapping the Golgi complex. In addition there was punctate staining more widely distributed in the cytoplasm. The simplest explanation for this pattern is that p65 is also localized to the Golgi region of the cell, whereas p28 is more widespread. Plasmids containing the first 4.7 and 6.75 kb of ORF 1a have been expressed using the coupled vaccinia virus-T7 polymerase system. Images obtained by immunofluorescent staining of transfectants with our anti-ORF1a antisera are similar to those obtained during infection with A59. These studies indicate that the signals which direct p290 to the Golgi are likely contained between the C-terminus of p28 and ORF1a residue 1494.

Animals↗

PubMed1995

Multiple receptor-dependent steps determine the species specificity of HCV-229E infection.

Human coronavirus (HCV)-229E causes disease only in humans and grows in human cells and in cells of other species that express recombinant human aminopeptidase N (hAPN), the receptor for HCV-229E. We compared the species specificity of HCV-229E infection with the species specificity of virus binding using immunofluorescence, assay of virus yields, fluorescence activated cell sorting and a monoclonal antibody directed against hAPN that blocks infection. We found that HCV-229E binds to intestinal brush border membranes (BBM) and to membranes of cell lines from cats, dogs, pigs, and humans, however the virus only infects two of these species. HCV-229E will not bind to BBM or to membranes from cell lines derived from hamster or mice. Animal coronaviruses related to HCV-229E, including FIPV, CCV, and TGEV bind to cell membranes from cats, dogs, cows, pigs and humans (but not mice), while each virus infects cells from only a subset of these species. Infectious genomic HCV-229E RNA, can infect cells of all of these species. These data suggest that the species-specificity of infection for this serogroup of coronaviruses is determined at the levels of virus binding and penetration. Since binding of viral spike glycoprotein to cellular receptors is not the only limiting factor, we suggest that one or more steps associated with virus penetration may determine the species specificity of infection with the HCV-229E serogroup of coronaviruses.

Animals↗

PubMed1995

Characterization of a new gene that encodes a functional MHV receptor and progress in the identification of the virus-binding site(s).

Several splice variants of the murine biliary glycoprotein 1 (Bgp 1) gene in the carcinoembryonic antigen gene superfamily serve as cellular receptors for mouse hepatitis virus. RNAPCR and immunoblot analysis of the receptor in inbred mouse strains showed that the glycoproteins expressed in SJL/J mice are encoded by an allelic variant of the Bgp 1 gene, named Bgp 1b. We recently cloned and characterized a second gene, Bgp 2, that encodes a functional MHV receptor glycoprotein which is not recognized by anti-MHVR MAb-CC1. A third gene related to Bgp 1 was cloned and expressed and shown to encode a soluble protein called Cea-10 that differs significantly in its N-terminal domain from Bgp 1 and Bgp 2. Chimeric proteins constructed between the different murine Bgps and point mutations in the prototype MHV receptor, Bgp 1a or MHVR, were analyzed to further characterize the MAb-CC1-binding and virus-binding domains within the N terminal domain of the receptor. Thus, the murine host for MHV expresses multiple splice variants of mRNAs encoded by several different Bgp-related genes which differ in their ability to serve as MHV receptors. The differential expression of these genes in different murine tissues may help to explain the tissue tropism of MHV strains.

Alternative Splicing↗

PubMed1995

Mouse hepatitis virus receptor activities of an MHVR/mph chimera and MHVR mutants lacking N-linked glycosylation of the N-terminal domain.

Mouse hepatitis virus binds to the N-terminal domain of its receptor, MHVR, a murine biliary glycoprotein with four immunoglobulin-like domains (G.S. Dveksler, M. N. Pensiero, C. W. Dieffenbach, C. B. Cardellichio, A.A. Basile, P.E. Elia, and K. V. Holmes, Proc. Natl. Acad. Sci. USA 90:1716-1720, 1993). A recombinant protein with only the anchored N-terminal domain was not a functional receptor, but a recombinant protein with the N-terminal domain of MHVR linked to the second and third immunoglobulin-like domains and anchor from the mouse poliovirus receptor homolog, mph, was a functional receptor for mouse hepatitis virus. The native four-domain MHVR has 16 potential N-linked glycosylation sites, including three on the N-terminal domain. Recombinant proteins lacking each one of these three sites or all three of them were functional receptors. Thus, glycosylation of the N-terminal domain is not required, but a glycoprotein longer than the N-terminal domain is required for virus receptor activity.

Animals↗

PubMed1995

Thymus involution induced by mouse hepatitis virus A59 in BALB/c mice.

Mouse hepatitis virus A59 (MHV-A59) infection of adult BALB/c mice induced a severe, transient atrophy of the thymus. The effect was maximal at 1 week after infection, and thymuses returned to normal size by 2 weeks after infection. There was no effect of glucocorticoids, since thymus atrophy was also found in adrenalectomized, infected mice. In infected thymus, immature CD4+ CD8+ lymphocytes were selectively depleted, and apoptosis of lymphocytes was increased. The MHV receptor glycoprotein MHVR was detected on thymus epithelial cells but not on T lymphocytes. In a small number of stromal epithelial cells, but in very few lymphocytes, the viral genome was detectable by in situ hybridization. These observations suggested that MHV-A59-induced thymic atrophy results not from a generalized lytic infection of T lymphocytes but rather from apoptosis of immature double-positive T cells that might be caused by infection of a small proportion of thymus epithelial cells or from inappropriate secretion of some factor, such as a cytokine.

Adrenalectomy↗

PubMed1995

Interaction of mouse hepatitis virus (MHV) spike glycoprotein with receptor glycoprotein MHVR is required for infection with an MHV strain that expresses the hemagglutinin-esterase glycoprotein.

In addition to the spike (S) glycoprotein that binds to carcinoembryonic antigen-related receptors on the host cell membrane, some strains of mouse coronavirus (mouse hepatitis virus [MHV]) express a hemagglutinin esterase (HE) glycoprotein with hemagglutinating and acetylesterase activity. Virions of strains that do not express HE, such as MHV-A59, can infect mouse fibroblasts in vitro, showing that the HE glycoprotein is not required for infection of these cells. The present work was done to study whether interaction of the HE glycoprotein with carbohydrate moieties could lead to virus entry and infection in the absence of interaction of the S glycoprotein with its receptor glycoprotein, MHVR. The DVIM strain of MHV expresses large amounts of HE glycoprotein, as shown by hemadsorption, acetylesterase activity, and immunoreactivity with antibodies directed against the HE glycoprotein of bovine coronavirus. A monoclonal anti-MHVR antibody, MAb-CC1, blocks binding of virus S glycoprotein to MHVR and blocks infection of MHV strains that do not express HE. MAb-CC1 also prevented MHV-DVIM infection of mouse DBT cells and primary mouse glial cell cultures. Although MDCK-I cells express O-acetylated sialic acid residues on their plasma membranes, these canine cells were resistant to infection with MHV-A59 and MHV-DVIM. Transfection of MDCK-I cells with MHVR cDNA made them susceptible to infection with MHV-A59 and MHV-DVIM. Thus, the HE glycoprotein of an MHV strain did not lead to infection of cultured murine neural cells or of nonmurine cells that express the carbohydrate ligand of the HE glycoprotein. Therefore, interaction of the spike glycoprotein of MHV with its carcinoembryonic antigen-related receptor glycoprotein is required for infectivity of MHV strains whether or not they express the HE glycoprotein.

Animals↗

PubMed1995

Persistent infection of cultured cells with mouse hepatitis virus (MHV) results from the epigenetic expression of the MHV receptor.

The A59 strain of murine coronavirus mouse hepatitis virus (MHV) can cause persistent infection of 17C1-1 cells and other murine cell lines. Persistently infected cultures released large amounts of virus (10(7) to 10(8) PFU/ml) and were resistant to superinfection with MHV but not to infection with unrelated Semliki Forest and vesicular stomatitis viruses. The culture medium from persistently infected cultures did not contain a soluble inhibitor such as interferon that protected uninfected cells from infection by MHV or vesicular stomatitis virus. The persistent infection was cured if fewer than 100 cells were transferred during subculturing, and such cured cultures were susceptible to reinfection and the reestablishment of persistent infection. Cultures of 17C1-1 cells that had been newly cloned from single cells consisted of a mixture of MHV-resistant and -susceptible cells. 17C1-1/#97 cells, which were cured by subcloning after 97 passages of a persistently infected culture over a 1-year period, contained 5 to 10% of their population as susceptible cells, while 17C1-1/#402 cells, which were cured by subcloning after 402 passages over a 3-year period, had less than 1% susceptible cells. Susceptibility to infection correlated with the expression of MHV receptor glycoprotein (MHVR [Bgp1a]). Fluorescence-activated cell sorter analysis with antibody to MHVR showed that 17C1-1/#97 cells contained a small fraction of MHVR-expressing cells. These MHVR-expressing cells were selectively eliminated within 24 h after challenge with MHV-A59, and pretreatment of 17C1-1/#97 cells with monoclonal antibody CC1, which binds to the N-terminal domain of MHVR, blocked infection. We conclude that the subpopulation of MHVR-expressing cells were infected and killed in acutely or persistently infected cultures, while the subpopulation of MHVR-nonexpressing cells survived and proliferated. The subpopulation of MHVR-negative cells produced a small proportion of progeny cells that expressed MHVR and became infected, thereby maintaining the persistent infection as a steady-state carrier culture. Thus, in 17C1-1 cell cultures, the unstable or epigenetic expression of MHVR permitted the establishment of a persistent, chronic infection.

3T3 Cells↗

PubMed1995

Tissue and cellular distribution of an adhesion molecule in the carcinoembryonic antigen family that serves as a receptor for mouse hepatitis virus.

BACKGROUND: The receptor for the murine coronavirus mouse hepatitis virus (MHV)-A59, called MHVR or Bgp1a, is a glycoprotein in the carcinoembryonic antigen family of the Ig superfamily. Biliary glycoprotein (Bgp) isoforms play a role in cell adhesion, bile acid transport, and ecto-ATPase activity. MHV-resistant SJL/J mice express a different allele of Bgp1 called Bgp1b. Analysis of the tissue and cellular distribution of Bgp1 proteins can therefore provide new insight on both cellular functions and MHV-A59--induced pathogenesis. EXPERIMENTAL DESIGN: Bgp1 expression was analyzed in the digestive, respiratory, endocrine, urinary, and central nervous systems of adult BALB/c and SJL/J mice by immunocytochemistry and immunoelectron microscopy using a monoclonal Ab specific for the N-terminal domain of the Bgp1a proteins and polyclonal rabbit anti-Bgp1, which recognizes both the Bgp1a and Bgp1b proteins. The function of Bgp1 proteins as viral receptors was tested on tissue sections by a virus binding assay. MHV-A59 replication was analyzed by immunocytochemistry. RESULTS: Bgp1 expression was observed on membranes of epithelial cells (including hepatocytes, intestinal, endocrine, and respiratory epithelial cells), kidney proximal tubules, and endothelial cells in many tissues. It was usually localized at the apical pole of the cells and, when present, on the brush borders and the cilia. A new direct virus binding assay showed that MHV attachment onto cells correlates with Bgp1 expression. Viral infection was detected in hepatocytes, lymphoid tissue, and the exocrine pancreas but not in endocrine cells, enterocytes, kidney, or respiratory cells. In the central nervous system, no immunolabeling of neurons or glial cells was found with anti-Bgp1 Ab. CONCLUSIONS: Bgp1 proteins are present on BALB/c and SJL/J epithelia and endothelia. These glycoproteins might be involved in cell-to-cell contacts, for example between hepatocytes. On BALB/c mice, Bgp1a expression is consistent with the tropism of MHV-A59 for the liver. However, Bgp1a was also expressed on cells that were not infected by MHV-A59.

Animals↗

PubMed1995

Pathology and immunohistochemistry of callitrichid hepatitis, an emerging disease of captive New World primates caused by lymphocytic choriomeningitis virus.

Callitrichid hepatitis is an arenavirus infection that recently emerged as a highly fatal disease of New World primates in the Callitrichidae family. As we previously reported, these primates develop hepatitis after contact with mice that are infected with variants of LCMV (LVMCCH), recently determined to have 86% identity with GC-P gene of the Armstrong and Western strains of LCMV. Here, we describe the histopathological lesions and tissue localization of viral antigens in confirmed cases of callitrichid hepatitis from recent outbreaks in two U.S. zoos. The liver in marmosets and tamarins with fatal infections consistently showed degeneration, necrosis, and inflammation, with variable involvement of the spleen, lymph nodes, adrenal glands, intestine, pancreas, and central nervous system. Lymphocytic choriomeningitis virus antigens were identified immunohistochemically in necrotic foci in these organs as well as in nondegenerating areas in lungs, kidney, urinary bladder, brain, and testes. The multi-organ tropism and histological pattern of LCMV infection in marmosets and tamarins are similar to those reported for the highly virulent arenavirus that causes Lassa fever in humans. Comparative studies of callitrichid hepatitis and Lassa fever would therefore be mutually beneficial for human and nonhuman primate medicine.

Animals↗

PubMed1994

B lymphocyte and macrophage expression of carcinoembryonic antigen-related adhesion molecules that serve as receptors for murine coronavirus.

The expression of carcinoembryonic antigen (CEA)-related glycoproteins that have been associated with intercellular adhesion and that serve as receptors for mouse hepatitis virus (MHV) was analyzed in cells from the immune system of BALB/c mice using immunolabeling and RNA polymerase chain reaction amplification of receptor transcripts. These glycoproteins, which are called biliary glycoproteins, were highly expressed in B lymphocytes, including cells of the B-1a (CD5+) lineage, and in macrophages, but were not detectable in resting T lymphocytes. Similarly, murine cell lines of B cell and macrophage origin expressed messenger RNA encoding CEA-related molecules, while the corresponding mRNA was only slightly detectable in a T cell line. These CEA-related cell adhesion glycoproteins were also expressed in endothelial cells. Therefore, their specific interaction with their so far unknown ligand may be of functional importance in cellular interactions in the immune response. Monoclonal antibody directed against these glycoproteins blocked MHV-A59 infection of the B cell-derived SP20 cell line. Thus, the functional receptors for MHV on B lymphocytes, like those on murine fibroblasts, are isoforms of CEA-related glycoproteins. Treatment of B cells with anti-receptor antibody also blocked B cell-mediated cytotoxicity against MHV-A59-infected fibroblasts, indicating that this phenomenon is mediated by interaction of viral attachment protein on the infected target cells with specific CEA-related receptor glycoproteins on the effector B cells.

Animals↗

PubMed1994

Bgp2, a new member of the carcinoembryonic antigen-related gene family, encodes an alternative receptor for mouse hepatitis viruses.

Murine coronaviruses such as mouse hepatitis virus (MHV) infect mouse cells via cellular receptors that are isoforms of biliary glycoprotein (Bgp) of the carcinoembryonic antigen gene family (G. S. Dveksler, C. W. Dieffenbach, C. B. Cardellichio, K. McCuaig, M. N. Pensiero, G.-S. Jiang, N. Beauchemin, and K. V. Holmes, J. Virol. 67:1-8, 1993). The Bgp isoforms are generated through alternative splicing of the mouse Bgp1 gene that has two allelic forms called MHVR (or mmCGM1), expressed in MHV-susceptible mouse strains, and mmCGM2, expressed in SJL/J mice, which are resistant to MHV. We here report the cloning and characterization of a new Bgp-related gene designated Bgp2. The Bgp2 cDNA allowed the prediction of a 271-amino-acid glycoprotein with two immunoglobulin domains, a transmembrane, and a putative cytoplasmic tail. There is considerable divergence in the amino acid sequences of the N-terminal domains of the proteins coded by the Bgp1 gene from that of the Bgp2-encoded protein. RNase protection assays and RNA PCR showed that Bgp2 was expressed in BALB/c kidney, colon, and brain tissue, in SJL/J colon and liver tissue, in BALB/c and CD1 spleen tissue, in C3H macrophages, and in mouse rectal carcinoma CMT-93 cells. When Bgp2-transfected hamster cells were challenged with MHV-A59, MHV-JHM, or MHV-3, the Bgp2-encoded protein served as a functional MHV receptor, although with a lower efficiency than that of the MHVR glycoprotein. The Bgp2-mediated virus infection could not be inhibited by monoclonal antibody CC1 that is specific for the N-terminal domain of MHVR. Although CMT-93 cells express both MHVR and Bgp2, infection with the three strains of MHV was blocked by pretreatment with monoclonal antibody CC1, suggesting that MHVR was the only functional receptor in these cells. Thus, a novel murine Bgp gene has been identified that can be coexpressed in inbred mice with the Bgp1 glycoproteins and that can serve as a receptor for MHV strains when expressed in transfected hamster cells.

Amino Acid Sequence↗