Lactogenic immunity following vaccination of cattle with bovine coronavirus

Vaccine
Volume 19, Issues 2–3, 15 September 2000, Pages 189-196

C.F Crouch, S Oliver, D.C Hearle, A Buckley, A.J Chapman, M.J Francis

Abstract

In order to investigate the ability of an oil adjuvanted vaccine containing bovine coronavirus antigen to enhance lactogenic immunity in the calf, pregnant cows and heifers were vaccinated and specific virus neutralising antibody levels determined in serum, colostrum and milk. Pre-existing antibody titres (as a result of natural infection) in the serum of these animals were found to be significantly increased as a result of a single shot vaccination carried out between 2 and 12 weeks before calving. This was reflected in a similar increase in the titre and duration of specific antibody in milk and colostrum that was passed on to the calves. The overall response observed was highly dependent on an adequate antigen payload being incorporated within the single dose vaccine. No abnormal local or systemic reactions were observed as a result of vaccination. It is hoped that this approach will lead to the production of a superior commercial vaccine for the protection of neonatal calves against enteric coronavirus infection.

Keywords

Bovine coronavirus, Cattle, Lactogenic immunity

Downstream Ribosomal Entry for Translation of Coronavirus TGEV Gene 3b

Virology
Volume 269, Issue 1, 30 March 2000, Pages 172-182

Jennifer Black O'Connor, David A.Brian

Abstract

Gene 3b (ORF 3b) in porcine transmissible gastroenteritis coronavirus (TGEV) encodes a putative nonstructural polypeptide of 27.7 kDa with unknown function that during translation in vitro is capable of becoming a glycosylated integral membrane protein of 31 kDa. In the virulent Miller strain of TGEV, ORF 3b is 5′-terminal on mRNA 3–1 and is presumably translated following 5′ cap-dependent ribosomal entry. For three other strains of TGEV, the virulent British FS772/70 and Taiwanese TFI and avirulent Purdue-116, mRNA species 3–1 is not made and ORF 3b is present as a non-overlapping second ORF on mRNA 3. ORF 3b begins at base 432 on mRNA 3 in Purdue strain. In vitro expression of ORF 3b from Purdue mRNA 3-like transcripts did not fully conform to a predicted leaky scanning pattern, suggesting ribosomes might also be entering internally. With mRNA 3-like transcripts modified to carry large ORFs upstream of ORF 3a, it was demonstrated that ribosomes can reach ORF 3b by entering at a distant downstream site in a manner resembling ribosomal shunting. Deletion analysis failed to identify a postulated internal ribosomal entry structure (IRES) within ORF 3a. The results indicate that an internal entry mechanism, possibly in conjunction with leaky scanning, is used for the expression of ORF 3b from TGEV mRNA 3. One possible consequence of this feature is that ORF 3b might also be expressed from mRNAs 1 and 2.

Keywords

porcine transmissible gastroenteritis coronavirus, gene 3b, ribosomal scanning, ribosomal shunting

Capture ELISA systems for the detection of bovine coronavirus-specific IgA and IgM antibodies in milk and serum

Veterinary Microbiology
Volume 72, Issues 3–4, 15 March 2000, Pages 183-206

K. Naslund, M. Traven, B. Larsson, A. Silvan, N. Linde

Abstract

Isotype-capture ELISAs for BCV-specific IgA and IgM were developed and tested on milk and serum samples from Swedish cattle. The capture ELISAs showed higher sensitivity than indirect ELISAs for detection of BCV-specific IgA and IgM. In the capture ELISAs the agreement between detection in milk and serum samples was 94% for IgA and 86% for IgM. The correlation between log10 titres in milk and serum was r=0.82 (P<0.001) for IgA and 0.84 (P<0.001) for IgM. Milk seemed a better target than serum for diagnosing specific IgA at low levels. There was no variation in the isotype-specific BCV antibody titres between healthy quarters of the same udder, but subclinical mastitis was associated with higher levels of IgA antibodies and weak false IgM positive reactions in undiluted milk. Bovine IgA and IgM antibodies in milk and serum showed high stability towards freezing and thawing and storage at room temperature.

The antibody responses to BCV were followed in milk and serum from six dairy cows and in serum from four calves for a period of 1 year after an outbreak of winter dysentery (WD). In this outbreak some animals became reinfected with BCV. The IgA and IgM capture ELISAs differentiated between primarily BCV infected and reinfected animals. In the primarily infected cattle, IgM antibodies were first detected in milk and serum four to nine days after the first WD symptoms observed, and were subsequently detected for at least 2–3 weeks. IgM was also detected in the reinfected cows, but mostly at lower levels and for a shorter period of time than in the primarily infected animals. In milk, however, the IgM response of the reinfected cows was detected for a longer period of time than in serum. Six months after the outbreak, IgA was still detected in both serum and milk of all six cows and also in serum of one calf. The reinfected cows showed higher and more long-lasting peak levels of IgA in milk and serum than the primarily infected cows, indicating boosting of the IgA response.

Keywords

Cattle, IgA, IgM, Isotype-capture, Bovine coronavirus, Milk, Reinfection

Unique N-linked glycosylation of murine coronavirus MHV-2 membrane protein at the conserved O-linked glycosylation site

Virus Research
Volume 66, Issue 2, February 2000, Pages 149-154

Yasuko K. Yamada, Mikiko Yabe, Takahiro Ohtsuki, Fumihiro Taguchi

Abstract

The membrane (M) proteins of murine coronavirus (MHV) strains have been reported to contain only O-linked oligosaccharides. The predicted O-glycosylation site consisting of four amino acid residues of Ser–Ser–Thr–Thr is located immediately adjacent to the initiator Met and is well conserved among MHV strains investigated so far. We analyzed the nucleotide sequence of a highly virulent strain MHV-2 M-coding region and demonstrated that MHV-2 had a unique amino acid, Asn, at position 2 at the conserved O-glycosylation site. We also demonstrated that this substitution added N-linked glycans to MHV-2 M protein resulting in increment of molecular mass of MHV-2 M protein compared with JHM strain having only O-linked glycans.

Keywords

Murine coronavirus, MHV, M protein, N-glycosylation, O-glycosylation

Development of a nested PCR assay for the detection of canine coronavirus

Journal of Virological Methods
Volume 80, Issue 1, June 1999, Pages 11-15

A Pratelli, M Tempesta, G Greco, V Martella, C Buonavoglia

Abstract

A diagnostic test for canine coronavirus (CCV) infection based on a nested polymerase chain reaction (n-PCR) assay was developed and tested using the following coronavirus strains: CCV (USDA strain), CCV (45/93, field strain), feline infectious peritonitis virus (FIPV, field strain), trasmissible gastroenteritis virus (TGEV, Purdue strain), bovine coronavirus (BCV, 9WBL-77 strain), infectious bronchitis virus (IBV, M-41 strain) and fecal samples of dogs with CCV enteritis. A 230-bp segment of the gene encoding for transmembrane protein M of CCV is the target sequence of the primer. The test described in the present study was able to amplify both CCV and TGEV strains and also gave positive results on fecal samples from CCV infected dogs. n-PCR has a sensitivity as high as isolation on cell cultures, and can therefore be used for the diagnosis of CCV infection in dogs.

Keywords

Canine coronavirus, Dogs, Nested-polymerase chain reaction

Activity of a purified His-tagged 3C-like proteinase from the coronavirus infectious bronchitis virus

Virus Research
Volume 60, Issue 2, April 1999, Pages 137-145

K.W Tibbles, D Cavanagh, T.D.K Brown

Abstract

Previous studies in vitro of the processing of cloned polyprotein fragments from the coronavirus infectious bronchitis virus (IBV) large open reading frame (ORF1), confirmed the activity of a predicted 3C-like proteinase (3CLP) domain and suggested that the proteinase is released autocatalytically from the polyprotein in the form of a 35 kDa protein, 3CLpro, capable of further cleavages in trans. In order to identify such cleavages within the ORF1 polyprotein mediated by 3CLpro, the proteinase was expressed in bacteria, purified and used in trans cleavage assays with polyprotein fragments lacking the 3CLP domain as targets. The proteinase was expressed as a polyprotein fragment which was able to process during expression in bacterial cells, releasing mature 3CLpro. A histidine (His6) tag was introduced close to the C-terminus of the proteinase to aid purification. Processing demonstrated by the tagged proteinase was indistinguishable from that of the wild-type enzyme indicating that the site chosen for the tag was permissive. From these studies we were able to demonstrate trans cleavages consistent with the use of most of the previously predicted or identified sites within the open reading frame of gene 1. This tentatively completes the processing map for the ORF1 region with respect to 3CLpro.

Keywords

Coronavirus, 3CLproteinase, His-tagged, Bacterial expression, Trans processing

ECG changes after rabbit coronavirus infection

Journal of Electrocardiology
Volume 32, Issue 1, January 1999, Pages 21-32

Lorraine K.Alexander DRPH, Bruce W.Keene DVM, Boyd L.Yount BS, Joachim Dieter Geratz MD, J.David Small DVM, MPH, Ralph S.Baric PhD

Abstract

This study examines the electrocardiographic (ECG) changes following rabbit coronavirus (RbCV) infection. We have shown that infection with RbCV results in the development of myocarditis and congestive heart failure and that some survivors of RbCV infection go on to develop dilated cardiomyopathy in the chronic phase. Serial ECGs were recorded on 31 RbCV-infected rabbits. Measurements of heart rate; P-R interval; QRS duration; QTc interval; and P-, QRS-, and T-wave voltages were taken. The recordings were also examined for disturbances of conduction, rhythm, and repolarization. The acute and subacute phases were characterized by sinus tachycardia with depressed R- and T-wave voltages as well as disturbances of conduction, rhythm, and repolarization. In most animals in the chronic phase, the sinus rate returned to near-baseline values with resolution of the QRS voltage changes. The ECG changes observed during RbCV infection are similar to the spectrum of interval/segment abnormalities, rhythm disturbances, conduction defects, and myocardial pathology seen in human myocarditis, heart failure, and dilated cardiomyopathy. Because animals often died suddenly in the absence of severe clinical signs of congestive heart failure during the acute phase, RbCV infection may increase ventricular vulnerability, resulting in sudden cardiac death. RbCV infection may provide a rare opportunity to study sudden cardiac death in an animal model in which the ventricle is capable of supporting ventricular fibrillation, and invasive techniques monitoring cardiac function can be performed.

Keywords

coronavirus, myocarditis, heart failure, ECG

Adaptation of human enteric coronavirus to growth in cell lines

Journal of Clinical Virology
Volume 12, Issue 1, January 1999, Pages 43-51

J.ames P.Luby, R.ebecca Clinton, S.tanleyKurtz

Abstract

Background: The existence of human enteric coronavirus (HEC) has been debated since its first description in stool by electron microscopy (EM) in 1975. Needed to resolve the issue is its cultivation in readily available cell lines.

Objectives: To grow HEC in cell lines. To describe its characteristics and to differentiate it from other human and animal coronaviruses.

Study design: Originally grown in human fetal intestinal organ culture, HEC was passed in J774 cells (a mouse macrophage cell line) and C6/36 cells (a mosquito cell line). Its cytopathic effect (CPE) and pattern of immunofluorescence were described. Its appearance was ascertained by negative staining and transmission EM. Its structural proteins were delineated by polyacrylamide gel electrophoresis (PAGE) and Western blotting (WB). The antigenic character of the virus was determined by immunofluorescence and WB. Agglutination with mouse erythrocytes was performed.

Results: In J774 cells, HEC induced the formation of giant cells and small syncytia. Immunofluorescence in both J774 and C6/36 cells was limited to the cytoplasm. Studies with transmission EM revealed the virus to have the typical appearance of other coronaviruses, to be 80–120 nm in diameter, and to bud into cysternae of the endoplasmic reticulum. By PAGE and WB, its major protein has an average molecular weight (MW) of 41 kilodaltons (kDa). Two other proteins had MWs of 190 and 24 kDa. By immunofluorescence and WB, HEC is antigenically distinct from human coronaviruses 0C43 and 229E and mouse hepatitis virus (A59 strain). Preparations of HEC did not agglutinate mouse erythrocytes.

Conclusion: We conclude that HEC is a human coronavirus that is antigenically unrelated to 0C43 and 229E viruses. Growth of HEC in readily available cell lines should aid in elucidating its role as a pathogen in human diarrheal illnesses.

Keywords

Human enteric coronavirus, J774 cells, C6/36 cells, Adaptation, Growth in cell lines

Cellular composition, coronavirus antigen expression and production of specific antibodies in lesions in feline infectious peritonitis

Veterinary Immunology and Immunopathology
Volume 65, Issues 2–4, 23 October 1998, Pages 243-257

A. Kipar, S. Bellmann, J. Kremendahl, K. Köhler, M. Reinacher

Abstract

Twenty-three cats with spontaneous feline infectious peritonitis (FIP) were examined by light microscopy including immunohistology and histochemistry in order to determine the cellular composition and the expression of viral antigen in lesions in FIP. Furthermore, the presence of plasma-cells producing coronavirus-specific antibodies was evaluated in situ. Macrophages and neutrophils were demonstrated by an antibody against calprotectin (leukocyte protein L1, myeloid/histiocyte antigen), neutrophils were recognized due to their chloroacetate esterase activity, and B- and T-lymphocytes were identified by antibodies against the CD3 antigen and the CD45R antigen, respectively. Expression of viral antigen was immunohistologically demonstrated by a monoclonal antibody (mAb) against coronavirus while coronavirus-specific antibodies in situ were identified by the application of feline coronavirus prior to the coronavirus antibody. Lesions were classified as diffuse alterations at serosal surfaces, granulomas with areas of necrosis, granulomas without extended necrosis, focal and perivascular lymphoplasmocytic infiltrates, and granulomatous-necrotizing vasculitis. Diffuse alterations on serosal surfaces were represented either by activated mesothelial cells with single coronavirus antigen-bearing macrophages or by layers of precipitated exudate containing single to numerous granulomas with areas of necrosis. In liver and spleen, the exudate was often underlaid by a small band of subcapsular B-cells with an occasional plasma-cell producing coronavirus-specific antibodies. In other locations, a variably broad band of B-cells and plasma-cells, often infiltrating between underlying muscle fibers, separated the exudate from the unaltered tissue. Some of these plasma-cells were positive for coronavirus-specific antibodies. In granulomas with areas of necrosis, the central necrosis was surrounded by macrophages usually expressing considerable amounts of viral antigen. Few B-cells and plasma-cells were found in the periphery. In granulomas without extended necrosis, the number of macrophages were lower. Only few macrophages expressing low amounts of viral antigen were present. B-cells and plasma-cells formed a broad rim. Few plasma-cells stained positive for coronavirus-specific antibodies. In both types of granulomas, few neutrophils were found between macrophages. Few T-cells were seen scattered throughout the lesions. Focal and perivascular lymphoplasmocytic infiltrates were mainly seen in omentum and leptomeninx. B-cells were the predominant cells; some plasma-cells were positive for coronavirus-specific antibodies. Viral antigen was not readily detected in these alterations. Granulomatous-necrotizing vasculitis was occasionally found in kidneys and leptomeninx. It was dominated by macrophages which often stained strongly positive for coronavirus antigen. Different types of alteration were often seen in the same animal and even the same tissue. There was no obvious correlation between the cat's age, gross pathological changes, and the histological types of alteration. Single plasma-cells positive for coronavirus-specific antibodies were found around blood vessels distant from inflammatory alterations, within the lung parenchyma, as infiltrating cells in the mucosa of the small intestine, and in spleen and mesenteric lymph node. Results show that alterations in FIP are heterogeneous concerning cellular composition and expression of viral antigen. The dominance of B-cells in part of the lesions together with the presence of plasma-cells positive for coronavirus-specific antibodies indicate that these cells may play a role in the maintenance of inflammatory processes in FIP.

Keywords

Feline infectious peritonitis, Immunohistology, Coronavirus antigen, Coronavirus-specific antibodies, B-cells, Plasma-cells

Effects of the common cold on mood and performance

Psychoneuroendocrinology
Volume 23, Issue 7, October 1998, Pages 733-739

Andrew Smith, Marie Thomas, Julie Kent, Karl Nicholson

Abstract

Previous research has shown that both experimentally-induced and naturally occurring upper respiratory tract illnesses (URTIs) influence mood and mental functioning. None of the previous studies of naturally occurring colds has conducted appropriate virological assays to determine the nature of the infecting agent. This is an essential methodological step in studies of malaise associated with URTIs. The aim of this research was to investigate the effects of naturally occurring colds on mood and objective measures of performance. This was done by first conducting a cross-sectional comparison of 37 healthy people and 158 volunteers with colds and then a longitudinal study in which 100 volunteers developed colds and 87 remained healthy. Virological techniques were used to identify infecting agents and comparisons made across the different groups. The results showed that having a cold was associated with reduced alertness and slowed reaction times. These effects were observed both for colds where the infecting virus was identified and those where it was not. Similar effects were obtained for both rhinovirus and coronavirus colds. One may conclude that upper respiratory tract illnesses lead to a reduction in subjective alertness and impaired psychomotor functioning. This was true for both illnesses where the infecting agent was identified and for those clinical illnesses where no virus was detected. It is now important to identify the mechanisms linking infection and illness with the behavioural changes. Similarly, the impact of these effects on real-life activities such as driving needs examining. Finally, methods of treatment need to be developed which not only treat the local symptoms of the illnesses but remove the negative mood and the performance impairments.

Keywords

Common cold, Rhinovirus, Coronavirus, Reaction time, Alertness

Comparison of immunofluorescence with monoclonal antibodies and RT-PCR for the detection of human coronaviruses 229E and OC43 in cell culture

Journal of Virological Methods
Volume 72, Issue 2, June 1998, Pages 145-152

Jacques Sizun, Nathalie Arbour, Pierre J Talbot

Abstract

Human coronaviruses, with two known serogroups named 229E and OC43, cause up to one third of common colds and may be associated with serious diseases such as nosocomial respiratory infections, enterocolitis, pericarditis and neurological disorders. Reliable methods of detection in clinical samples are needed for a better understanding of their role in pathology. As a first step in the design of such diagnostic procedures, the sensitivities and specificities of two viral diagnostic assays were compared in an experimental cell culture model: an indirect immuno-fluorescence assay using monoclonal antibodies and reverse transcriptase-polymerase chain reaction amplification of viral RNA from infected cells. Immunofluorescence detected human coronaviruses in cells infected at a MOI as low as 10−2 (log TCID50/ml=4.25 for HCV-229E and 2.0 for HCV-OC43; log PFU/ml=4.83 for HCV-229E and 1.84 for HCV-OC43) versus 10−3 (HCV-OC43) or 10−4 (HCV-229E) for reverse transcriptase-polymerase chain reaction amplification (log TCID50/ml=1.75 for HCV-229E and 1.5 for HCV-OC43; log PFU/ml=2.3 for HCV-229E and 1.34 for HCV-OC43). There were no false positive signals with other human respiratory pathogens: influenza virus, respiratory syncytial virus and adenovirus. Moreover, each assay was coronavirus serogroup-specific. These results demonstrate the potential usefulness of immunofluorescence with monoclonal antibodies and reverse transcriptase-polymerase chain reaction RNA amplification for the rapid detection of human coronaviruses in infected cell cultures. Both methods could be applied to clinical specimens for the diagnosis of human infections.

Keywords

Coronavirus, 229E, OC43, Immunofluorescence, RT-PCR, Diagnostic

Roles in Cell-to-Cell Fusion of Two Conserved Hydrophobic Regions in the Murine Coronavirus Spike Protein

Virology
Volume 244, Issue 2, 10 May 1998, Pages 483-494

Zongli Luo, Susan R.Weiss

Abstract

The spike (S) protein of coronavirus, mouse hepatitis virus (MHV), mediates attachment and fusion during viral entry and cell-to-cell fusion later in infection. By analogy with other viral proteins that induce cell fusion the MHV S protein would be expected to have a hydrophobic stretch of amino acids that serves as a fusion peptide. Sequence analysis suggests that the S protein falls within the group of fusion proteins having internal rather than N-terminal fusion peptides. Based on the features of known viral fusion peptides, we identified two regions (PEP1 and PEP2) of MHV-A59 S2 as possible fusion peptides. Site-directed mutagenesis and an in vitrocell-to-cell fusion assay were used to evaluate the roles of PEP1 and PEP2, as well as a third previously identified putative fusion domain (PEP3) in membrane fusion. Substitution of bulky hydrophobic residues with charged residues within PEP1 affects the fusion activity of the S protein without affecting processing and surface expression. Similar substitutions within PEP2 result in a fusion-negative phenotype; however, these mutant S proteins also exhibit defects in protein processing and surface expression which likely explain the loss of the ability to induce fusion. Thus PEP1 remains a candidate fusion peptide, while PEP2 may play a significant role in the overall structure or oligomerization of the S protein. PEP3 is an unlikely putative fusion peptide since it is not conserved among coronaviruses and nonconservative amino acid substitutions in PEP3 have minimal effects on cell-to-cell fusion.

Keywords

cell-to-cell, coronavirus, mouse hepatitis virus, protein

Altered Pathogenesis of a Mutant of the Murine Coronavirus MHV-A59 Is Associated with a Q159L Amino Acid Substitution in the Spike Protein

Virology
Volume 239, Issue 1, 8 December 1997, Pages 1-10

Isabelle Leparc-Goffarta, Susan T.Hingley, Ming Ming Chua, Xinhe Jiang, EhudLavi, Susan R.Weiss

Abstract

C12, an attenuated, fusion delayed, very weakly hepatotropic mutant of mouse hepatitis virus strain A59 (MHV-A59) has been further characterized. We have previously shown that C12 has two amino acid substitutions relative to wild type virus in the spike protein, Q159L (within a region of S1 shown to bind to viral receptor in anin vitroassay) and H716D (in the proteolytic cleavage recognition site). We have sequenced the rest of the 31-kb genome of C12 and compared it to wild type virus. Only three additional amino acids substitutions were found, all encoded within the replicase gene. Analysis of C12in vivoin C57Bl/6 mice has shown that despite the fact that this virus replicates in the brain to titers at least as high as wild type and causes acute encephalitis similar to wild type, this virus causes a minimal level of demyelination and only at very high levels of virus inoculation. Thus acute encephalitis is not sufficient for the induction of demyelination by MHV-A59. Analysis of mutants isolated at earlier times from the same persistently infected glial cell culture as C12, as well as mutants isolated from a second independent culture of persistently infected glial cells, suggests that both the weakly demyelinating and the weakly hepatotropic phenotypes of C12 are associated with the Q159L amino acid substitution.

Keywords

pathogenesis, hepatitis virus, murine coronavirus MHV

Infectious Bovine Rhinotracheitis, Parainfluenza-3, and Respiratory Coronavirus

Veterinary Clinics of North America: Food Animal Practice
Volume 13, Issue 3, November 1997, Pages 455-469

Sanjay Kapil DVM, PhD, Randall J.Basaraba DVM, PhD

Abstract

A number of viruses have been proven to be primary respiratory pathogens of cattle. Viruses may play an important role in making cattle susceptible to secondary respiratory bacterial pathogens. Epidemiology, pathogenesis, laboratory diagnosis, and important properties in infectious bovine rhinotracheitis (IBR), parainfluenza-3 (PI-3), and bovine respiratory coronavirus (BRCV) are described in this article.

Keywords

rhinotracheitis, parainfluenza-3, bovine respiratory coronavirus

The Molecular Biology of Coronaviruses

Advances in Virus Research
Volume 48, 1997, Pages 1-100

Michael M.C. Lai, David Cavanagh

Abstract

This chapter discusses the manipulation of clones of coronavirus and of complementary DNAs (cDNAs) of defective-interfering (DI) RNAs to study coronavirus RNA replication, transcription, recombination, processing and transport of proteins, virion assembly, identification of cell receptors for coronaviruses, and processing of the polymerase. The nature of the coronavirus genome is nonsegmented, single-stranded, and positive-sense RNA. Its size ranges from 27 to 32 kb, which is significantly larger when compared with other RNA viruses. The gene encoding the large surface glycoprotein is up to 4.4 kb, encoding an imposing trimeric, highly glycosylated protein. This soars some 20 nm above the virion envelope, giving the virus the appearance-with a little imagination-of a crown or coronet. Coronavirus research has contributed to the understanding of many aspects of molecular biology in general, such as the mechanism of RNA synthesis, translational control, and protein transport and processing. It remains a treasure capable of generating unexpected insights.

Keywords

Coronavirus, DNAs, RNAs, clones

In vivo study of interferon-alpha-secreting cells in pig foetal lymphohaematopoietic organs following in utero TGEV coronavirus injection

Research in Immunology
Volume 148, Issue 4, May 1997, Pages 247-256

I.Splíchal, Z.Řeháková, M.Šinkora, J.Šinkora, I.Trebichavský, H.Laude, B.Charley

Abstract

Non-infectious UV-inactivated transmissible gastroenteritis virus (TGEV) was previously shown to induce interferon alpha (IFIMα) secretion following in vitro incubation with blood mononuclear cells. In this study, pig foetuses at different stages of gestation were injected in utero with (a) partially UV-inactivated wild TGEV or (b) fully UV-inactivated wild or dm49-4 mutant TGEV Coronavirus. Nucleated cells from foetal liver, bone marrow, spleen and blood were isolated 10 or 20 h after injection and assayed ex vivo for IFNα secretion by ELISPOT and ELISA techniques. The administration of TGEV induced IFNα-secreting cells in foetal lymphohaematopoietic organs at mid-gestation. In contrast, IFNα was not detected in control sham-operated foetuses. A specific point mutation in the amino acid sequence of the viral membrane glycoprotein M of TGEV mutant dm49-4 was associated with lower or absent IFNα in utero inducibility by mutant virus as compared with wild virus. Row cytometry analysis did not show differences in leukocyte surface marker expression between control and TGEV- or between dm49-4 and wild virus-treated foetus cells, with the exception of a reduction in percentages of polymorphonuclear cells in TGEV-treated lymphohaematopoietic tissues, which is probably due to IFNα secretion. The present data provided in vivo evidence of IFNα secretion at the cell level in foetal lymphohaematopoietic organs. Such IFNα-secreting cells in lymphohaematopoietic tissues may be the source of IFNα detected during foetal infections.

Keywords

Coronavirus, Transmissible gastroenteritis virus, IFNα, ELISA, ELISPOT, Foetus, Pig

Bovine coronavirus I protein synthesis follows ribosomal scanning on the bicistronic N mRNA

Virus Research
Volume 48, Issue 1, April 1997, Pages 101-105

Savithra D.Senanayake, David A.Brian

Abstract

The mRNA encoding the 49-kDa nucleocapsid protein (N) of the bovine coronavirus is bicistronic. A 23-kDa protein, termed the I protein for the ‘internal’ open reading frame (ORF), is also synthesized but in the +1 reading frame beginning 61 nt downstream of the N start codon. Sequences flanking the N and I start codons suggest that the I ORF might be accessed by scanning ribosomes passing over the N start codon. Here we test this idea and demonstrate with translation studies both in vitro and in vivo that the I protein is synthesized according to the leaky scanning model for initiation of translation on the subgenomic N mRNA molecule.

Keywords

Coronavirus bicistronic N mRNA, Nucleocapsid protein, Ribosomal scanning

Identification of the polymerase polyprotein products p72 and p65 of the murine coronavirus MHV-JHM

Virus Research
Volume 45, Issue 2, December 1996, Pages 101-109

Hong-QiangGao, Jennifer J.Schiller, Susan C.Baker

Abstract

The RNA polymerase gene of murine coronavirus MHV-JHM encodes a polyprotein of greater than 750 kDa. This polyprotein is proposed to be processed by two papain-like cysteine proteinases, PCP-1 and PCP-2, and a poliovirus 3C-like proteinase domain, 3C-pro, to generate protein products. The amino-terminal product of the MHV polymerase polyprotein, p28, is generated by cleavage of the polyprotein by PCP-1. To identify the viral products downstream of p28, we generated a fusion-protein specific antiserum directed against the region adjacent to p28 and used the antiserum to detect virus-specific proteins from MHV-JHM infected cells. When this antiserum was used to immunoprecipitate radiolabeled proteins from MHV-JHM infected cell lysates, virus-specific proteins of 72 and 65 kDa were detected. Furthermore, pulse and chase experiments demonstrated that p72 is likely a precursor to the mature protein product, p65. To investigate which viral proteinase may be responsible for generating p72 and p65, we expressed the 5′-region of the MHV-JHM RNA polymerase gene including the two papain-like cysteine proteinase domains in an in vitro transcription/translation system and analyzed the translation products for proteolytic processing. We also cloned and expressed the 72 kDa region immediately downstream from p28, and tested the ability of in vitro translated PCP-1 and PCP-2 to cleave p72 to p65 in trans. Our results indicate that neither viral proteinase domain PCP-1 nor PCP-2 is capable of cleavage of p72 to produce p65 in vitro. The role of MHV proteinases in the processing of p72 and p65 is discussed.

Keywords

Coronavirus, Polymerase polyprotein, Proteolytic processing

The Common Cold

Primary Care: Clinics in Office Practice
Volume 23, Issue 4, 1 December 1996, Pages 657-675

George L.KirkpatrickMD

Abstract

The common cold has intrigued physicians and the general public for centuries. It has been defined as an acute epidemic respiratory disease characterized by mild coryzal symptoms of rhinorrhea, nasal obstruction, and sneezing. The nasal discharge is usually copious and thin during the first 2 days of illness, then it generally becomes more viscous and purulent.22 The disease is self-limited. Symptoms may persist for 2 days to more than 14 days; however, the cold may abort after only 1 day. Fever, cough, sore throat, or lacrimation may or may not be present. The common cold is of itself harmless, but bacterial invasion frequently follows the initial infection. It is these secondary invaders that may produce disorders of serious consequence.

Keywords

common cold, epidemic, respiratory

Syncytia Formation Induced by Coronavirus Infection Is Associated with Fragmentation and Rearrangement of the Golgi Apparatus

Virology
Volume 221, Issue 2, 15 July 1996, Pages 325-334

EHUD LAVI, QIAN WANG, SUSAN R.WEISS, NICHOLAS K.GONATAS

Abstract

Coronavirus mouse hepatitis virus (MHV) possesses a membrane glycoprotein (M) which is targeted to the Golgi apparatus (GA). We used immunocytochemistry with an organelle-specific antiserum to investigate the morphologic changes of the GA during infection of L2 murine fibroblasts with MHV-A59. Twenty-four hours after infection the GA was fragmented and translocated in the center of syncytia, while the microtubular network was also rearranged displaying radiating elements toward the center of syncytia. Two fusion-defective mutants, which contain an identical amino acid substitution in the cleavage signal sequence of the spike glycoprotein (S), induced fragmentation of the GA. However, the GA migrated only partially to the centers of syncytia during infection with these mutants. Revertant viruses, in which the above mutation was corrected, had fusion properties and GA staining similar to wtMHV-A59. Experiments with brefeldin A (BFA), which induces redistribution of the GA into the rough endoplasmic reticulum (RER), revealed that an intact GA for a period of 4–16 hr postinfection, is required for coronavirus replication and syncytia formation. Thus, during MHV infection, syncytia formation is associated with fragmentation of the GA, followed by a previously undescribed phenomenon of migration of the organelle into the centers of syncytia. The fragmentation of the GA, however, may occur without the formation of syncytia. Therefore, two distinct mechanisms may be responsible for the fragmentation of the GA and its subsequent migration to the center of syncytia.

Keywords

corona virus, mouse hepatitis, golgi apparatus, glycoprotein