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