The pestiviruses: where do they belong?

In this introduction to the meeting, the author specifies the place of pestiviruses among RNA viruses and briefly summarizes the main characteristics from this genus.

Fatty acid acylation of viral proteins in murine hepatitis virus-infected cells. Brief report.

The fatty acid acylation of the cell-associated virus-specific proteins of mouse hepatitis virus (A 59-strain) was studied. 3H-palmitate label was associated with E2, one of the two virion glycoproteins and its intracellular precursor gp 150. A 110 K protein, the unglycosylated apoprotein of gp 150, accumulated by tunicamycin treatment, also incorporated radiolabeled palmitic acid.

The peplomers of Berne virus.

Using [3H]glucosamine and [3H]mannose labels, two virus-specific glycosylated polypeptide species with Mr values of about 200,000 (200K) and in the 75K to 100K range, respectively, were recognized in Berne virus-infected embryonic mule skin cells. In purified virions only the latter glycoprotein occurred. Concanavalin A was bound to the virion as evidenced by reduction in infectivity.

Surface proteins of Breda virus.

The serotypes 1 and 2 of Breda virus from feces of experimentally infected gnotobiotic calves were studied with respect to their sedimentation and density properties in sucrose gradients and their structural polypeptides; Berne virus, the proposed prototype of the new family Toroviridae, was included for comparison. After Breda-1 virus had been stored at 4 C for a prolonged period, it showed a heterogeneous sedimentation behavior (480 to 520 Svedberg units [S]) and density (1.18 to 1.

The peplomer protein sequence of the M41 strain of coronavirus IBV and its comparison with Beaudette strains.

The amino acid sequence of the gene for the peplomer protein of the vaccine strain M41 and the Beaudette laboratory strain M42-Salk of avian infectious bronchitis virus (IBV) have been derived from cDNA sequences. As found with other coronaviruses, the peplomer protein carries the epitopes eliciting neutralizing antibodies. The gene encodes a primary translation product of 1162 amino acids with a molecular weight of 128,079.

Equine arteritis virus-induced polypeptide synthesis.

Intracellular virus-specific proteins induced by equine arteritis virus (EAV) have been compared with in vitro translation products of virion and intracellular EAV RNAs. In infected BHK-21 cells, the two major virion proteins (C and E1) and polypeptides with mol. wt.

Intracellular equine arteritis virus (EAV)-specific RNAs contain common sequences.

Equine arteritis virus (EAV) is a nonarthropod-borne togavirus. Six virus-specific RNA species have been found in EAV-infected cells having the following molecular weights: 4.3 X 10(6) (RNA1), 1.

Morphogenesis of Berne virus (proposed family Toroviridae).

In equine dermis cells infected with Berne virus particles were first detected 10 h after infection. Virions were encountered in all parts of the Golgi system and, infrequently, in the rough endoplasmic reticulum. A unique form of budding of preassembled rigid tubular nucleocapsids was demonstrated.

Restricted replication of mouse hepatitis virus A59 in primary mouse brain astrocytes correlates with reduced pathogenicity.

Temperature-sensitive (ts) mutants of mouse hepatitis virus A59 (MHV-A59) are drastically attenuated in their pathogenic properties. Intracerebral inoculation of mice with 10(5) PFU of mutant ts342 results in prolonged infection of the central nervous system, whereas 100 PFU of wild-type virus are lethal (M. J.

Virion polypeptide specificity of immune complexes and antibodies in cats inoculated with feline infectious peritonitis virus.

Immune complexes purified from sera and ascitic fluids of cats after inoculation with feline infectious peritonitis (FIP) virus contained proteins and proteolytic fragments of the peplomer, nucleocapsid, and envelope polypeptides; in addition, host proteins were demonstrated in the immune complexes. Free (uncomplexed) antibodies against the 3 classes of virion polypeptides were detected and quantitated; the weakest and latest response was directed against the peplomer protein. Immunofluorescence titers showed the best correlation with the antibody response directed against the envelope polypeptides.

Characterization and translation of transmissible gastroenteritis virus mRNAs.

Three protein species were identified in purified transmissible gastroenteritis virus particles (strain Purdue). They are thought to represent constituents of the peplomer (E2; molecular weights of 280,000 and 240,000), the envelope (E1; molecular weights of 28,000, 31,500, and 33,000), and the nucleocapsid (N; molecular weight of 48,000). In infected cells, proteins with molecular weights of 195,000 (E2), 48,000 (N), and 28,000 (E1) were detected.

Resistance of Berne virus to physical and chemical treatment.

Thermal inactivation of Berne virus proceeded at a linear rate between 31 degrees and 43 degrees C. Storage at temperatures lower than -20 degrees C preserved the infectivity, while at 4 degrees C appreciable loss occurred between 92 and 185 days. Freeze-drying or desiccation at 22 degrees C caused only insignificant loss of infectivity.

[Feline infectious peritonitis].

This paper gives a summary of our present-day knowledge concerning etiology, clinical aspects, diagnosis, pathology and pathogenesis of feline infectious peritonitis. Special emphasis is given to the participation of the immune system in the development of lesions. A therapy protocol is proposed and an extensive list of original literature for further study is given.

The nucleocapsid of Berne virus.

In Berne virus-infected cells and in gradient-purified virions two major proteins with mol. wt. of 20K and 22K were detected.

Flaviviridae.

The family Flaviviridae comprises the genus Flavivirus, which contains 65 related species and two possible members. They are small, enveloped RNA viruses (diameter 45 nm) with peplomers comprising a single glycoprotein E. Other structural proteins are designated C (core) and M (membrane-like).

Togaviridae.

The family Togaviridae comprises four genera: Alphavirus (with 26 species), Rubivirus (one species), Pestivirus (three species), and Arterivirus (one species). The main characteristics of the member viruses are: (i) the virus particles are spherical, 50-70 nm in diameter, including an envelope with surface projections that incorporate two or three polypeptides, usually glycosylated; (ii) the nucleocapsid comprises a core protein and a single strand of positive-sense RNA, molecular weight about 4 X 10(6); where characterized, the RNA has an m7G 'cap' at the 5' end and is polyadenylated at the 3' end; (iii) maturation occurs by budding of spherical nucleocapsids 30-35 nm in diameter, with proven or presumed icosahedral symmetry, through cytoplasmic membranes. Where characterized, translation of structural proteins occurs on subgenomic messenger RNA(s); these appear to represent the 3' end of the genome.

Antibodies to Berne virus in horses and other animals.

After inoculation into 2 foals, Berne virus induced neutralizing antibody, but did not cause clinical symptoms. In a horizontal study of seropositive mares and their offspring, a decline of maternal antibodies and a sudden synchronous seroconversion in all foals were observed, again without clinical symptoms. The virus is widespread in the Swiss horse population and has been so during the last decade; rises in antibody titers were noted in 9% of paired sera sampled at random.

Berne virus is not 'coronavirus-like'.

In infected embryonic mule skin cells, Berne virus directs the synthesis of two main polypeptides (22K, 20K); in addition, virus-specific proteins with apparent molecular weights of greater than 200K, 80K to 120K, 32K and 17K were detected after radioimmune precipitation. The replication of Berne virus was reduced more than 1000-fold by actinomycin D, when the drug (0.1 to 1.

Persistent infection of some standard cell lines by lymphocytic choriomeningitis virus: transmission of infection by an intracellular agent.

Cell-free cytoplasmic extracts of the Syrian hamster cell lines C13/SV28 and BHK-21F were immunogenic in Syrian hamsters. The resulting antisera cross-reacted completely with antisera against lymphocytic choriomeningitis virus (LCMV) in an immunoradiometric assay employing BHK-21F antigen. Several other Syrian hamster cell lines not previously known to be infected with LCMV were also strongly positive when assayed for viral antigens.