R61837 compound A drug that inhibits replication of rhinovirus by preventing virus uncoating, probably by binding to the virus capsid. Effective intranasally in clinical trials against human rhinovirus.

R22 virus A strain of Seoul virus in the genus Hantavirus, isolated from Rattus norvegicus.

R plasmid A bacterial plasmid containing a gene for drug resistance.

rabbit calicivirus (RCV) A strain of Rabbit hemorrhagic disease virus in the genus Lagovirus. In contrast to RHDV, RCV appears to be apathogenic, causing an intestinal infection but not the severe liver and spleen necrosis seen with RHDV infection. The sequence of the capsid protein gene and antigenicity studies show that the two viruses are closely related, however.

Capucci L et al (1996) J Virol 70, 8614

rabbit coronavirus (RbCoV) A tentative species in the genus Coronavirus, first detected in 1970 in Sweden. Serologically related to Porcine hemagglutinating encephalomyelitis virus, mouse hepatitis virus, Bovine coronavirus, turkey blue comb coronavirus, sialodacryoadenitis virus of rats and Human coronaviruses 229E and OC-43. Causes severe symptoms in the eye (dullness of the scleras and congestion of conjunctivae), the heart (myocarditis with extensive calcification and dilation of the ventricles) and respiratory symptoms (pulmonary edema, pleural effusion) in rabbits. The rabbit coronavirus has been proposed as an experimental model for studies of myocarditis and congestive heart failure.

Edwards S et al (1992) J Infect Dis 165, 134

Rabbit fibroma virus (SFV) A species in the genus Leporipoxvirus. Antigenically closely related to Myxoma virus. Can be propagated on the CAM but no lesions are produced and the embryo is not infected. In cultures of rabbit, guinea pig, rat and human cells, replication occurs with CPE. The natural host is the wild cottontail rabbit, Sylvilagus floridanus, in which the virus causes benign fibromas, commonly on the feet. Virus can be extracted from the tumors and produces fibromas in wild and domestic rabbits on injection. See Berry-Dedrick phenomenon.

Synonyms: fibroma virus of rabbits; Shope fibroma virus.

Fenner F (1994) In Virus Infections of Rodents and Lagomorphs, edited by ADME Osterhaus. Amsterdam: Elsevier Science, p. 71

Rabbit hemorrhagic disease virus (RHDV)

The type species of the genus Lagovirus. A relatively new and economically important viral disease of wild and domestic rabbits and hares, outbreaks of which have appeared worldwide since 1984. Characteristic hemorrhages occur in many organs, e.g. trachea, lung, liver, kidney, spleen, peritoneum and pleura. Antigenically related to European brown hare syndrome virus, with which it shares a similar genome organization. Genome is 7437 bases long and includes two open reading frames (ORFs), one encoding a large polyprotein which includes the capsid protein as well as the non-structural proteins, and a smaller one encoding part of the polymerase gene and the complete capsid protein gene. This organization is different from other calicivirus genomes, which have three ORFs. There is a genome-linked protein (VPg) at the 5' terminus. Animal transmission studies have been performed to establish the host range of RHDV since it was considered in 1995 for use in a rabbit control program in Australia and New Zealand. More than 30 species were inoculated with large doses of virus but none showed evidence of infection except kiwis, which made antibodies against the virus but showed no clinical signs. During experimental testing of the effectiveness of RHDV in controlling rabbits on Wardang Island off S Australia,

rabbit type C endogenous virus the virus was accidentally transmitted to the mainland, where large numbers of rabbits have died of the calicivirus infection. Overall rabbit numbers have declined > 60% in Australia. In New Zealand, the virus was introduced illegally, probably by irate farmers who objected to a decision of the government not to allow legal importation of the virus until more was known about its potential host range. The emergence of rabbit calicivirus, which appears to be a non-pathogenic mutant of RHDV, may diminish the value of RHDV as a biological control agent.

Meyers G et al (2000) Virology 276, 349 Studdert MJ (1994) Aust Vet J 71, 264 Wirblich C et al (1996) J Virol 68, 5164

Table R1. Strains of rabbit hemorrhagic disease virus rabbit calicivirus rabbit hemorrhagic disease virus-AST89 (RHDV-AST89)

rabbit hemorrhagic disease virus-BS89 (RHDV-BS89) rabbit hemorrhagic disease virus-FRG (RHDV-FRG) rabbit hemorrhagic disease virus-SD (RHDV-SD) rabbit hemorrhagic disease virus-V351 (RHDV-V351)

rabbit herpesvirus Synonym for leporid herpesvirus 1.

Rabbit kidney vacuolating virus (RKV) A

species in the genus Polyomavirus. A natural and latent infection of cottontail rabbits, Sylvilagus floridanus. Not known to be pathogenic in any species. Agglutinates guinea pig erythrocytes at 4 and 20°C, by reacting with neuraminidase-sensitive receptors. Replicates, producing cell vacuolation, in domestic and cottontail rabbit kidney cell cultures but not in other species. Synonyms: polyomavirus sylvilagus; rabbit vacuolating virus.

Hartley JW and Rowe WP (1964) Science 143, 258

rabbit oral papillomavirus (ROPV) A possible species in the genus Papillomavirus. Antigenically different from Cottontail rabbit papillomavirus. A natural infection of domestic rabbits causing papillomas, usually beneath the tongue, which regress in a month or two. On inoculation into the oral mucosa, papillomas appear in 6-38

days. Will not produce skin warts. Sylvilagus and Lepus can be infected.

Parsons RJ and Kidd J (1943) J Exp Med 77, 233

rabbit papillomavirus See Cottontail rabbit papillomavirus.

rabbit parvovirus Synonym for Lapine parvovirus.

rabbit plague virus Synonym for rabbitpox virus.

rabbitpox virus (RPXV) A strain of Vaccinia virus in the genus Orthopoxvirus. A laboratory artifact due to infection of colonized rabbits with Vaccinia virus. No natural reservoir. After infection by the respiratory route causes usually lethal generalized disease. Synonym: rabbit plague virus.

rabbit reticulocyte lysate A cell-free system prepared from lyzed rabbit reticulocytes which is used for the translation of eukaryotic mRNAs. The rabbit is made anemic by injection with acetyl phenyl-hydrazine and the reticulocytes extracted. After lysis the endogenous mRNAs are destroyed using micrococcal nuclease which is then inactivated by the addition of EGTA (ethylene-glycolbis (aminoethylether)tetra-acetic acid). Translation in the extract is then totally dependent upon added mRNA. See wheat germ extract.

McCrae M (1985) In Virology: A Practical Approach, edited by BWJ Mahy. Oxford: IRL Press, p. 167

rabbit type C endogenous virus A possible species in the genus Gammaretrovirus. When primary lymphosarcoma cell cultures from WH/J rabbits were treated with idoxuridine, C-type virus particles were produced which contained RNA-dependent DNA polymerase and a p30 structural protein. These proteins shared antigenic homologies with other mammalian group viruses but also possessed unique antigenic determinants. There was evidence that viral genetic information was present in the WH/J rabbit cells. These rabbits developed spontaneous lymphosarcomas.

Bedigian HG et al (1978) J Virol 27, 313

rabbit vacuolating virus

rabbit vacuolating virus Synonym for Rabbit kidney vacuolating virus.

Rabies virus (RABV) A species in the genus Lyssavirus. The natural hosts are many bat species and terrestrial carnivores, but most mammals can be infected. In dogs the incubation period is from 10 days to more than 6 months; in humans usually from 15 days to 5 months, but incubation periods as long as several years have been documented. Dogs at first show excitement or aggression with hypersali-vation and often bite (furious rabies), later depression and paralysis (dumb rabies) and soon die. The same two stages may be seen in humans, with about 20% of cases being mainly paralytic, especially after exposure to bat strains. In cattle and horses the signs are variable and diagnosis may be difficult. In all species recovery from disease is extremely rare. The saliva of infected animals is highly infectious, and bites are the usual means of transmission although infection through superficial skin lesions is possible. The natural reservoir of infection varies: in Europe the fox is the most important. After the Second World War foxes became much more numerous and the virus was able to spread slowly from Poland across Europe. Control measures involving the use of oral bait vaccines have been effective in reducing fox rabies in most European countries. In the former USSR the wolf, in S Africa the mongoose, in India the jackal, and in S and Central America the vampire bat are important reservoirs of infection. In the USA skunks, foxes, bats, coyotes and raccoons spread rabies. Insular areas such as Hawaii and Australia are kept free of rabies by a 6-month quarantine of imported cats and dogs. This was also the situation in the UK until recently, when the Channel Tunnel was opened. All laboratory animals can be infected and die. There is encephalitis, especially of the midbrain, cerebellum and medulla. Negri bodies are present in nerve cells. Diagnosis is with fluorescein-labeled antirabies antibody staining of brain tissue taken at necropsy. The virus can be replicated in most tissues of the embryo-nated egg and in a wide range of primary and continuous cell cultures. CPE is rare. The animal reservoir of an isolate of

Rabies virus can be determined using monoclonal antibody panels and nucleotide sequence analysis. Early diagnosis in humans depends primarily on a history of a bite from an animal proved to have rabies, since the first clinical signs are non-specific. Late in the course of the infection, virus replicates in other tissues besides the CNS and brain, and can be demonstrated by fluorescent antibody or by isolation in saliva, corneal epithelium and cutaneous nerves in skin biopsy, but this is too late for post-exposure treatment. On passage by i.c. injection in laboratory rabbits the wild virus ('street' virus) becomes lethal in 4-6 days. This now called 'fixed' virus was attenuated by desiccation of the spinal cord to become the vaccine used by Louis Pasteur. Modern rabies vaccines for humans and animals are chemically inactivated purified virus from cell culture. For prevention of rabies after animal bites (post-exposure prophylaxis, PEP) rabies immunuglobulin (RIG) is given with five doses of vaccine.

Synonyms: hydrophobia virus; lyssa virus; rage virus; tollwut virus; wut virus.

Mebatsion T et al (1999) J Virol 73, 242 Rupprecht CE et al (1994) Curr Top Microbiol Immun 187, 352 pp

Tordo et al (1998) In Virology, vol. 1 of Topley & Wilson's Microbiology and Microbial Infections, Ninth edition, edited by BWJ Mahy and L Collier. London: Arnold, p. 665

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