Lebombo virus 1 LEBV1 The only

serotype of Lebombo virus.

Lechiguanas virus A strain of Andes virus in the genus Hantavirus, isolated from Oligoryzomys flavescens. Has caused human cases of hantavirus pulmonary syndrome.

Le Dantec virus (LeDV) An unassigned species in the family Rhabdoviridae. With

Keuraliba virus forms serogroup 4, the Le Dantec group. Isolated in Senegal from a girl with liver and spleen enlargement. Confined to W Africa save for rare exceptions: a dock worker in Wales suffered a severe febrile illness after contracting Le Dantec virus infection following an insect bite while unloading a cargo from W Africa.

Lednice virus (LEDV) A strain of Turlock virus in the genus Bunyavirus. Isolated from mosquitoes, Culex modestus, in Moravia.

Lee virus (LEEV) A strain of Hantaan virus in the genus Hantavirus. Isolated in cell culture from the blood of a patient with Korean hemorrhagic fever in 1981, after passage in Apodemus agrarius.

Lee HW et al (1981) Am J Trop Med Hyg 30, 1106 Schmaljohn CS et al (1988) J Gen Virol 69, 1949

Lelystad virus Synonym for Porcine respiratory and reproductive syndrome virus.

Lenny virus A virus isolated from a case of disseminated vaccinia in a severely undernourished patient (Lenny Akpan) in Nigeria. Resembles the Wyeth strain of Vaccinia virus, producing mixed pocks on the CAM in 48 h, and replicating in rabbit skin; it does not produce pocks on the CAM above 38.5°C.

Burke ATC and Dumbell KR (1972) Bull Wld Hlth Org 46, 621

Lentivirinae (Latin: lentus=slow) Name for a proposed subfamily of the family Retroviridae; no longer used. See Lentivirus.

Lentivirus A genus in the family Retroviridae distinguished from other members of the family by differences in morphology and genetic complexity. Although lentivirus assembly and budding resembles that of type C retroviruses, the mature virions of lentivirus (ca. 100nm in diameter) differ in that they have a characteristic bar or cone-shaped nucleoid when visualized under the electron microscope. All lentiviruses contain several genes in addition to the gag, pol and env genes that encode the structural and enzymatic proteins of retroviruses. These differ in different lentiviruses. The type species HIV-1 has six additional genes termed vif, vpu, vpr, tat, rev and nef, whose products are involved in replication. In the HIV-2 and SIV genomes, the vpu gene is absent but a new gene, vpx, is present. Lenti-viruses from other animal species contain varying numbers of such additional genes. Five serogroups of lentiviruses have been recognized which reflect the host of origin, as given in Table L1.

Barker E et al (1995) In The Retroviridae, vol. 4, edited by JA Levy. New York: Plenum Press, p. 1

Coffin JM (1995) Science 267, 483 Cullen B (1998) Cell 93, 685 Miller RJ et al (2000) J Virol 74, 7187

Table L1. The five serogroups of lentiviruses

Serogroup Species

Bovine lentivirus Bovine immunodeficiency virus Equine lentivirus Equine infectious anemia virus Feline lentivirus Feline immunodeficiency virus

Puma lentivirus Ovine/caprine Caprine arthritis encephalitis lentivirus Visna/maedi virus

Primate lentivirus Human immunodeficiency virus 1 Human immunodeficiency virus 2

Simian immunodeficiency virus lentogenic strains A term used to describe mild or avirulent virus strains, especially of avian paramyxoviruses. Strains of Newcastle disease virus, for example, have been described as lentogenic (low virulence), mesogenic (medium virulence) or velogenic (high virulence).

leporid herpesvirus 1 (LeHV-1) A tentative species in the genus Rhadinovirus. An indigenous virus of the cottontail rabbit, Sylvilagus floridanus, in which it causes a lymphoproliferative disease in the young in 6-8 weeks.

Synonyms: cottontail rabbit herpesvirus; lagomorph herpesvirus 1; rabbit her-pesvirus.

Hinze HC (1971) Infect Immun 3, 350

leporid herpesvirus 2 (LeHV-2) A tentative species in the genus Rhadinovirus. A widespread silent infection of domestic rabbits, Oryctolagus sp; 'blind' passage of

leukoplakia the virus in rabbits leads to increased virulence and the ability to produce pericarditis and encephalitis. Other species are not susceptible. There is replication in rabbit cell cultures, but the virus has not yet been grown in eggs. Synonyms: herpesvirus cuniculi; Hinze virus; virus III of rabbits.

leporid herpesvirus 3 (LeHV-3) A tentative species in the genus Rhadinovirus. Genome sequencing studies indicate that this virus is a distinct species from lep-orid herpesvirus 1. Synonym: herpesvirus sylvilagus.

Medveczky MM et al (1989) J Virol 63, 1010

Leporipoxvirus A genus in the subfamily Chordopoxvirinae containing viruses of rabbits, hares and squirrels. Infectivity is ether-sensitive. DNA cross-hybridization occurs between species. Species show serological cross-reactivity. Hemagglutinin not produced. Mechanical transmission by arthropods is common. Type species is Myxoma virus; other species are Hare fibroma virus, Rabbit fibroma virus and Squirrel fibroma virus. Synonym: myxoma subgroup viruses.

Fenner F (1994) In Virus Infections of Rodents and Lagomorphs, edited by ADME Osterhaus. Amsterdam: Elsevier Sciences, p 51 McFadden G (1999) In Encyclopedia of Virology, Second edition, edited by A Granoff and RG Webster. London: Academic Press, p. 1381

lethal intestinal disease of infant mice virus A coronavirus which causes a severe disease in infant mice. They do not suckle, they lose weight, become lethargic and die after a short period of cyanosis. Older animals may have diarrhea. The disease can be produced in day-old mice by feeding virus. Antigenically distinct from epidemic diarrhea of infant mice virus.

Hierholzer JC et al (1979) Infect Immun 24, 508 Kraft LM (1962) Science 137, 282

leucine zipper An amino acid sequence of 30 residues with leucine at every seventh position. Found in DNA-binding proteins that interact with the CAAT box in the region of the leucine zipper and enhance transcription.

Landschutz HW et al (1988) Science 240, 1759

leucopenia An abnormally low count of circulating leucocytes, often seen as a result of virus infection.

leukemia viruses Members of the genera Alpharetrovirus, Gammaretrovirus or Deltaretrovirus. Isolated from many species of birds and mammals, the most extensively investigated being those from fowl, mice and cats. Do not transform cells in culture but will replicate in them. They cause leukemia of various types, depending upon the strain of virus and the strain of host animal, but usually have to be injected into newborn animals to induce the disease. The latent period before leukemia develops may be several months. They act as helpers for sarcoma viruses, coding for the envelope of the sarcoma virus, i.e. phenotypic mixing. Usually vertically transmitted, but can be passed between animals in close contact, especially in cats. There are intraspecies group-specific antigens and interspecies antigens. There is no cross-reaction between the avian and mammalian gs antigens. They can be grouped by their virus envelope antigens and by their tro-pism for cells of a particular genotype: for example, NIH Swiss (N tropic) and BALB/c (B tropic). Some passaged viruses are NB tropic. Avian virus differs from mouse and cat viruses in having prominent surface spikes. Strains vary in leukemogenic potential, and infection with viruses of low virulence may protect against strains of high virulence.

Hung Fan (1999) In Encyclopedia of Virology, Second edition, edited by A Granoff and RG Webster. London: Academic Press, p. 995

leukocyte-associated herpesvirus Synonym for cercopithecine herpesvirus 10, an unas-signed member of the family Herpesviridae.

Frank AL et al (1973) J Infect Dis 128, 618, 630

leukocytes Strictly, all white blood cells and their precursors of both the myeloid and lymphoid series. Often used especially for granulocytes (polymorphonuclear leukocytes) as distinct from lymphocytes.

leukoplakia Painless white patches up to 3 cm diameter on the mucosal or epithelial surfaces. Oral hairy leukoplakia seen in AIDS patients occurs on buccal mucosa leukoplakia

and squamous epithelial cells, which may contain actively replicating EBV.

Greenspan JS et al (1985) N Engl J Med 313, 1564

leukovirus An old name for a group of RNA tumor viruses now included in the family Retroviridae.

levamisole l-2,3,5,6,-Tetrahydro-6-phenyl-imidazo (2,l-b)-thiazole. An anthelmintic drug which boosts cell-mediated immunity. Thus, while not a directly antiviral agent, it may alter the course of virus infection. Has been used in recurrent her-petic lesions of the skin, and in children with frequent respiratory disease. Common side-effects are anorexia, diarrhea, irritability, fatigue, nausea and skin rashes.

Synonym: Ketarax.

L'Hoest monkey retrovirus A possible strain of Simian immunodeficiency virus in the genus Lentivirus. Originally isolated from a monkey in a North American zoo, then found by serological analysis in 57% of wild-caught L'Hoest monkeys, Cercopithecus lhoesti, from the Democratic Republic of the Congo.

Beer BE et al (2000) J Virol 74, 3892

ligase An enzyme that catalyzes the joining (ligation) of two different DNA or RNA molecules, or two ends of the same molecule, by a phosphodiester bond.

ligase chain reaction (LCR) A DNA probe amplification method.

Birkenmeyer LG and Mushahwar IK (1991) J Virol Meth 35,117

linker insertion mutagenesis The insertion of a linker molecule at restriction sites within an open reading frame. A linker of 3 bp (or multiples of 3) will maintain the reading frame beyond the insertion, or chain termination can be produced in all reading frames by insertion of other linkers.

lion lentivirus (FIV-Ple) A possible species in the genus Lentivirus. A survey of more than 400 free-ranging African and Asian lions, Panthera leo, revealed high seroprevalence of antibodies to Feline immunodeficiency virus (84% in the Serengeti and 91% in the Kruger National Park). Lion lentivirus was isolated by infection of lion lymphocytes in vitro, but the virus also causes a lytic infection in domestic cat T lymphoma cells. No evidence of immunodeficiency or other pathological effects of the infection has been found so far.

Brown EW et al (1994) J Virol 68, 5953 van deWoude S et al (1997) Virology 233, 185

lipoprotein A conjugated water-soluble protein containing a tightly bound lipid or group of lipids. Found in blood plasma, cell membranes, etc.

liposome An artificially prepared lipid vesicle used to introduce biological molecules (virus particles or nucleic acid) into cells. Liposomes may be uni- or multilamellar and of differing net surface charge depending on the method of production and their composition.

Poste G and Papahadjopoulos D (1976) Meth Cell Biol 14, 23

lipovirus Obtained during attempts to isolate and propagate the causal agent of human infectious hepatitis. Could be propagated, and caused changes in cells with which it was grown, but proved to be an ameboid cell and not a virus. Similar to a Hartmannellid ameba.

Dunnebacke TH and William RC (1967) Proc Natl Acad Sci 57, 1363

Lipovnik virus (LIPV) A serotype of Great Island virus in the genus Orbivirus, belonging to the Kemerovo serogroup. Isolated from the tick, Ixodes ricinus, in the former Czechoslovakia. Not known to cause disease in humans, but antibodies have been found in 18% of the inhabitants of Lipovnik.

Lipschutz bodies Intranuclear inclusion bodies found in cells infected with Human herpesvirus 1,2 or 3.

live attenuated virus Virus which has been attenuated to low virulence as compared to wild-type virus, e.g. the Sabin poliovirus vaccine strains, yellow fever vaccine 17D, measles Edmonston strain, etc. Often accomplished by passage of the

Lordsdale virus (LDV)

wild-type virus in an alternative host cell. In most cases the basis of the attenuation is not known.

live virus vaccines Vaccines containing virus which replicates in the recipient host but is of reduced virulence as compared to the original wild-type virus. Usually empirically derived by serial passage in cultured cells. Immunity is commonly stronger and longer-lasting than that following killed virus vaccines, although reversion to wild-type virulence is sometimes a problem even with licensed live vaccines (e.g. Sabin polio vaccine).

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