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Revision as of 15:52, 9 June 2015

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]

Synonyms and keywords: Lassa hemorrhagic fever; LHF

Overview

Lassa fever is caused by the Lassa virus, a member of the Arenaviridae family. It is an enveloped, single-stranded, bisegmented RNA virus. Mastomysrodents shed the virus in urine and droppings. The direct contact with these materials or ingestion or inhalation, can lead to infection. Lassa virus enters the cell by the receptor-mediated endocytosis and undergoes very rapid replication and manifest the disease.

Causes

Taxonomy

Viruses; ssRNA viruses; ssRNA negative-strand viruses; Arenaviridae; Mammarenavirus ^[1]

Biology

Lassa virus belongs to Arenaviridae ^[2].
The Arenaviridae are a family of viruses whose members are generally associated with rodent-transmitted diseases in humans. Each virus usually is associated with a particular rodent host species in which it is maintained.

Structure

Lassa virus is an enveloped, single-stranded, bisegmented, ambisense RNA virus.

Genome

Lassa virus genome is contained in two RNA segments, each of which encodes 2 viral proteins (total 4 viral proteins)^[3]^[4]
- The large segment encodes RNA polymerase (L) and a small zinc-binding protein (Z) that regulates transcription and replication^[5]^[6]
- The small segment encodes the nucleoprotein (NP) and the surface glycoprotein precursor (GP or viral spike). The GP protein is cleaved into the envelope glycoproteins, GP1 and GP2, that bind to the alpha-dystroglycan receptor and mediate host cell entry^[7]
Nucleotide studies of the genome have shown that Lassa has four lineages: Three in Nigeria and a fourth in Guinea, Liberia, and Sierra Leone. The Nigerian strains are thought to be ancestral to the others.^[8].

Natural Reservoir

The most common natural reservoir of Lassa virus is the rodent, Mastomys natalensis. Mastomys natalensis is commonly known as the “multimammate rat” due to the female’s multiple and prominent mammary glands.
The mastomys rodents are abundant in the Savannas and forests of West, Central, and East Africa.
Once infected, the rodent is able to excrete the virus in the urine and feces for an extended time period. Mastomys rodents breed frequently, produce large numbers of offspring, and commonly inhabit human homes with food storage. All of these factors contribute to the relatively efficient spread of Lassa virus from infected rodents to humans.

Mastomys natalensis or the natal multimammate mouse.^[9]

Mastomys natalensis is commonly known as the “multimammate rat” due to the female’s multiple and prominent mammary glands.^[9]

Gallery

The images below display key features of the Lassa virus.

This transmission electron micrograph (TEM) demonstrates Lassa virus virions adjacent to host cell debris.Retrieved from the Public Health Image Library (PHIL), Centers for Disease Control and Prevention.^[10]
This highly magnified transmission electron micrograph (TEM) demonstrates ultrastructural details of 3 Lassa virus virions.Retrieved from the Public Health Image Library (PHIL), Centers for Disease Control and Prevention.^[10]
This transmission electron micrograph depicted eight virions (viral particles) of an Arenavirus.Retrieved from the Public Health Image Library (PHIL), Centers for Disease Control and Prevention.^[10]

References

↑ "Taxonomy browser (Lassavirus)".
↑ "The Centers for Disease Control and Prevention".
↑ "Genome:The autobiography of a species in 23 chapters". Nat Genet. 24 (1): 21. 2000. doi:10.1038/71638. PMID 10615121.
↑ Moshkoff DA, Salvato MS, Lukashevich IS (2007). "Molecular characterization of a reassortant virus derived from Lassa and Mopeia viruses". Virus Genes. 34 (2): 169–76. doi:10.1007/s11262-006-0050-3. PMC 1892610. PMID 17143722.
↑ Cornu TI, de la Torre JC (2001). "RING finger Z protein of lymphocytic choriomeningitis virus (LCMV) inhibits transcription and RNA replication of an LCMV S-segment minigenome". J Virol. 75 (19): 9415–26. doi:10.1128/JVI.75.19.9415-9426.2001. PMC 114509. PMID 11533204.CS1 maint: PMC format (link)
↑ Djavani M, Lukashevich IS, Sanchez A, Nichol ST, Salvato MS (1997). "Completion of the Lassa fever virus sequence and identification of a RING finger open reading frame at the L RNA 5' End". Virology. 235 (2): 414–8. doi:10.1006/viro.1997.8722. PMID 9281522.
↑ Smelt SC, Borrow P, Kunz S, Cao W, Tishon A, Lewicki H; et al. (2001). "Differences in affinity of binding of lymphocytic choriomeningitis virus strains to the cellular receptor alpha-dystroglycan correlate with viral tropism and disease kinetics". J Virol. 75 (1): 448–57. doi:10.1128/JVI.75.1.448-457.2001. PMC 113937. PMID 11119613.
↑ Bowen MD, Rollin PE, Ksiazek TG, Hustad HL, Bausch DG, Demby AH; et al. (2000). "Genetic diversity among Lassa virus strains". J Virol. 74 (15): 6992–7004. PMC 112216. PMID 10888638.
↑ ^9.0 ^9.1 "Wikipedia Natal multimammate mouse".
↑ ^10.0 ^10.1 ^10.2 "Public Health Image Library (PHIL), Centers for Disease Control and Prevention".

Template:WikiDoc Sources

[1] "Taxonomy browser (Lassavirus)".

[NCCN-2] "The Centers for Disease Control and Prevention".

[pmid10615121-3] "Genome:The autobiography of a species in 23 chapters". Nat Genet. 24 (1): 21. 2000. doi:10.1038/71638. PMID 10615121.

[pmid17143722-4] Moshkoff DA, Salvato MS, Lukashevich IS (2007). "Molecular characterization of a reassortant virus derived from Lassa and Mopeia viruses". Virus Genes. 34 (2): 169–76. doi:10.1007/s11262-006-0050-3. PMC 1892610. PMID 17143722.

[pmid11533204-5] Cornu TI, de la Torre JC (2001). "RING finger Z protein of lymphocytic choriomeningitis virus (LCMV) inhibits transcription and RNA replication of an LCMV S-segment minigenome". J Virol. 75 (19): 9415–26. doi:10.1128/JVI.75.19.9415-9426.2001. PMC 114509. PMID 11533204.CS1 maint: PMC format (link)

[pmid9281522-6] Djavani M, Lukashevich IS, Sanchez A, Nichol ST, Salvato MS (1997). "Completion of the Lassa fever virus sequence and identification of a RING finger open reading frame at the L RNA 5' End". Virology. 235 (2): 414–8. doi:10.1006/viro.1997.8722. PMID 9281522.

[pmid11119613-7] Smelt SC, Borrow P, Kunz S, Cao W, Tishon A, Lewicki H; et al. (2001). "Differences in affinity of binding of lymphocytic choriomeningitis virus strains to the cellular receptor alpha-dystroglycan correlate with viral tropism and disease kinetics". J Virol. 75 (1): 448–57. doi:10.1128/JVI.75.1.448-457.2001. PMC 113937. PMID 11119613.

[pmid10888638-8] Bowen MD, Rollin PE, Ksiazek TG, Hustad HL, Bausch DG, Demby AH; et al. (2000). "Genetic diversity among Lassa virus strains". J Virol. 74 (15): 6992–7004. PMC 112216. PMID 10888638.

[Wikipedia_Natal_multimammate_mouse-9] 9.0 ^9.1 "Wikipedia Natal multimammate mouse".

[PHIL-10] 10.0 ^10.1 ^10.2 "Public Health Image Library (PHIL), Centers for Disease Control and Prevention".

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@@ Line 16: / Line 16: @@
 ===Structure===
 * Lassa virus is an enveloped, [[single-stranded]], bisegmented, ambisense [[RNA virus]].
 ===Genome===
@@ Line 27: / Line 26: @@
 *The most common natural [[reservoir]] of Lassa virus is the [[rodent]], Mastomys natalensis. Mastomys natalensis is commonly known as the “multimammate rat” due to the female’s multiple and prominent mammary glands.
 *The mastomys rodents are abundant in the Savannas and forests of West, Central, and East Africa.
+*Once infected, the rodent is able to [[excrete]] the [[virus]] in the [[urine]] and feces for an extended time period. Mastomys rodents breed frequently, produce large numbers of offspring, and commonly inhabit human homes with food storage. All of these factors contribute to the relatively efficient spread of Lassa virus from [[infected]] [[rodents]] to [[humans]].
-*Once infected, the rodent is able to [[excrete]] the [[virus]] in the [[urine]] for an extended time period. Mastomys rodents breed frequently, produce large numbers of offspring, and commonly inhabit human homes with food storage. All of these factors contribute to the relatively efficient spread of Lassa virus from [[infected]] [[rodents]] to [[humans]].
 {|
 | valign=top |
-[[File:Mastomys natalensis.jpg|thumb|center|400 px|Mastomys natalensis or the natal multimammate mouse.<ref name="Wikipedia Natal multimammate mouse">{{Cite web | title = Wikipedia Natal multimammate mouse| url =  http://en.wikipedia.org/wiki/Natal_multimammate_mouse}}</ref>]]
+[[File:Mastomys natalensis.jpg|thumb|400 px|Mastomys natalensis or the natal multimammate mouse.<ref name="Wikipedia Natal multimammate mouse">{{Cite web | title = Wikipedia Natal multimammate mouse| url =  http://en.wikipedia.org/wiki/Natal_multimammate_mouse}}</ref>]]
 |style="width: 300px"|
-| [[File:Mastomys natalensis mammary.jpg|thumb|center|400 px|Mastomys natalensis is commonly known as the “multimammate rat” due to the female’s multiple and prominent mammary glands.<ref name="Wikipedia Natal multimammate mouse">{{Cite web | title = Wikipedia Natal multimammate mouse| url =  http://en.wikipedia.org/wiki/Natal_multimammate_mouse}}</ref>]]
+| [[File:Mastomys natalensis mammary.jpg|thumb|400 px|Mastomys natalensis is commonly known as the “multimammate rat” due to the female’s multiple and prominent mammary glands.<ref name="Wikipedia Natal multimammate mouse">{{Cite web | title = Wikipedia Natal multimammate mouse| url =  http://en.wikipedia.org/wiki/Natal_multimammate_mouse}}</ref>]]
 |}
-* Mastomysrodents shed the [[virus]] in [[urine]] and droppings and direct contact with these materials, through touching soiled objects, eating contaminated [[food]], or exposure to open [[cuts]] or [[sores]], can lead to [[infection]]. Because Mastomys rodents often live in and around homes and scavenge on leftover human food items or poorly stored food, direct contact [[transmission]] is common. Mastomys [[rodents]] are sometimes consumed as a food source and [[infection]] may occur when [[rodents]] are caught and prepared. Contact with the [[virus]] may also occur when a person inhales tiny particles in the air contaminated with infected [[rodent]] excretions.
 ==Gallery==