Identification of Gene, Function & Pathogen

Question starts from:

gctcgtgcga gcgggcctac cgacggccgc gcggcgtccc 421 gtcctagcca tcgccagggg gcctccgaag cccgcgggga tccggagctg cccacgctgc 481 tgcgggttta tatagacgga ccccacgggg tggggaagac caccacctcc gcgcagctga 541 tggaggccct ggggccgcgc gacaatatcg tctacgtccc cgagccgatg acttactggc 601 aggtgctggg ggcctccgag accctgacga acatctacaa cacgcagcac cgtctggacc 661 gcggcgagat atcggccggg gaggcggcgg tggtaatgac cagcgcccag ataacaatga 721 gcacgcctta tgcggcgacg gacgccgttt tggctcctca tatcgggggg gaggctgtgg 781 gcccgcaagc cccgcccccg gccctcaccc ttgttttcga ccggcaccct atcgcctccc 841 tgctgtgcta cccggccgcg cggtacctca tgggaagcat gaccccccag gccgtgttgg 901 cgttcgtggc cctcatgccc ccgaccgcgc ccggcacgaa cctggtcctg ggtgtccttc 961 cggaggccga acacgccgac cgcctggcca gacgccaacg cccgggcgag cggcttgacc 1021 tggccatgct gtccgccatt cgccgtgtct acgatctact cgccaacacg gtgcggtacc 1081 tgcagcgcgg cgggaggtgg cgggaggact

• Gene Name: TK


• Protein Name: Thymidine kinase (Also known as: EC 2.7.1.21)
  


• Gene Function:
  1. Thymidine kinase activity. Catalysis of the reaction: ATP + thymidine = ADP + thymidine 5'-phosphate.
  2. ATP binding. Interacting selectively with ATP, adenosine 5'-triphosphate, a universally important coenzyme and enzyme regulator.


• Protein Function:
  In latent infection, thymidine kinase protein may allow the virus to be reactivated and to grow in cells lacking a high concentration of phosphorylated nucleic acid precursors, such as nerve cells that do not replicate their genome .

Figure: Human Herpesvirus.
CST: Urinary Tract Infections and Sexually Transmitted Infections.

• Pathogen: Human herpesvirus 2 strain 333
  Taxonomy ID: 10313
  Rank: no ranks
  Genetic code: Translation table 1 (Standard)
  Other names:
  synonym: Herpes simplex virus (type 2 / strain 333)
  synonym: human herpesvirus 2 (strain 333)
  Lineage( full )
  Viruses; dsDNA viruses, no RNA stage; Herpesviridae; Alphaherpesvirinae; Simplexvirus; Human herpesvirus 2

References:
1. UniProtKB, April 8, 2008: Reviewed, UniProtKB/Swiss-Prot P04407(KITH_HHV23). Internet: http://beta.uniprot.org/uniprot/P04407.
2. EMBL-EBI, 1995: IPR001889 Herpesvirus thymidine kinase. Internet: http://www.ebi.ac.uk/interpro/ISearch?mode=ipr&query=IPR001889.
3. NCBI: Human Herpesvirus 2 strain 333. Internet: http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=10313&lvl=3&lin=f&keep=1&srchmode=1&unlock.
4. NCBI: X01712. Internet: http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?val=59898.

Comments and inquiries are always welcome.

Prepared by Tan Phit Ling 1071114866

Biologic Characteristic

Figure : Electron Micrograph Images of Herpesvirus
Linda M Stannard, 1995: DNA-containing viruses.

Figure: Structure of HSV
Kenty: Herpes.

• Herpes simplexvirus-2 (HSV-2) is a neurotropic and neuroinvasive virus, which is the most common cause of genital herpes, a sexually transmitted infection that results in the intermittent outbreak of a painful vesicular skin eruption on the genitalia.

Figure : Icosahedron capsid
Linda M Stannard, 1995: Herpesvirus.

Figure : When the envelope breaks and collapses away from the capsid, negatively stained virions have a typical "fried-egg" appearance.
Linda M Stannard, 1995: Herpesvirus.

• HSV-2 has a relatively large double stranded, linear DNA genome surrounded within an icosahedral capsid, which is wrapped in an envelope. The envelope is joined to the capsid by a tegument. This complete particle is known as the virion (negatively stained).

Figure : The glycoprotein B (gB) is clearly visualized in clusters of spikes approximately 10 nm in length.
Linda M Stannard, 1995: Herpesvirus.

• HSV-2 has no RNA stage. Its family is Herpesviridae and its subfamily is Alphaherpesvirinae as HSV-2 can reproduce quickly. HSV-2 is able to escape the immune response and persists indefinitely in a latent state in certain tissues. Reactivation of the virus is due to the effects of other illnesses such as cold and influenza, eczema, menstruation, emotional and physical stress, it may bring more severe effects than the primary infection.

References:

1. Wikipedia, April 2008: Herpes Simplex Virus. Internet: http://en.wikipedia.org/wiki/Herpes_simplex_virus#External_links.
2. Linda M Stannard, 1995: Herpesvirus. Internet: http://web.uct.ac.za/depts/mmi/stannard/herpes.html.
3. Kenty: Herpes. Internet: http://life.nthu.edu.tw/~b871614/articles/final%20report/herpes.htm.

Comments and inquiries are always welcome.

Prepared by Wong Li Chin 1071113696

Reservoir & Transmission

• Reservoir:
  
  

  Figure: Harboring herpesvirus.
  CST: Urinary Tract Infections and Sexually Transmitted Infections.

  
  Herpes simplex virus type 2 only naturally occur in human. HSV-2 remains dormant in the sacral ganglia at the base of the spine after it has entered the body. From there, it recurs in the genital area.

• Transmission:
  Herpes simplex virus type 2 can be passed in the urine or genital discharge of an infected person. It may also transmitted through the rubbing of genital skin during sexual activity (shedding virus from the skin).
  
  More oftenly HSV-2 is transmitted during sexual intercouse with an infected person. The virus is more easily transmitted to women than men with the greater risk of skin breakage in vaginal tissues with intercourse, making exposure more efficient. Rates also correlate with number of sexual partners.
  

  

  
  Figure: Infected mother gives birth to congenital infected child.
  Lifespan, 2007: Herpes Simplex.

  
  There are cases of transmission of HSV-2 occur during labor and delivery. For every 10 neonatal herpes infections, 6 to 7 are acquired because the mother acquires an asymptomatic first outbreak. Transmission of the herpes simplex virus to a newborn can have devastating effects. The extent of the herpes simplex infection can range from a rash on the skin, to involvement of the eyes and mouth, to infection of the brain, to infection throughout the body.
  
  The risk of herpes spreading from person to person is high just before, during and for the week following an outbreak of herpes. However, the herpes virus can be passed from person to person without any active ulcer or blister being present. This means that even when a person is free of symptoms, the virus can still spread to another person if the infected person happens to be shedding herpes virus at the time of sexual intercourse or during labor.
  

References:
1. MedHelp: Herpes FAQ. Internet: http://www.medhelp.org/HealthTopics/questions/faq-herpes-q3.htm.
2. Biogetica: Herpes Simplex Virus 2. Internet: http://biogetica.com/herpes-simplex-virus2.html.
3. Queensland Government, 8 February, 2007: Genital Herpes. Internet: http://www.health.qld.gov.au/sexhealth/factsheets.shtml.
4. Lifespan, 2007: Herpes Simplex. Internet: http://www.lifespan.org/adam/graphics/images/en/17145.jpg.
5. CST: Urinary Tract Infections and Sexually Transmitted Infections. Internet: www.cst.cmich.edu/users/Alm1EW/MMUTI&STD.html.
6. EMBL-EBI: Human Herpesvirus. Internet: http://www.ebi.ac.uk/2can/genomes/viruses/Human_herpesvirus.html.

Comments and inquiries are always welcome.

Prepared by Tan Phit Ling 1071114866

Virulence Factors

Figure: Symptoms of infected patient.

References:
1. Wikipedia, 2008: Genital Infection. Internet: http://en.wikipedia.org/wiki/Herpes_simplex#Genital_infection
2. Wikipedia, 2008: Herpes simple virus. Internet: http://en.wikipedia.org/wiki/Herpes_simplex_virus
3. Dr. Wagner, October 2003: Herpes Simplex Virus Research. Internet: http://darwin.bio.uci.edu/~faculty/wagner/hsv4f.html
4. eMedicineHealth, 26 January, 2007: Genital Herpes. Internet: http://www.emedicinehealth.com/genital_herpes/article_em.htm
5. Derek Wong: Pathogenesis of Herpes Simplex Virus Infection. Internet: http://virology-online.com/viruses/HSV2.htm
6. Virusys: HSV information. Internet: http://www.virusys.com/herpes-simplex-virus-type-1-(hsv%111)/hsv%111-information/hsv-information/

Comments and inquiries are always welcome.

Prepared by Tai Chu Cheng 1061107241

Pathogenesis

Figure: Pathogenesis of HSV.
Dr. Edward K. Wagner, October 2003: HSV Replication.

• Cellular entry
  · Generally, entry of viral into the host cell involves interactions of
  
  * Glycoproteins on the surface of the virus &
  * Receptors on the surface of the host cell.
  · For cellular entry of herpes virus, a glycoprotein embedded in the viral envelope, glycoprotein C binds to the heparan sulfate on the surface of the host cell, provides an initial contacts between viral and host cell.
  · A second glycoprotein, glycoprotein D, binds specifically to the herpesvirus entry mediator receptor (HVEM), provides a strong, fixed attachment with the host cell.
  · This brings viral and hose cell into closeness, allows other glycoproteins embedded in the viral envelope to interact with other cell surface particle.
  · Once bound to the HVEM, glycoprotein D changes its conformation and interacts with viral glycoproteins H and L, which form a complex.
  · The interaction of these membrane proteins results in a hemifusion state.
  · Glycoproteins B was then interact with this complex, creates a stable entry pore, allows the introduction of viral capsid into the host cell.
  

Figure: Herpes enters its target cell by membrane fusion.
CST: Urinary Tract Infections and Sexually Transmitted Infections.

• Genetic inoculation
  · Once the viral capsid enters the cellular cytoplasm, it is carried to the cell nucleus.
  · The viral capsid ejects its DNA contents into the nucleus via capsid portal
  · The capsid portal is formed by 12 copies of portal protein, UL6, which arranged as a ring; the proteins contain a leucine zipper sequence of amino acids which allow them to adhere to each other.
  · The DNA exits the capsid and goes into the host’s nucleus cell in a single linear segment.
  


• Genome Replication
  · Virus genome is accompanied by the a-TIF protein which functions in enhancing immediate-early viral transcription via cellular transcription factors.
  · In the nucleus, genome transcription is sequentially regulated in a cascade fashion. Approximately 50 mRNAs are produced by host cell RNA polymerase II.
  · Three distinct classes of mRNAs are made:

  * immediate early (IE) mRNAs - 5 trans-acting regulators of virus transcription
  * Early mRNAs - Further non-structural regulatory proteins & minor structural proteins
  * Late mRNAs - Major structural proteins

  · Both IE and E proteins are required for genome replication.
  · The E proteins are used in the regulation of genetic replication of the virus.
  · The virion host shutoff protein (VHS or UL41) is very important to viral replication. It shuts off protein synthesis in the host cell, degrades host mRNA, helps in viral replication, and regulates gene expression of viral proteins.
  · The late proteins transcribed are used in forming the capsid and the receptors on the surface of the virus.
  · Packaging of the viral particles - including the genome, core and the capsid - occurs in the nucleus of the cell.
  · Here, concatemers of the viral genome are separated by cleavage and are placed into pre-formed capsids.
  


• Latent infection
  · HSV may persist in a quiescent but persistent form known as latent infection
  · During latent infection of a cell, HSV express Latency Associated Transcript (LAT) RNA.
  · Consequences of LAT production interfere with the following process:

  * The metabolism of the host cell is disrupted.
  * While the infected cell would ordinarily undergo an organized death or be removed by the immune system.

  · LAT expression preserves a reservoir of the virus, which allows later recurrences to produce further infections.
  · During latency, most of the Herpes DNA is inactive, with limited expression of specific virus genes required for the maintenance of latency
  · HSV-II establishes latency in sensory nerve ganglia during severe infection and may later periodically reactivate from lumbosacral dorsal root ganglia (DRG) to cause recurrent disease.
  


• Reactivation
  · The virus can be reactivated by various disturbances, either
  · physical (injury, U.V, hormones, etc)
  · or psychological (stress, emotional upset - perhaps affecting immune system/hormonal balance)
  · Reactivation of latent virus leads to recurrent disease - virus travels back down sensory nerves to surface of body and replicates,
  · consequently result in the appearance of surface sores.
  


• Generally, primary infection occurs through a break in the membrane of genitals or via the secretion of genitals. Initial infection is usually asymptomatic or may be just a minor local vesicular wound. Local multiplication may results, followed by viraemia (viruses enter the bloodstream and hence have access to the rest of the body) and results in systemic infection. There then follows life-long latent infection with periodic reactivation.
  
• Animation:
  Cellular entry (Receptor Binding)
  RNA Transcription During Productive Infection
  Latency infetion
  HSV DNA Replication

References:
1. Wikipedia, 2008: Genital Infection. Internet: http://en.wikipedia.org/wiki/Herpes_simplex#Genital_infection
2. Wikipedia, 2008: Herpes simple virus. Internet: http://en.wikipedia.org/wiki/Herpes_simplex_virus
3. Dr. Wagner, October 2003: Herpes Simplex Virus Research. Internet: http://darwin.bio.uci.edu/~faculty/wagner/hsv4f.html
4. eMedicineHealth, 26 January, 2007: Genital Herpes. Internet: http://www.emedicinehealth.com/genital_herpes/article_em.htm
5. Derek Wong: Pathogenesis of Herpes Simplex Virus Infection. Internet: http://virology-online.com/viruses/HSV2.htm
6. Virusys: HSV information. Internet: http://www.virusys.com/herpes-simplex-virus-type-1-(hsv%111)/hsv%111-information/hsv-information/

Comments and inquiries are always welcome.

Prepared by Tai Chu Cheng 1061107241

Diagnosis

• The Importance of Diagnosis :
  There is no cure for HSV infections. Once a primary infection of a herpes virus establishes latency, it will persist in the host's cells for life. Antiviral medication is available to treat most herpes virus infections and has been shown to decrease symptomatic recurrences of genital herpes, including the frequency of viral shedding and the transmission of the virus to sexual partners. All patients with suspected genital herpes simplex infection requiring therapy should have confirmation of infection. The Pharmaceutical Benefits Scheme (PBS) requires doctors to provide proof of microbiological confirmation of the diagnosis whenever they prescribe antiviral medication .It is important to note that confirmation of the diagnosis should not delay appropriate therapy.

• Methods of Diagnosis :
  A)Virus Isolation

Figure : Vesicles in a genital herpes lesion.
AHMF: The Diagnosis of Herpes Simplex Virus Infections.

* Virus isolation is most sensitive when lesions are fresh and moist.
* Taking a sample for culture requires breaking a fresh lesion and collecting vesicle fluid and cells rubbed from the base of a lesion.
* It using a rayon-tipped plastic swab to transport the sample to an appropriate viral transport medium.
* Virus isolation as a method of diagnosing herpes infections requires optimal collection and transport conditions, and some pathology laboratories no longer routinely use this method.
* Distinguish between HSV-1 and HSV-2 infection and swabs can be taken from mucocutaneous sites such as endocervical swabs, anogenital swabs, throat and conjunctival swabs. A negative test result does not exclude infection.



B)Direct Antigen Detection



Figure: Immunofluorescence on cell culture.
AHMF: The Diagnosis of Herpes Simplex Virus Infections.


* Direct Antigen detection sample collection requires vesicle fluid and cells rubbed from the base of a lesion.
* It using a rayon-tipped plastic swab.
* Tissue or material from the eye or CFS may also be submitted for rapid antigen detection if herpes encephalitis or ocular infection is suspected.
* This is then transported in an appropriate viral transport medium.
* Direct Antigen detection is a rapid, type specific and sensitive method for detecting HSV.
* Procedure involves a direct immunofluorescence using fluorescein- labelled monoclonal antibodies specific for HSV antigens.
* It has high sensitivity, when vesicles are present, however, sensitivity will fall as lesions heal.
* A negative test result does not exclude infection.



C)PCR



Figure: PCR Roche LightCycler 2.0, Image supplied by Roche Diagnostics Australia Pty Ltd.
AHMF: The Diagnosis of Herpes Simplex Virus Infections.


* Genomic detection by polymerase chain reaction (PCR).
* It is highly sensitive, fully automated and more rapid than viral culture or direct antigen detection.
* PCR allows simultaneous detection and differentiation of HSV-1 and HSV-2.
* It is more sensitive than other detection methods late in infection when the lesions have begun to crust.
* The most commonly used commercial kit is Roche LightCycler HSV 1/2 Detection Kit but the Artus HSV-1/2 PCR kit is also available. A negative test result does not exclude infection.



D)Type Specific Serology
* A blood sample taken for detection of antibodies to HSV.
* HSV antibody testing can reveal acute infection or previous exposure.
* HSV type-specific antibody testing is available using Western blot or enzyme immunoassay.
* Some of the tests only detect HSV-2 infections; others are able to detect both HSV-2 and HSV-1 infections.
* Currently the HSV-1 tests are specific, but have unacceptably low sensitivity.
* HSV-2 specific tests appear to be more sensitive but one widely used test has been shown to have a relatively high rate of false positives.
* Type-specific serology may be useful where culture and PCR are repeatedly negative, to identify infected patients and to help them recognise symptoms and to reduce the chance of transmission to sexual partners.
* HSV type-specific IgM can be detected in acute infection, usually within a few days of clinical lesions, but may take up to 3 weeks to appear.
* Specific IgM response may also appear in severe clinical recurrences. Individual episodes of recurrent genital herpes cannot be reliably diagnosed by serological testing.

References :
1. BMJ Publishing, 2003: Psychosocial impact of serological diagnosis of herpes simplex virus type 2: a qualitative assessment. Internet: http://sti.bmj.com/cgi/content/abstract/79/4/280
2. International Herpes Alliance: Diagnosis and Diagnostics. Internet : http://www.herpesalliance.org/diagnostics.htm
3. AHMF: The Diagnosis of Herpes Simplex Virus Infections. Internet : http://www.ahmf.com.au/health_professionals/guidelines/diagnosis_of_hsv.htm
4. SpringerLink: New strategies for the diagnosis, treatment, and prevention of herpes simplex in contact sports. Internet: http://www.springerlink.com/content/4r51n36q01215134/

Comments and inquiries are always welcome.

Prepared by Teh Yong Jiann 1061105152

Prevention & Treatment

• Prevention:
  The most effective way to avoid transmission of genital herpes is to avoid from sexual contact, or to be in a permanent mutually monogamous relationship with an uninfected partner.
  
  The use of latex condom for both female and male helps in reducing the risk of genital herpes. Nonetheless, the genital area could not be covered completely by the condom. Infected individual who has no symptom with genital herpes also should abstain from sexual contact as the HSV-2 still could be transmitted to uninfected partner.
  
  Furthermore, since the HSV-2 can also be spread by touching another part of the body after touching the sores, one must wash hands with soap and water as soon as possible after touching the sores. Also, do not share towels or clothing with anyone.
  
  An infected pregnant woman is encouraged to have weekly viral cultures of the cervix and outer genitals part as the delivery date approaches. If the viral culture show positive result for herpes, or active lesions are present at delivery, a cesarean delivery is recommended to avoid infecting the baby.
  
  Figure: Male Latex Condom.
  OHSU: Safer Sex Guidelines.
  
  
  Figure: Female Latex Condom.
  Intellx Inc.: Condoms & contraceptives.

• Treatment:
  There is no treatment that can cure herpes. However, antiviral treatment can help in relieve the symptoms. Nucleoside analogs such as aciclovir, valacyclovir and famciclovir are the antiviral drugs which have all been shown to be effective at reducing the severity and length of time of a genital infection.
  
  Besides, suppressive therapy may be helpful for individuals who suffer frequent recurrent outbreaks. This involves taking antiviral medications every day to prevent the virus from reactivating. Suppressive treatment will reduce outbreaks by 85% and reduces viral shedding by more than 90%.
  
  Nonetheless, these antiviral drugs may bring mild side effects like headache and nausea to the patient. Most doctors advise stopping suppressive therapy after a year in order to re-assess the activity of the disease, and to reduce the risk of the virus become resistance to the antiviral drugs. However, some patients need medication through a vein for severe herpes infections that can involve the brain, eyes, and lungs.
  
  In addition, using salt bath to wash the genital area can help in soothes, cleans and dries the sores. Loose cotton underclothes also enhance in minimizes discomfort and allows healing process.
  
  
  Figure: Aciclovir Tablets
  Germes LLC, 1999-2005, Germes Online: Aciclovir Tablets.
  
  
  
  Figure: Famciclovir
  Fair Drugstore, 2007: Famvir(Famciclovir).
  
  
  Figure: Valacyclovir
  NexTag, 2008: Valtrex(Valacyclovir).
  
  

References:
1. Health Beat, January 2008: ILLINOIS DEPARTMENT OF PUBLIC HEALTH, “Genital Herpes”. Internet: http://www.idph.state.il.us/public/hb/hbherpes.htm
2. Australian Herpes Management Forum, 1997-2007: “Genital Herpes”. Internet: http://www.ahmf.com.au/herpes/default.htm
3. MedLine Plus Medical Encyclopedia, March 2008: “Genital Herpes”. Internet: http://www.nlm.nih.gov/medlineplus/ency/article/000857.htm

Comments and inquiries are always welcome.

Prepared by Wong Li Chin 1071113696

Genome Information

• Genome Characteristics:
  Herpes simplex virus type 2 has a genome of double stranded DNA which has been reported to be about 84 to 100 Mdaltons. HSV-2 genomes range in length of 154, 746 bp with base composition of 70.4% G+C content and contain 78 genes.
  
  

  Diagram 1
  MicrobiologyBytes, 2007: Genome.
  

  

  Diagram 2
  Nina Thayer, 2001: HSV-2 Genome and Proteome Properties.

  
  The genome has a unique long (UL) and a unique short (US) region, bounded by inverted repeats (red boxes in the Diagram 1), named LTRa, LTRb and LTRc, the arrangement is shown in Diagram 2. The number of copies of the LTRa repeat may vary. The repeats allow rearrangements of the unique regions and Herpesvirus genomes exist as a mixture of 4 isomers.
  
  Because replication takes place inside the nucleus, HSV-2 can use both the host's transcription machinery and DNA repair enzymes to support a large genome with complex arrays of genes. Herpesvirus genes, like the genes of their eukaryotic hosts, are not arranged in operons and in most cases have individual promoters. However, unlike eukaryotic genes, very few herpesvirus genes are spliced. HSV-2 genomes contain lengthy terminal repeats both direct and inverted. There are six terminal repeat arrangements and understanding how these repeats function in viral success is an interesting part of current research.
  
  




• Genomic Function:
  The genes are characterized as either essential or dispensable for growth in cell culture.
  * Essential genes regulate transcription and are needed to construct the virion.
  * Dispensable genes for the most part (50% of 78 genes) function to enhance the cellular environment for virus production, to defend the virus from the host immune system and to promote cell to cell spread. The large numbers of dispensable genes are in reality required for a productive in vivo infection. It is only in the restricted environment of laboratory cell cultures that they are dispensable.
  



• Virulent Gene:
  
  
  
• Gene Image Map for Human Herpesvirus 2

References:
1. Stanford, 4 March, 1999: Herpesvirus Genome. Internet: http://www.stanford.edu/group/virus/1999/inesicle/genome.html
2. Bernard Roizman, 2001: Herpesvirus Family. Internet: http://stdgen.northwestern.edu/stdgen/bacteria/hhv2/herpes.html
3. American Society for Microbiology, April 1975: Structure and Function of Herpesvirus Genomes. Internet: http://jvi.asm.org/cgi/reprint/15/4/726.pdf
4. MicrobiologyBytes, 11 September, 2007: Herpesviruses. Internet: http://www.microbiologybytes.com/virology/Herpesviruses.html
5. J Virol. 2005 Aug ;79 (16):10498-506 16051842 (P,S,E,B). Internet: http://lib.bioinfo.pl/pmid:16051842.

Comments and inquiries are always welcome.

Prepared by Tan Phit Ling 1071114866

Proposed New Diagnostic Strategy

• By taking B cells (the body's antibody factories) and cracks them open to see if they are starting to produce antibodies. The body produces antibody responses and it is this first wave that seems to be killing the virus in the "immune" patients. This can distinguishe between new first wave acute antibodies and circulating antibodies remaining from a previous infection.
• Screening of latent virus in sacral ganglia at the base of the spine.

References:
1. Biotechnology Investment Today Ltd, 2005:STARTLING NUMBERS OF HIV-RESISTANT SUBJECTS FOUND IN NEW SOUTH AFRICAN TRIAL. Internet: http://www.investinbiotech.com/pressroom_release.php?id=1375

Comments and inquiries are always welcome.

Prepared by Teh Yong Jiann 1061105152

Proposed New Prevention or Treatment

• Vaccines against herpes have been developed but are still considered experimental drugs. Thus, more powerful vaccine should be developed to make our body more resistant to the HSV-2.
  
• We should always maintain a good personal hygiene to reduce the risk.
  
• Washing solution that applies to the genital area, which tends to kill the herpes virus, can be developed too.
  
• Since the nucleoside analogs caused genetic material defect and mutation in the next generation of HSV-2 in an infected individual, a new drug that prevent replication of the virus could be developed to inhibit the virus reproduce in the human body.
  
• Attachment proteins are found on viruses. Since the interaction of the surface lipoproteins or glycoprotein (known as ligand) with host receptor can determine the specificity for host cells, the structural changes or blockage of the ligands or its receptor can be taken into consideration to design a drug to inhibit integration of ligands with host cells, and thus prevent or reduce the genital infection.

References:
1. Health Beat, January 2008: ILLINOIS DEPARTMENT OF PUBLIC HEALTH, “Genital Herpes”. Internet: http://www.idph.state.il.us/public/hb/hbherpes.htm
2. Australian Herpes Management Forum, 1997-2007: “Genital Herpes”. Internet: http://www.ahmf.com.au/herpes/default.htm
3. MedLine Plus Medical Encyclopedia, March 2008: “Genital Herpes”. Internet: http://www.nlm.nih.gov/medlineplus/ency/article/000857.htm

Comments and inquiries are always welcome.

Prepared by Wong Li Chin 1071113696

Proposed Vaccination & Eradication

• Vaccination:

The current goal of a HSV vaccine is to prevent disease but not infection. Because the ability of HSV to escape the Immune Response (IR), it’s difficult for the host cell to effectively clear infection.


Vaccines for HSV are currently undergoing trials. Suggested that these vaccines may protect humans against developing severe primary genital herpes. It may reduce the probability of experiencing recurrent infections and reduce the risk for transmitting HSV virus to a newborn infant.


Proposed that vaccine may prevent HSV disease by mechanism such as inhibits the membrane fusion prior to cellular entry, so the viral capsid won’t get any chance to affect the host cell. Or if it’s affected, we may also reduce the risk of transmitting by replication-impaired vaccine. Or we also reduce the frequency of recurrences with vaccine impaired for establishment of latency by blocking access of the virus to sensory ganglia.


Currently, 2 “Phase III trials” (co-sponsored by the National Institute of Allergy and Infectious Diseases and GlaxoSmithKline) has been conducted. The result had showed that an “investigational” vaccine appears to offer some protection against this disease. However, this vaccine has only been shown to be effective for women who have never been exposed to HSV-1.


The vaccine, called Simplirix®, contains a recombinant form of the HSV-2 envelope glycoprotein, D2, together with a new adjuvant called SBAS4.
In both trials, the vaccine proved to be 73-74% effective against Genital Herpes in HSV-1-negative women, although it did not consistently prevent infection.
But it showed no efficacy in men or in women infected with HSV-1. The study did not determine whether protected women shed virus, and whether they still transmit.

• Eradication:

Until now, there are still no exact cures for this disease. It’s nearly an impossible task to eradicate this disease effectively. Clearances of the viral cell by host cell antibodies (IgM, IgG, etc.) or the immune T cells are rather unrealistic too. Because the virus enters peripheral sensory nerves and migrates along axons to sensory nerve ganglia in the CNS. This allows virus to escape immune response! And once it reaches here, it will remain here undetected for life-long until reactivation to cause recurrent disease.


The eradication of this disease is still a mysterious now. Hypothetically, we can try to block the pathway of HSV-2 to the CNS so it will be carried to the bloodstream and allows the immune cells and antibodies to kill it.

Besides, we may also try to eliminate the virulent genes of HSV-2 and cause the virus unable to replicate, reactive from ganglionic latency, and not able to prevent from immune evasion, therefore eradicate by the immune response of host.

References:
1. eMedicineHealth, 26 January, 2007: Genital Herpes. Internet: http://www.emedicinehealth.com/genital_herpes/article_em.htm
2. Derek Wong: Pathogenesis of Herpes Simplex Virus Infection. Internet: http://virology-online.com/viruses/HSV2.htm
3. Virusys: HSV information. Internet: http://www.virusys.com/herpes-simplex-virus-type-1-(hsv%111)/hsv%111-information/hsv-information/
4. Aurx, 1998: Herpes Treatment. Internet: http://www.aurx.com/herpes2.htm
5. Biovex, 2008: ImmunoVEX. Internet: http://www.biovex.com/immunovex.html

Comments and inquiries are always welcome.

Prepared by Tai Chu Cheng 1061107241

Proposed Genomic Evolution

Genomic Comparison Study:

• HSV-2 to HSV-1 genome comparison
  HSV-2 and HSV-1 share the same overall structure, as well as very high similarity in most genes. The G+C content of the HSV-2 genome is 70.4%, compared with 68.3% for HSV-1. Strains of HSV-1 differ from the strains of HSV-2 at most of their cleavage sites. Only half of the HSV-1 genome is complementary to the HSV-2 genome and that in the homologous regions there is about 15% mismatch in base pairing as judged by the melting temperature of the hybrid. This means that in the homologous regions, one in seven bases differs between HSV-1 and HSV-2.
  
  The BugSpray comparison below shows genome alignment based on similar genes and dramatically illustrates the similarity of gene arrangement between the HSV-1 and HSV-2 genomes. BugSpray draws lines from genes on the top genome, in this case HSV-2, to the gene with the best BLAST hit in the bottom genome, here HSV-1. Green lines indicate pairs of genes that code on the same strand and red lines indicate gene pairs that code on the opposite strand. Clearly there are no rearrangements or reordering of genes between these two viruses. The three red lines show best hits of gamma 34.5, alpha4 and alpha0 to the copy in the inverted repeat, because BugSpray arbitrarily selects only one best hit if there are multiple hits with the same weight. Only Orf-P does not have a BLASTp hit to a gene in the HSV-1 genome.
  
  
  Figure: BUGSPRAY GENOME ALIGNMENT.
  Nina Thayer, 2001: HSV-2 Genome and Proteome Properties.
  
  

• HSV-2 to SA8 genome comparison
  Herpesvirus simian agent 8 (SA8; cercopithecine herpesvirus 2) is a baboon simplexvirus closely related to HSV-2. The genome of SA8 is 150,715 bp long, with an overall G+C content of 76%, the highest among the simplexviruses sequenced so far, compared to HSV-2 in length of 154, 746 bp with base composition of 70.4% G+C content. The genomic arrangement of SA8 is similar to that of other simplexviruses, that is unique long (UL) and unique short (US) regions bordered by 2 sets of inverted repeats, while HSV-2 has 3 sets of inverted repeats.

References:
1. Nina Thayer, 2001: Human Herpesvirus 2 (HSV-2). Internet: http://stdgen.northwestern.edu/stdgen/bacteria/hhv2/hhv2properties.html.
2. American Society for Microbiology, April 1975: Structure and Function of Herpesvirus Genomes. Internet: http://jvi.asm.org/cgi/reprint/15/4/726.pdf
3. Shaun D. Tyler et al., 2004: Complete genome sequence of cercopithecine herpesvirus 2 (SA8) and comparison with other simplexviruses. Internet: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WXR-4DSR13J-2&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=f122e9d1acdb89157dc6240f4e6902c0

Comments and inquiries are always welcome.

Prepared by Tan Phit Ling 1071114866

Special Thanks to...

• Group members:
• Teh Yong Jiann 1061105152
• Tai Chu Cheng 1061107241
• Tan Phit Ling 1071114866
• Wong Li Chin 107111369

• Consultant:
• Mr. Cheong Soon-Fatt

• Researchers of Human Herpesviruses.

• Viewers and people who leave comments at this web site.