3. Properties of herpesviruses / structure,,,,,,
•Enveloped double stranded DNA viruses.
•Genome consisits of long and short fragments which may be orientated
in either direction, giving a total of 4 isomers.
•Three subfamilies:
•Alphaherpesviruses - HSV-1, HSV-2, VZV <vericella zoster virus>
•Betaherpesviruses – CMV<cytomegalovirus>, HHV-6<humen herpes virus>, HHV-7
•Gammaherpesviruses – EBV<Epstein barr virus>, HHV-8
•Set up latent or persistent infection following primary infection
•Reactivation are more likely to take place during periods of
immunosuppression
•Both primary infection and reactivation are likely to be more serious in
immunocompromised patients.
4. The herpes simplex virus, also known as
HSV, is an infection that causes herpes.
Herpes can appear in various parts of the
body, most commonly on the genitals or
mouth. There are two types of the herpes
simplex virus. HSV-1, also known as oral
herpes, can cause cold sores and fever
blisters around the mouth and on the face.
HSV-2 is generally responsible for genital
herpes outbreaks
Intoduction
5. IntroductionIntroduction
• Herpes Viruses are a leading cause of humanHerpes Viruses are a leading cause of human
viral diseases, second only to influenza and coldviral diseases, second only to influenza and cold
viruses.viruses.
• Are capable of causing overt disease orAre capable of causing overt disease or
remaining silent for many years only to beremaining silent for many years only to be
reactivated.reactivated.
• NameName HerpesHerpes comes from the Latincomes from the Latin herpesherpes
which, in turn, comes from the Greek wordwhich, in turn, comes from the Greek word
herpeinherpein which means to creep.which means to creep.
6. What Causes Herpes Simplex?
The herpes simplex virus is a contagious virus that can be passed from
person to person through direct contact. Children will often contract
HSV-1 from early contact with an infected adult. They then carry the
virus with them for the rest of their life.
Infection with HSV-1 can happen from general interactions such as eating
from the same utensils, sharing lip balm, or kissing. The virus spreads
more quickly when an infected person is experiencing an outbreak.
Additionally, it is possible to get genital herpes from HSV-1 if the
individual has had cold sores and performed sexual activities during that
time.
HSV-2 is contracted through forms of sexual contact with a person who
has HSV-2. It is estimated that around 20 percent of sexually active adults
within the United States have been infected with HSV-2, according to the
American Academy of Dermatology (AAD). (AAD) While HSV-2 infections
are spread by coming into contact with a herpes sore, the AAD reports that
most people get HSV-1 from an infected person who is asymptomatic, or
does not have sores
7. Who Is At Risk of Developing Herpes Simplex
Infections?
Anyone can be infected with HSV, regardless of age. Your risk is
determined almost entirely based on exposure to the infection.
In cases of sexually transmitted HSV, people are more at risk
when they participate in risky sexual behavior without the use of
protection, such as condoms. Other risk factors for HSV-2
include:
>having multiple sex partners
>being female
>having another sexually transmitted infection (STI)
having a weakened immune system
If a mother is having an outbreak of genital herpes at the time of
childbirth, it can expose the baby to both types of HSV, and may
put them at risk for serious complications.
8. ClassificationClassification
• There are 25 families in theThere are 25 families in the
Herpeotoviridae but only 6 of them infectHerpeotoviridae but only 6 of them infect
man with any regularity.man with any regularity.
Herpes Simplex virus Type 1 (HSV-1)Herpes Simplex virus Type 1 (HSV-1)
Herpes Simplex virus Type 2 (HSV-2)Herpes Simplex virus Type 2 (HSV-2)
Epstein Barr virus (EBV)Epstein Barr virus (EBV)
Cytomegalovirus (CMV)Cytomegalovirus (CMV)
Varicella Zoster virus (VZV)Varicella Zoster virus (VZV)
Human Herpes virus 6Human Herpes virus 6
Human Herpes virus 8Human Herpes virus 8
9. Herpes Simplex VirusHerpes Simplex Virus
(HSV)(HSV)
• These are very large viruses and theirThese are very large viruses and their
genome encodes at least 80 proteins.genome encodes at least 80 proteins.
• Half are not directly involved in the virusHalf are not directly involved in the virus
structure.structure.
• Almost any human cell type can beAlmost any human cell type can be
affected by HSV.affected by HSV.
10.
11. EpidemiologyEpidemiology
• HSV-1 and 2 infections are life-long.HSV-1 and 2 infections are life-long.
• The virus is found in the lesions on theThe virus is found in the lesions on the
skin but can be present in body fluidsskin but can be present in body fluids
including saliva and vaginal secretions.including saliva and vaginal secretions.
• As a result of poor hygiene inAs a result of poor hygiene in
underdeveloped countries, HSV-1underdeveloped countries, HSV-1
antibodies are found in more than 90% ofantibodies are found in more than 90% of
children.children.
12. Epidemiology 2Epidemiology 2
• HSV-2 is normally spread sexually and is foundHSV-2 is normally spread sexually and is found
in the anus, rectum and upper alimentary tractin the anus, rectum and upper alimentary tract
as well as the genital area.as well as the genital area.
• An infant can be infected at birth by a genitally-An infant can be infected at birth by a genitally-
infected mother.infected mother.
• The infant can also be infected inThe infant can also be infected in uteroutero if theif the
mother’s infection spreads.mother’s infection spreads.
• Because of the infant’s underdeveloped immuneBecause of the infant’s underdeveloped immune
system, the resulting infection can be verysystem, the resulting infection can be very
severe and sometimes be deadly.severe and sometimes be deadly.
13. Disease caused by Herpes SimplexDisease caused by Herpes Simplex
VirusesViruses
• Oral Herpes - Cold soresOral Herpes - Cold sores
– Herpetic gingiovostomatitis, the infection,Herpetic gingiovostomatitis, the infection,
often initially on the lips spreads to all parts ofoften initially on the lips spreads to all parts of
the mouth and pharynx.the mouth and pharynx.
14. Disease caused by Herpes SimplexDisease caused by Herpes Simplex
VirusesViruses
• Eczema HerpeticumEczema Herpeticum
– This is found in children with active eczema.This is found in children with active eczema.
– The virus can spread to other organs such asThe virus can spread to other organs such as
the liver and adrenals.the liver and adrenals.
15. Disease caused by Herpes SimplexDisease caused by Herpes Simplex
VirusesViruses
• Genital HerpesGenital Herpes
– Is usually the result of HSV-2.Is usually the result of HSV-2.
– Primary infection is often asymptomatic butPrimary infection is often asymptomatic but
many painful lesions can be developed on themany painful lesions can be developed on the
shaft of the penis and vulva, vagina, cervixshaft of the penis and vulva, vagina, cervix
and perianal region of women.and perianal region of women.
17. Genital HerpesGenital Herpes
• In both sexes, the urethra can be involved.In both sexes, the urethra can be involved.
• Genital Herpes infections can beGenital Herpes infections can be
accompanied by a variety of symptomsaccompanied by a variety of symptoms
including fever, myalgia, glandularincluding fever, myalgia, glandular
inflammation of the groin area (inguinal).inflammation of the groin area (inguinal).
• Some patients have only infrequentSome patients have only infrequent
recurrences but others experiencerecurrences but others experience
recurrences as often as every 14-21 days.recurrences as often as every 14-21 days.
18. Diagnosis of HSVDiagnosis of HSV
InfectionsInfections
• This type of virus is generally diagnosed with a physical exam.This type of virus is generally diagnosed with a physical exam.
Your doctor may check your body for sores and ask you aboutYour doctor may check your body for sores and ask you about
some of your current symptoms. Your doctor may also requestsome of your current symptoms. Your doctor may also request
HSV testing, also known as a herpes culture, to confirm theHSV testing, also known as a herpes culture, to confirm the
diagnosis if you have sores on your genitals. During this test,diagnosis if you have sores on your genitals. During this test,
your doctor will take a swab sample of fluid from the sore andyour doctor will take a swab sample of fluid from the sore and
then send it to a laboratory for testing.then send it to a laboratory for testing.
• Blood tests looking for antibodies to HSV-1 and HSV-2 mayBlood tests looking for antibodies to HSV-1 and HSV-2 may
also be used to diagnose these infections. This is especiallyalso be used to diagnose these infections. This is especially
helpful when there are no sores present.helpful when there are no sores present.
20. Diagnosis of HSVDiagnosis of HSV
InfectionsInfections
• The cells can also be stained with specificThe cells can also be stained with specific
antibodies in an immunofluorescence test.antibodies in an immunofluorescence test.
• It can also be detected by viral DNA by inIt can also be detected by viral DNA by in
situ hybridization.situ hybridization.
• Type-specific antibodies can distinguishType-specific antibodies can distinguish
between HSV-1 and HSV-2.between HSV-1 and HSV-2.
21. TreatmentTreatment
• AcyclovirAcyclovir
– A Safe and extremely well-tolerated drug.A Safe and extremely well-tolerated drug.
– More than 35 million patients have beenMore than 35 million patients have been
consistent and reassuring.consistent and reassuring.
– Some authorities have proposed makingSome authorities have proposed making
acyclovir available as a non-prescription drug.acyclovir available as a non-prescription drug.
– Adverse effects, usually mild, include nausea,Adverse effects, usually mild, include nausea,
vomiting, rash and headache.vomiting, rash and headache.
22. TreatmentTreatment
• ValacyclovirValacyclovir
– New antiviral agentNew antiviral agent
– Is the 1-valine ester prodrug of acyclovir.Is the 1-valine ester prodrug of acyclovir.
– It has an oral bioavailability three to five timesIt has an oral bioavailability three to five times
greater than that of acyclovir.greater than that of acyclovir.
– Several large trials have shown that it is safeSeveral large trials have shown that it is safe
and well tolerated.and well tolerated.
23. TreatmentTreatment
• FamciclovirFamciclovir
– Another new antiviral medicationAnother new antiviral medication
– Is the oral form of penciclovir, a purine analogIs the oral form of penciclovir, a purine analog
similar to acyclovir.similar to acyclovir.
– Oral bioavailability is 77% and the drug isOral bioavailability is 77% and the drug is
quickly converted to its active form.quickly converted to its active form.
– Famciclovir’s intracellular half-life is 10 timesFamciclovir’s intracellular half-life is 10 times
longer than acyclovir’s.longer than acyclovir’s.
– Dosing less frequently than twice daily is notDosing less frequently than twice daily is not
recommended.recommended.
24. Preventing the Spread of Herpes Simplex Infections
Although there is no cure for herpes, you can take precautionary measures to
avoid becoming infected, or to prevent spreading HSV to another person.
If you are experiencing an outbreak of HSV-1, try to avoid direct physical
contact with other people. Do not share any items that can pass the virus
around, such as cups, towels, silverware, clothing, makeup, or lip balm.
Doctors also recommend that infected individuals should not participate in oral
sex, kissing, or any other type of sexual activity, during an outbreak.
Additionally, if your hands have come into contact with your sores, you should
wash them thoroughly and apply medication with cotton swabs to reduce
contact.
Individuals with HSV-2 should avoid any type of sexual activity with other
people during an outbreak. If the individual is not experiencing symptoms but
has previously been diagnosed with the virus, a condom should be used during
intercourse. Although a condom may be used, it may still be possible to pass
herpes to your partner from uncovered skin. Women who are pregnant and
infected may have to take medicine to prevent the virus from infecting their
unborn babies.
