L11 viruses and their diseases Flashcards
Herpesviruses general
- Family Herpesviridae
- Large dsDNA genomes encoding 100-200 genes, T=16
- All herpesviruses are enveloped icosahedral viruses
- 9 different Herpesviruses that infect mammals:
- Herpes Simplex virus type 1 and 2 (HSV-1/HSV-2)
- Varicella zoster (VZV)
- Human cytomegalovirus (HCMV)
- Epstein Barr virus (EBV)
Alpha subfamily of herpesvirus
HSV-1, HSV-2 and VZV
beta and gamma subfamilies of herpesvirus
- Human cytomegalovirus (HCMV)
- Epstein Barr virus (EBV)
HSV-1 causes
cold sores
Herpes simplex virus
- Involves oral mucosua and lips
- 1st infection can cause herpes gingivostomatitis
- Primary infection no symptoms
- Has latent state in trigeminal ganglia
- Reactivated by stress
- Can cause encephalitis
Herpes simplex virus latent state
- First infection can cause herpes gingivostomatitis; most primary infections don’t produce symptoms
- Following the primary infection, virus persists in a latent state in trigeminal ganglia and is then reactivated by trauma, fatigue, sunlight, emotional stress
Herpes simplex virus type 1
- Herpes labialis, the cold sore, is a recurrence of the first or primary infection
- Previously, most cold sores associated with HSV-1 infection; now by HSV-2
- *Herpetic whitlow *is HSV infection of fingers and thumbs that is very painful
- Most often it is caused by autoinoculation, secondary to genital herpes and health care workers exposed to patients with HSV lesions
Herpes simplex virus type 2
- associated with genital herpes
- Infects epithelial cells of external genitalia, urethra, cervix, rectum and adjacent skin
- Virus transmitted to newborns during delivery (neonatal herpes)
- Can result in blindness and neurological disease in babies. Caesarian delivery recommended for HSV-2-infected pregnant women with active disease
Cycle of infection for Herpse
- Initial infection
- Latency
- Reactivation
- Transmission
Initial infection herpse
After primary infection, viruses remain latent in the sacral plexus of the spinal cord
latency herpes
As is the case for HSV-1, the virus does not replicate, viral genes are not expressed, and host cell does not die.
Reactivation of herpes
Reactivation can occur without symptoms, and host is infectious (also the case with HSV-1).
Transmission of herpse
Virus enters host via break in skin or mucous membranes, especially during sexual contact.
Varicella Zoster Virus (VZV) symptoms and receptor
- VZV causes 2 main syndromes: Varicella (chickenpox) and Zoster (shingles)
- mannose-6-phosphate
¾ VZV infection is acquired by the ____ route
respiratory (airborne)
VZV infection is acquired by the
respiratory route (airborne)
- Dissemination of virus in bloodstream is followed by a rash.
- Vesicles similar to those produced in HSV infection are formed, and form lesions, but unlike the HSV lesions are not infectious
VZV
In some patients, the virus becomes dormant in the____ but can also affect any sensory nerve most commonly the thoracic, trigeminal, cervical, and lumbosacral. The virus can be reactivated to cause ____, in which there is a characteristic distribution of vesicles along the affected dermatome. Usually only one such event in a lifetime, and most often in people who are elderly or ____.
- dorsal root ganglion
- shingles
- immunocompromised
Anti-herpesvirus agents drugs: oral
- Acyclovir
- Valacyclovir
- Famciclovir
Anti-herpesvirus agents drugs: oral
Trigluduridine
Anti-herpesvirus agents drugs: topical agents
- Acyclovir
Human cytomegalovirus general and its infection initiated
- Most people have been infected with HCMV during their life; prevalence is about 80%
- Virus can infect most human cells, and infection is initiated through a nonspecific interaction with heparan sulfate proteoglycans
Human cytomegalovirus in host
- Virus persists in host and is shed for years in saliva, urine, semen, breastmilk and cervical secretions
- Virus interferes with host immune functions including antigen presentation, cytokine production, and natural killer cell activity
Human cytomegalovirus
Certain groups are at risk of more severe disease: a leading cause of illness and death in organ transplant recipients and ________ individuals (especially AIDS patients), also a serious infection of ____
- immunocompromised
- newborns
Epstein Barr virus (EBV)
* causes
* common
* present where
* infects what lining and how
- EBV causes infectious mononucleosis, also known as glandular fever or kissing disease
- Very common infection: 80-90% of people worldwide ¾
- Virus is present in oropharyngeal secretions and therefore is spread by mouth-to-mouth contact or shared drinking glasses ¾
- EBV infects epithelial cells lining the throat. Following replication, new virus particles then infect memory B cells, which rapidly proliferate and take on an atypical appearance that is useful in diagnosis
Epstein Barr virus (EBV) symptoms
Disease is manifested by enlargement of lymph nodes and spleen, sore throat, fever, headache, and general tiredness and weakness
Epstein Barr virus (EBV) also causes Burkitt’s lymphoma where
- EBV also causes Burkitt’s lymphoma in tropical Africa and nasopharyngeal carcinoma in Southeast Asia, East and North Africa, and in Inuit populations ¾
- Burkitt’s lymphoma in Africa is thought to be a consequence of coinfection with malaria, or immunodeficiency ¾
- Burkitt’s lymphoma is seen in patients infected with HIV and who are immunocompromised
Polyoma virus JC
JC virus infection can result in a fatal demyelinating disease of the central nervous system: progressive multifocal leukoencephalopathy (PML) in which oligodendrocytes are destroyed
Human papilloma virus (HPV)
* family
* shape
* spread
- Family Papilliomaviridae ¾
- Nonenveloped icosahedral, small dsDNA viruses ¾
- Infect epithelial cells though micro-abrasions (or other epithelial trauma) causing genital warts and/or cancerous lesions ¾
- Spread by direct contact and by autoinoculation via scratching
- HPV16 and 18 – are responsible for most ____ in women
- HPV 6 and 11 – are responsible for___ and ___ laryngeal
- cervical cancers
- genital warts
- papillomatosis
Human papilloma virus (HPV) stats
- HPV consists of >170 different strains, with > 40 transmitted sexually
- Classified into high risk and low-risk HPV types depending on their oncogenic potential (cause cancer).
- HPV16 and 18 – are responsible for most cervical cancers in women
- HPV 6 and 11 – are responsible for genital warts and laryngeal papillomatosis
- More than 50% of sexually active men and women are infected with HPV
Early Human papilloma virus (HPV) detected by what
Early pre-cancerous changes can be detected in cervical mucosa, via Pap smears; HPV-associated cervical cancer is a leading cause of death in countries where screening Pap smears are not available
Nona-valent human papillomavirus (HPV) vaccine
- 9 HPV strains, including 6, 11, 16 and 18
- School-based National HPV Vaccination Program
- Targets young adolescent
Hepatitis B virus (HBV)
* Infects what
* Transmission
* Clinical features
- HBV infect liver cells (hepatocytes) and causes hepatitis (inflammation of the liver)
- Transmission: Parenteral transmission, Highest concentration of virus found in blood; lower concentrations found in semen, vaginal fluid
- Approximately 50% of acute HBV is acquired sexually Needlestick injury, needle sharing, tattooing, acupuncture
- 30 - 50% of adults – symptomatic acute hepatitis: fatigue, malaise, fever, abdominal pain, icterus (jaundice), pruritus (itching)
- Usually asymptomatic in neonates and young children
HBV transmission
- Parenteral transmission
- Highest concentration of virus found in blood; lower concentrations found in semen, vaginal fluid
- Approximately 50% of acute HBV is acquired sexually
- Needlestick injury, needle sharing, tattooing, acupuncture
Hepatitis B virus (HBV)
* Infection ty[e
* fulminant hepatits
- Most infections are acute and the virus is cleared from the host by immune response
- About 1 in 1000 patients develops fulminant hepatitis and die within 10 days of infection.
- Result of abnormally active destruction of hepatocytes by HB-specific cytotoxic T cells
Hepatitis B virus (HBV) chronic carriers and risks
- Approximately 10% of infections are not cleared and the virus continue to replicate -> chronic carriers (continued HBV viraemia 6 months after infection
- Risk of becoming a carrier is associated with age at infection:
- higher for newborns,
- lower for adults
- Chronic infection is associated with development of cirrhosis (liver damage and scarring) and ultimately, liver cancer (hepatocellular carcinoma)
Hepatitis B virus (HBV) in pregnant women
- HBV infection in a pregnant woman poses a serious risk to her infant at birth
- Perinatal HBV transmission can be prevented by identifying HBV-infected pregnant women and providing hepatitis B immune globulin and hepatitis B vaccine to their infants within 12 hours of birth
- 90% of infants infected vertically go on to chronicity
Hepatitis B virus (HBV)
* antigen
* clearance
* persistence
- Hepatitis B surface antigen (HBsAg) is detectable in blood soon after infection
- Clearance of HBsAg from blood, and appearance of anti-HBs, indicates recovery
- Persistence of HBsAg (> 6 months after infection), lack of anti-HBs, indicates chronic infection – carrier state
