Chair of Microbiology, Virology, and Immunology

DNA-VIRUSES. ADENOVIRUSES.

HERPESVIRUSES.

ADENOVIRUS (ADV)

DNA viruses first isolated from adenoidal tissue in 1953 Family Adenoviridae Genus Mastadenovirus

There names adenoid degeneration viruses adenoid-pharingeal conjunctival viruses acute respiratory desease agents.

DNA-viruses

Adenoviruses

Non-enveloped DNA virus70-90 nm in size Linear ds DNA genome with core proteins

Adenovirus- Properties

Stable in the environment

Relatively resistant to disinfection (Alcohol,

chlorhexidine, detergents)

Stable in GI tract- can withstand low pH, bile acids and

proteolytic enzymes

Dodecon: Hemagglutinin made up of 12 pentons with their fibers.

ICOSAHEDRAL CAPSIDICOSAHEDRAL CAPSID A polyhedron with 20 equilateral faces and 12 vertices capsomers

ring or knob-shaped units made of 5 or 6 protomers pentamers (pentons) – 5 subunit capsomers hexamers (hexons) – 6 subunit capsomers

Adenoviral proteins

structural

non-structural

According to the time of synthesis in the cell:

early

late

They are differed according to their physical and chemical properties, antigenic specifity. There are capsid and inner proteins. 12 polypeptides (m.w. - 7 500-120 000 D) are identifyded.

ADENOVIRUS - Classification

Subgroups- 6 subgroups (A-F), based on

hemagglutination

Serotypes- 1-49 (human)

Common serotypes:- 1-8, 11, 21, 35, 37, 40

Enteric Adenoviruses belong to subgroup F

Human Adenoviruses Types

Subgenus Serotypes

A 12, 18, 31

B 3, 7, 11, 14, 16, 21, 34, 35

C 1, 2, 5, 6

D 8, 9, 10, 13, 15, 17, 19, 20, 22-30, 32, 33, 36-39, 42-47

E 4

F 40-41

Adenoviruses in the cells

Pathogenesis and Replication

Infects mucoepithelial cells of respiratory, GI

and GU tracts

Enter via epithelium, replicate and spread to

lymphoid tissue

Viremia occurs

Secondary involvement of viscera

Pathogenesis and Replication

Fiber protein determines target cell specificity and attachment

Viral DNA enters host cell nucleus

Early and late phases of replication

Error-prone process

Inclusion bodies in nucleus

Adenovirus-Host Cell Interaction

Type of Interaction Functional Definition Biologic System

Productive infection Complete replication of infectious virions

Cultured human cells

Abortive infection Synthesis of viral gene products without production of infectious virions

Cultured humster or monkey cells

Semipermissive infection

Complete replication with low yields of infectious virions

Cultured rat cells

Malignant transformation

Associated with integration of viral DNA and differential viral and cellular gene expression

Cultured rodent cells

Tumor induction Associated with integration of viral DNA and differential viral and cellular gene expression

Newborn hamsters (mice)

Viral latency Persistant of viral genome Human tonsils

EPIDEMIOLOGYEndemic, epidemic and sporadic infections

Many infections are sub-clinical

Outbreaks:

Military recruits ( 10% basic trainees in 1st week)

swimming pool users, hospitals,

residential institutions, day care settings

TRANSMISSION

Droplets

Fecal-oral route

Direct and through poorly chlorinated

water

Fomites

CLINICAL SYNDROMES

Respiratory

Eye

Genitourinary

Gastrointestinal

Others

Acute Respiratory Disease

FeverTracheobronchitisPneumoniaChildren and adultsEpidemics in military recruitsTypes 4 and 7 most frequently

Adenoviral serotypes and associated diseasesSubgroup Serotype Clinical syndromes

A 31 Infantile gastroenteritis*

B 3, 7, 21 Upper respiratory disease, pneumonia, pharyngoconjunctival fever

C 1, 2, 5 Hemorrhagic cystitis, interstitial nephritis

D 8,19,37 Epidemic keratoconjuctivitis

E 4 Upper respiratory disease, pneumonia

F 40, 41 Infantile gastroenteritis

Remaining serotypes are infrequently isolated or not clearly associated with disease.

* Association with gastroenteritis not as firmly established as with types 40 and 41.

Adenoviral diseases according to patient populationPatient population Clinical syndromes

Infants Pharyngitis, coryza, otitis media

Pneumonia

Diarrhea

Children Upper respiratory disease

Pharyngoconjunctival fever

Diarrhea, mesenteric adenitis

Hemorrhagic cystitis

Adults Acute respiratory disease

Epidemic keratoconjunctivitis

Immunocompromised Pneumonia Gastroenteritis, hepatitisHemorrhagic cystitis, interstitial nephritis Meningoencephalitis

Pharyngoconjunctival fever Headache, fever, malaise

Conjunctivitis and Pharyngitis

Cervical adenopathy, rash and diarrhea also

Main adenovirus types: 3, 4, 7, 14

Epidemics in summer months Contaminated water in swimming pools, fomites

Adenoviral Infections of the eye Epidemic Keratoconjunctivitis (EKC)

Acute follicular conjunctivitis

Pharyngoconjunctival fever

Early conjunctivitis (left) and Bilateral conjunctivitis (right)

Epidemic Keratoconjunctivitis

Incidence in summer Types 8, 19, 37 Outbreaks- in situations of close contact (e.g., schools,

hospitals, camps, nursing homes, workplaces) Spread via droplets and contaminated water

(ophthalmologic solutions and equipment, swimming pools), fomites, hands

EKC-Clinical features

SYMPTOMSSYMPTOMS Pink/red eye Irritation, tearing, foreign-

body sensation Ocular pain Photophobia Fever, malaise Respiratory symptoms

SIGNSSIGNS Conjunctival injection,

ecchymosis Corneal injection (limbus) Diffuse→focal epithelial

keratitis ↓Visual acuity

(subepithelial corneal opacities)

Ipsilateral pre-auricular lymphadenopathy

ADENOVIRAL INFECTIONS -Genitourinary system

Acute hemorrhagic cystitis fever, dysuria, hematuria Types 11, 7, 4, 21, 1 More common in boys

Others Orchitis, nephritis, cervicitis with ulcerated vesicular

lesions, urethritis Types 2, 8, 19, 37

Other Infections due to Adenovirus

Myocarditis

Pericarditis

Meningitis

Rash

Arthritis

Adenovirus infections in Immunocompromised hosts

Disseminated, severe and often fatal infections Due to new infection or reactivation of latent virus Prolonged infections with prolonged viremia and viral

shedding Necrotizing pneumonia, hepatitis, rash, DIC, CNS

involvement

DIAGNOSIS OF ADENOVIRAL INFECTIONS

Variety of clinical specimens depending on clinical

syndrome-NP, conjunctival, stool, urine, tissue,

etc.

Transport in viral transport media

Isolation from pharyngeal/nasal site within 3 days of

symptom onset ( 3 weeks for EKC)

Methods for ADV diagnosisMethods for ADV diagnosis Culture in HeLa, HEK cell lines

Shell vial cell culture

DFA/EIA insensitive except types 40, 41

PCR, nucleic acid probes esp. myocarditis

EM and Immune EM Histology characteristic intranuclear inclusions Serology serum titer corresponding to culture isolate

Diagnosis-Enteric adenoviruses

Isolation requires special media-Graham 293

ELISA for rapid detection is available

Therapy for ADV Infections

Antiviral Cidofovir – limited dataImmunologic Pooled immunoglobulin esp.

pediatric – associated serotypes

Activated T cell infusion –

anecdotal

ADENOVIRUS VACCINE

Oral live attenuated vaccineStrains 4, 7Used in military recruitsManufacture of vaccine was halted in 1996Lapse in immunization was associated with

outbreaks in military recruits

Herpesvirus Family

There are about 80 herpesviruses. Herpes simplex virus 1, Herpes simplex virus 2, Cytomegalovirus, Herpes zoster virus-Varicella virus), Epstein-Barr virus, Herpesvirus 6, Herpesvirus 7. 8

Viruses can be isolated from cows, pigs, hens

All herpesviruses have a core of double-stranded DNA surrounded by a protein coat that exhibits icosahedral symmetry and has 162 capsomeres. The nucleocapsid is surrounded by an envelope. The enveloped form measures 150-200 nm; the "naked" virion, 100 nm. The double-stranded DNA (MW 85-150xlO6) has a wide range of guanine + cytosine content in different herpesviruses, There is little DNA homology among different herpesviruses, except her pes simplex types 1 and 2.

Herpesviruses

Classification Three subfamily:

(Alphaherpesvirinae),

(Betaherpesvirinae),

(Gammaherpesvirinae)

Alphaherpesvirinae: a lot of hosts, short reproductive cycle, effective cells (infected ones) destroying, latent form of existence in ganglia.

Simplexvirus (HSV-1, HSV-2) і Poikilovirus.

Betaherpesvirinae:

Limited spectrum of hosts, reproductive cycle is long.

Infected cells increase their sizes, formation of persistence infections in cell cultures. Virus exist in latent form in limphoreticular cells, secretory glands, kidneys and so on.

Genera:

Cytomegalovirus

Muromegalovirus (mice cytomegalovirus)

Gammaherpesvirinae (EBV, HV-6, 7, 8 MDV):

In vitro viruses replicate in liphoblast cells, cause lytic infection in epithelioid cells fibroblasts.

Viruses have tropism both Т-, and В-lymphocytes, but as a rool infection process is stopped at prelytic stage, so productive cases are absent.

HERPES SIMPLEX (Human Herpesvirus 1 and 2) (Herpes labialis, Herpes genitalis, and many other syndromes).

Infection with herpes simplex virus (herpesvirus hominis) may take several clinical forms. The infection is most often inapparent. The usual clinical man ifestation is a vesicular eruption of the skin or mucous membranes. Infection is sometimes seen as severe keratitis, meningoencephalitis, and a disseminated illness of the newborn.Properties of the Virus. The envelope is derived from the nuclear membrane of the infected cell. It contains lipids, carbohydrate, and protein and is removed by ether treatment. The double-stranded DNA genome is linear (MW 85-106 x 106).

Types 1 and 2 show 50% sequence homology. Treatment with restriction endonucleases yields characteristically different cleavage patterns for type 1 and 2 viruses and even for different strains of each type. This "fingerprinting" of strains allows epidemiologic tracing of a given strain, whereas in the past, the ubiquitousness of herpes simplex virus made such investigations impossible.

Herpesvirus. Several proteins have been identified in the virion, The protein I is associated with the viral capsid; the glycoproteins present in bands 0, 2 -3, 8, and 9 (glycoproteins) are associated with the envelope; and a DNA-binding protein (band number 13) is associated with the internal core.

Chorionallantoic membrane (right) infected with Herpesvirus

The plaques produced by herpesvirus type 2 are larger than the tiny plaques produced by type 1 virus. The virus grows readily and produces plaques in almost any cell culture. Infected cells develop inclusion bodies and then undergo necrosis (cytopathic effect).In Chinese hamster cells, which contain 22 chromosomes, the virus causes breaks in region 7 of chromosome No. 1 and in region 3 of the X chromosome. The Y chromosome is unaffected.

Viral cytopathogenic effect (right)

Differentiation of Types 1 and 2

Herpes simplex virus types 1 and 2 cross-react serologically but may be distinguished by a number of tests: (1) The use of type-specific antiserum prepared by adsorption of the viral antiserum with heterotypically infected cells or by inoculation of rabbits with individual type-specific proteins. (2) The greater temperature sensitivity of type 2 infectivity. (3) Preferential growth in different cell species. (4) Restriction enzyme patterns of virus DNA molecules. (5) Differences in the polypeptides produced by type 1 and type 2.

Oncogenic Properties: After inactivation of their lytic capabilities by ultraviolet irradiation or other means, herpesvirus types 1 and 2 can cause transformation of cultured hamster cells, which may induce tumours when inoculated into newborn hamsters. Viral genetic information can be demonstrated in the tumour cells.

Herpes Simplex Virus

HSV is spread by contact, as the virus is shed in saliva, tears, genital and other secretions.

Primary infection is usually trivial or subclinical in most individuals. It is a disease mainly of very young children ie. those below 5 years.

About 10% of the population acquires HSV infection through the genital route and the risk is concentrated in young adulthood.

Following primary infection, 45% of orally infected individuals and 60% of patients with genital herpes will experience recurrences.

The actual frequency of recurrences varies widely between individuals. The mean number of episodes per year is about 1.6.

Pathogenesis

During the primary infection, HSV spreads locally and a short-lived viraemia occurs, whereby the virus is disseminated in the body. Spread to the to craniospinal ganglia occurs.

The virus then establishes latency in the craniospinal ganglia.

The exact mechanism of latency is not known, it may be true latency where there is no viral replication or viral persistence where there is a low level of viral replication.

Reactivation - It is well known that many triggers can provoke a recurrence. These include physical or psychological stress, infection; especially pneumococcal and meningococcal, fever, irradiation; including sunlight, and menstruation.

Pathogenesis of herpetic infection

Herpesvirus Type 1The clinical entities attributable to herpesvirus type 1 include the following:1. Acute herpetic gingivostomatitis (aphthous stomatitis, Vincent's stomatitis). This is the most common clinical entity caused by primary infections with type 1 herpesvirus. It occurs most frequently in small children (1-3 years of age) and includes extensive vesiculoulcerative lesions of the mucous membranes of the mouth, fever, irritability, and local lymphadenopathy. The incubation period is short (ab out 3-5 days), and the lesions heal in 2-3 weeks.2. Eczema herpeticum (Kaposi's varicelliform eruption). This is a primary infection, usually with herpesvirus type 1, in a person with chronic eczema. In this illness, there may be extensive vesiculation of the skin over much of the body and high fever. In rare instances, the illness may be fatal.

3. Keratoconjunctivitis. The initial infection with herpesvirus may be in the eye, producing severe keratoconjunctivitis. Recurrent lesions of the eye appear as dendritic keratitis or corneal ulcers or as vesicles on the eyelids. With recurrent keratitis, there may be progressive involvement of the corneal stroma, with permanent opacification and blindness.4. Encephalitis. A severe form of encephalitis may be produced by herpesvirus. In adults, the neurologic manifestations suggest a lesion in the temporal lobe. Pleocytosis (chiefly of lymphocytes) is present in the cerebrospinal fluid; however, definite diagnosis during the illness can usually be made only by isolation of the virus (or by demonstrating viral antigens by immunofluorescence) from brain tissue obtained by biopsy or at post-mortem. The disease carries a high mortality rate, and those who survive often have residual neurologic defects.

5. Herpes labialis (cold sores, herpes febrilis). This is the most common recurrent disease produced by type 1. Clusters of localized vesicles occur, usually at the mucocutaneous junction of the lips. The vesicle ruptures, leaving a painful ulcer that heals without scarring. The lesions may recur, repeatedly and at various intervals of time, in the same location. The permanent site of latent herpes simplex virus is the trigeminal ganglion.

Congenital herpes

Herpesvirus Type 2

1. Genital herpes (herpes progenitalis): vesiculoulcerative lesions of the penis of the male or the cervix, vulva, vagina, and perineum of the female. The lesions may be associated with fever, malaise, and inguinal lymphadenopathy. In women with herpesvirus antibodies, only the cervix or vagina may be involved, and the disease may therefore be asymptomatic. Type 2 virus remains latent in lumbar and sacral ganglia. Changing patterns of sexual behaviour are reflected by an increasing number of type 1 virus isolations from genital lesions and of type 2 from facial lesions, presumably as a result of oral-genital sexual activity.

Genital herpes

HV, immune fluorescence test

VARICELLA-ZOSTER VIRUS (Human Herpesvirus 3)

VARICELLA (Chickenpox) ZOSTER (Herpes Zoster, Shingles, Zona)Varicella (chickenpox) is a mild, highly infectious disease, chiefly of children, characterized clinically by a vesicular eruption of the skin and mucous membranes. However, in immunocompromised children the disease may be severe. The causative agent is indistinguishable from the virus of zoster.Zoster (shingles) is a sporadic, incapacitating disease of adults (rare in children) that is characterized by an inflammatory reaction of the posterior nerve roots and ganglia, accompanied by crops of vesicles (like those of varicella) over the skin supplied by the affected sensory nerves.

VARICELLA-ZOSTER VIRUS

Varicella, pathogenesis

Varicella

Herpes zoster pathogenesis

Herpes zoster

VARICELLA-ZOSTER VIRUS, IFT

CYTOMECALOVIRUS (Human Herpesvirus 5) (Cytomegalic

Inclusion Disease)

Cytomegalic inclusion disease is a generalized infection of infants caused by intrauterine or early postnatal infection with the cytomegaloviruses. The disease causes severe congenital anomalies in about 10,000 infants in the USA per year. Cytomegalovirus can be found in the cervix of up to 10% of healthy women.

Cytomegalovirus in the cells

Retina infected by Cytomegalofirus

Cytomegalovirus, IFT

EB HERPESVIRUS (Human Herpesvirus 4)(Infectious Mononucleosis, Burkitt's Lymphoma,

Nasopharyngeal Carcinoma)

EB (Epstein-Barr) virus is the causative agent of infectious mononucleosis and has been associated with Burkitt's lymphoma and nasopharyngeal carcinoma. The virus is an antigenically distinct herpesvirus.Properties of the Virus. Morphology: EB virus is indistinguishable in size and structure from other herpesviruses.Antigenic Properties: EB virus is distinct from all other human herpesviruses. Many different EB virus antigens can be detected by CF, immunodiffusion, or immunofluorescence tests. A lymphocyte-detected membrane antigen (LYDMA) is the earliest-detected virus-determined antigen. EBNA is a complement-fixing nuclear antigen. Early antigen (EA) is formed in the presence of DNA inhibitors and membrane antigen (MA), the neutralizing antigen, is a cell surface antigen. The virus capsid antigen (VCA) is a late antigen representing virions and structural antigen.

EBV

Infectious mononucleosis Angina in patient with infectious mononucleosis

Burkitt's Lymphoma

Nasopharyngeal Carcinoma -

Human Herpesvirus 6 and 7

Pathogenesis. The reservoir and mode of transmission of human herpesvirus 6 and 7 are not well understood at the present time. It should be noted that high prevalence of antibodies early in life would implicate transmission within the home from oropharyngeal secretions; however, this has not yet been documented. Epidemiology. The epidemiology of human herpesvirus 6 and 7 is poorly understood at present. Loss of transplacental antibodies, followed by acquisition of antibodies early in life, implies horizontal transmission within the home environment. By the age of 5, antibodies are present in virtually 100 per cent of the population to both of these viruses. Human herpesvirus 6 exists as type A and B. The type A variant was the original isolate being retrieved from an immunocompromised host. The type B variant is associated with roseola. Some investigators suggest that the genetic differences in these two types warrant distinct names; thus, it is conceivable that the International Herpesvirus Nomenclature Committee may designate these agents as distinct.

Human Herpesvirus 6

Clinical Manifestations. Human herpesvirus 6, 7, 8 have recently been isolated. Human herpes virus 6 (as has human herpes virus 7, but to a lesser extent), has been associated with exanthem subitum, or roseola. This illness is characterized by 3 - 5 days of fever, followed by the appearance of a maculopapular "slapped cheek" rash. In addition, there has been an association between human herpesvirus 6 and rejection of transplanted kidneys, fulminant hepatitis and infections of the central nervous system. Kaposi's Sarcoma Herpesvirus (HHV-8). Recently, a new herpesvirus has been associated with Kaposi's sarcoma and AIDS-related lymphomas of organ cavities. The DNA of this virus is partially homologous to the DNA of Epstein-Barr virus and that of herpesvirus saimiri. This virus immortalizes B lymphocytes. Isolation of the virus has yet to be achieved.

THE ENDTHE END