Viral Infections
Terry Kotrla, MS, MT(ASCP)BB
Herpes Virus Group
Produce a variety of diseases.
 May result in sub-clinical infections
 May be reactivated under appropriate
conditions.
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Herpes Virus Group
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We will discuss the following:
– Epstein-Barr virus
– Cytomegalovirus
– Herpes simplex virus type I and II
– Varicella-zoster virus
Epstein-Barr Virus (EBV)
Spread through oral transmission
 Cause of Infectious Mononucleosis.
 Other Diseases include:
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– African or Burkitt’s lymphoma
– Nasopharyngeal carcinoma
– B cell lymphoma
Epstein-Barr virus
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African or Burkitt’s Lymphoma
– malignant B-cell neoplasm
– presents as a rapidly growing tumour of the
jaw, face or eye
– grows very quickly, and without treatment
most children die within a few months
– Epstein-Barr virus (EBV) has been strongly
implicated
African or Burkitt’s Lymphoma
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Although BL is a very rapidly growing tumour it
responds well to treatment.
Three pictures: before treatment, 3 days and 6
days after treatment
Nasopharyngeal Carcinoma
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Endemic in South China, Africa, Arctic Eskimos
This is a malignant tumour of the squamous
epithelium of the nasopharynx.
100% contain EBV DNA
Rates are less than 1 per 100,000 in most
populations
Nasopharyngeal carcinomas are found in
association with reactivation of latent EpsteinBarr Virus.
The exact mechanisms of association are
unknown
B-Cell Lymphoma
In most individuals infected with EBV, the virus
is present in the B-cells, which are normally
controlled by T-lymphocytes
 When T-cell deficiency exists, one clone of EBVinfected B-lymphocytes escapes immune
surveillance to become autonomously
proliferating.
 EBV induced B cell lymphomas are most
prevalent in immunocompromised patients.
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Oral Hairy Cell Leukoplakia
Viral infection of the oral cavity.
 Indicator of HIV infection as well as of a
person's lessening or weakening immunity
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Infectious Mononucleosis
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4 to 7 week incubation
Acute self-limiting infection of the RE system
Enlarged lymph nodes in the neck.
Sore throat, fever, rash
Malaise, lethargy, extreme tiredness
Liver and spleen involvement and enlargement
Hematology: High WBC, over 20% atypical
reactive lymphocytes also known as Downey
cells.
Infectious Mononucleosis
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Downey cells may be present
Heterophile Antigens/Antibodies
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Heterophile antigens are a group of
similar antigens found in unrelated
animals, IE, man, sheep, horse, dog cat,
mouse.
 Heterophile antibodies produced
against heterophile antigens of one
species will cross react with others.
Heterophile Antigens/Antibodies
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Forssman antigen is an example of a
heterophile antigen and is found on the
RBCs of many species (guinea pig, dog,
cat, mouse, sheep, fowl, horse)
 Forssman antibodies formed against
Forssman antigens will agglutinate sheep
RBCs.
Paul Bunnell Test
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The original Paul-Bunnell test was a simple titration of sheep cell
agglutinins but this procedure was subsequently modified in order to
distinguish between sheep cell agglutinins formed in IM and the
Forssman-type antibodies found in normal serum, serum sickness
and in certain other conditions.
Tissues rich in Forssman antigen (guinea pig kidney) absorb
Forssman antibodies but do not affect the heterophil antibodies in
IM.
Heterophil antibodies are absorbed by beef cells,
Forssman hapten is a glycolipid usually associated with a protein,
the determinant being largely carbohydrate and therefore heat
stable.
Davidsohn Differential
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The principle behind the Paul-Bunnell-Davidsohn test is that the two
types of sheep agglutinins are distinguished by titrating them before
and after absorption with guinea pig kidney and ox cells.
Patients serum containing antibodies due to IM is added to guinea
pig kidney cells. These antibodies are not absorbed by the kidney
cells. These antibodies then react with Beef (Ox) red blood cells
which causes agglutination and is a positive test for IM.
Patients serum containing Forssman antibodies are added to guinea
pig kidney cells. Antibodies are absorbed by the kidney cells. These
antibodies are then allowed to react with Beef red blood cells which
does not cause agglutination. This is a positive test for Forssman
antigens.
Davidsohn Differential
* To be considered absorbed there must be greater than a three tube
difference between the presumptive titer and the differential titer.
Heterophil Antibody
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Kidney Extract
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Beef Erythrocyte
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Infectious Mono
Not Absorbed
Absorbed
Forssman
Absorbed
Not Absorbed
Serum Sickness
Absorbed
Absorbed
Davidsohn Differential
Advantages
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When properly performed, this
test is specific for Infectious
Mononucleosis and falsepositive results are rare.
Disadvantages
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Davidsohn Differential test is
very time consuming and
burdensome.
Infectious Mono Slide Tests
It was discovered that horse RBCs possess
antigens which react with the antibody
associated with IM.
 Patient serum mixed with horse RBCs,
agglutination is positive.
 Latex agglutination
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Not diagnostic, must look at total clinical
picture.
EBV Specific Antibodies
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EBV specific antibodies may be measured.
Pattern of appearance of EBV antigens.
Most valuable is IgM antibody to viral capsid
antigen (VCA), indicates a current infection (best
marker), lasts about 12 weeks.
Can also detect anti-early antigen (EA) (recent
infection) and anti EB nuclear antigen (EBNA)
(older infection).
ELISA and IFA most commonly used
Cytomegalovirus
Transmission occurs from person to
person.
 Close intimate contact
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– Sexual contact
– Pernatally
– Breast milk
– Organ transplant
– Blood transfusion
CMV Clinical course
Symptoms resemble IM
 In babies may cause life threatening
illness
 Patients with deficient immune systems
 AIDS patients
 Transplant patients
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CMV Immunologic response
Test for CMV antibody using paired serum
samples
 IgM antibodies produced against early and
intermediate-early (IE) CMV antigens, last
for 3 to 4 months.
 IgG appear shortly after and peak at 2 to
3 months.
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CMV Laboratory Diagnosis
Range from culture and cytologic
techniques to DNA probes, PCR and
serologic techniques.
 Detection of antibodies indicator of recent
or active infection.
 Viral cultures
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Microscopic examination of biopsy
specimens
CMV Lab Diagnosis
Detection of CMV antigen in cells using
IFA
 ELISA to detect antibody to CMV
 Other
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– fluorescence assays,
– indirect hemagglutination, and
– latex agglutination
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False positives can occur due to RA and
Epstein-Barr antibodies
Herpes Simplex Virus (HSV)
Most exposed in childhood
 Possesses viral latency – hibernation
 Two types: HSV-1 and HSV-2
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HSV-1
Transmitted from person to person by
saliva or direct contact.
 Cold sores around the mouth most
common.
 Reactivation - may have several episodes
of cold sores during a lifetime
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HSV-1
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Symptoms
– tingling
– Numbness
– Itching
Blister forms, breaks, crusts over
 Reactivation usually caused by stress.
 Conjunctivitis, keratitis and herpetic
whitlow may occur.
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HSV-2
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Results in Herpes genitalis - lesions BELOW the waist.
Transmitted intimate sexual contact or perinatally.
Symptoms
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Pain
Tenderness
Itch
Fever
Headache
Lymphadenopathy
Malaise
HSV-2
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Blisters appear
– Males – penis
– Females – vagina and cervix
– Both – thighs buttocks
Painful, lasts 1-3 weeks
 Virus lies dormant in nearby nerves and
reactivated.
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HSV – 2
Can be fatal in infants
 Woman with active infection needs Csection.
 Infants with localized infections have 70%
mortality rate
 Disseminated neonatal herpes most lethal
form.
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Neonatal Herpes
Laboratory Testing
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Recovery of virus from culture
Direct examination of cells from lesion using IF
or immunoperoxidase stain
DNA probes
ELISA
Latex agglutination
RIA
Indirect IF
Serology NOT very useful
Varicella-Zoster Virus
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Two different manifestations of the same
virus.
– Varicella is the primary infection, causes
chicken pox
– Herpes Zoster causes shingles and is due
to reactivation of the latent virus
Varicella
Fever and vesicular exanthema
 Small, itchy blisters surrounded by
inflamed skin.
 Begins as one or two lesions and spreads.
 Number of lesions vary greatly.
 Blister dries out and forms a scab.
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Chicken Pox
Chicken Pox
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Secondary complications due to infection
most common.
– May also result in pneumonia, encephalitis
and hepatitis.
– Very serious for immunocompromised children
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Vaccine now available
Shingles
Chicken pox – virus goes latent
 Reactivated later in life
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– Weakened immune system
– Aging
– Other factors
Shingles
The typical rash of shingles begins as
redness(erythema) followed by the
appearance of blisters.
 Eruptions follow the path of an infected
nerve.
 The trunk is the area affected in 50% to
60% of cases.
 Skin may be extremely sensitive to touch
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Shingles
Shingles
Shingles
Laboratory Testing
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Important to distinguish VZV from other
infections
– PCR
– Direct Fluorescent Antibody staining
– Viral culture
– IgG and IgM antibody test by ELISA
Rubella Virus
RNA virus with 3 major structural proteins,
E1, E2, and C.
 Incubation 2- 3 weeks
 Highly contagious, spread through
respiratory tract.
 Causes German measles
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Rubella vaccine has resulted in 99%
decline in infections.
Rubella
Congenital rubella
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Congenital Rubella Syndrom most serious.
Fetus infected during first trimester.
result in miscarriage or stillbirth,
live-born serious birth defects or dying.
20% of the children born after such an infection
suffer the severe congenital abnormalities
10-20% of these children die within the first
year of life.
Rubella vaccine contraindicated during
pregnancy.
Rubella Syndrome
Lab testing
IgG and IgM antibodies may form at same
time
 IgM antibodies persist for 4 to 5 weeks,
IgG for life.
 Performed primarily for diagnosis of
acquired infections and to determine
immune status of pregnant patients.
 Some tests detect IgG antibodies, other
IgM.
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Laboratory Testing - Rubella
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Methods include:
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hemagglutination inhibition,
passive hemagglutination,
neutralization,
hemolysis in gel,
complement fixation,
fluorescence immunoassay,
RIA,
ELISA and
latex agglutination.
Rubeola
Single stranded RNA virus best known for
its typical skin rash
 Primarily respiratory infection
 Incubation approximately 10 days, ranges
from 8-13.
 Rash appears at about day 14.
 Airborne precautions
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Rubeola
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Symptoms include
– irritability,
– runny nose,
– eyes that are red and sensitive to light,
– hacking cough, and
– high fever
Rubeola
Fever peaks with the appearance of the rash.
 Rash typically begins on the forehead, then
spreads downward over the face, neck, and
body.
 Rash appears on face first and consists of large
flat red to brown blotches that often flow into
one another
 Rash fades in the same order that it appeared
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Rubeola
Complications
Croup
 bronchitis
 bronchiolitis
 pneumonia
 conjunctivitis
 myocarditis
 Hepatitis
 encephalitis
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Rubeola
More susceptible to ear infections or
pneumonias
 Disease can be severe, with
bronchopneumonia or brain inflammation
 May lead to death in approximately 2 of
every 1,000 cases.
 Most severe in adults
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Measles vaccine
Live attenuated
 DO NOT give to:
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– pregnant women,
– persons with active tuberculosis,
– leukemia,
– lymphoma,
– depressed immune systems.
– People with egg allergies
Measles vaccine
Occasionally causes side effects in persons
with no underlying health problems,
 In about 10% of cases there is a fever
between 5 and 12 days after vaccination,
 In about 5% of cases there is a rash.
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Laboratory Testing
Serology testing provides best means of
confirming a measles diagnosis
 Methods to detect rubeola antibodies
include:
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– hemagglutination inhibition,
– endpoint neutralization,
– complement fixation,
– IFA and
– ELISA.
Laboratory Testing
Diagnosis confirmed by presence of
Rubeola specific IgM antibodies antibodies
 or four-fold rise in IgG antibody titer in
paired samples taken after rash to 10 to
30 days later.
 IgM test highly depended on time of
sample collection with 3-11 days after rash
being optimal.
 IgM false positive due to RA.
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Mumps
Single stranded RNA virus.
 Mumps is transmitted by direct contact
with saliva and discharges from the nose
and throat
 iIncubation 16-18 days.
 Virus can infect many parts of the body,
especially the parotid salivary glands.
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Mumps
Glands usually become increasingly
swollen and painful over a period of 1 to 3
days
 Pain gets worse
 Both the left and right parotid glands may
be affected
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Mumps
Mumps
Mumps - Complications
inflammation and swelling of the brain
 Mumps in adolescent and adult males may
also result in the development of orchitis
 May affect the pancreas or, in females, the
ovaries
 Infection in pregnant women may result in
increased risk for fetal death
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Laboratory Testing
complement fixation
 hemagglutination inhibition
 hemolysis-in-gel
 neutralization assys
 IFA and
 ELISA
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Laboratory Testing
Current or recent infections indicated by presence of
specific IgM antibody in single sample which can be
detected within 5 days of illness.
 Fourfold rise in specific IgG antibody in 2 samples
collected during acute and convalescent phases
 Fluorescent antibody staining for mumps antigens
 Cross-reactivity between antibodies to mumps and
parainfluenza viruses has been reported in tests for IgG,
not a problem since symptoms differ.
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