Page 347 - Review of Medical Microbiology and Immunology ( PDFDrive )

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PART IV Clinical Virology
gastrointestinal tract by other enteroviruses can limit repli-
cation of the vaccine virus and reduce protection. (4) It
Coxsackie viruses are named for the town of Coxsackie,
must be kept refrigerated to prevent heat inactivation of the
NY, where they were first isolated.
live virus.
Outbreaks of paralytic polio caused by vaccine-derived
Diseases
poliovirus (VDPV) continue to occur, especially in areas
where there are large numbers of unimmunized people.
These VDPV strains have lost their attenuation by acquir-
viruses cause, for example, herpangina, acute hemorrhagic
ing genes from wild-type enteroviruses by recombination. Coxsackie viruses cause a variety of diseases. Group A
conjunctivitis, and hand-foot-and-mouth disease, whereas
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Outbreaks of VDPV-associated paralytic polio have been
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group B viruses cause pleurodynia, myocarditis, and peri-
contained by campaigns to immunize people in the affected
carditis. Both types cause nonspecific upper respiratory
area with the oral (Sabin) vaccine that interrupts fecal–oral
tract disease (common cold), febrile rashes, and aseptic
transmission.
The duration of immunity is thought to be longer with
section) together cause approximately 90% of cases of viral
the live than with the killed vaccine, but a booster dose is
(aseptic) meningitis.
recommended with both.
The currently approved vaccine schedule consists of
Important Properties
four doses of inactivated vaccine administered at 2 months,

The size and structure of the virion and the nature of the
4 months, 6 to 18 months, and upon entry to school at
4 to 6 years. One booster (lifetime) is recommended for
fication of Coxsackie viruses into group A or B is based on
adults who travel to endemic areas. The use of the inacti-
pathogenicity in mice. Group A viruses cause widespread
vated vaccine should prevent some of the approximately genome RNA are similar to those of poliovirus. The classi-
myositis and flaccid paralysis, which is rapidly fatal,
10 cases per year of vaccine-associated paralytic polio that
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whereas group B viruses cause generalized, less severe
arise from reversion of the attenuated virus in the
lesions of the heart, pancreas, and central nervous system
vaccine.
In 2015, WHO decided to use the bivalent oral vaccine,
A and 6 serotypes of Coxsackie virus B are recognized.
containing types 1 and 3 instead of the trivalent version.
Type 2 was omitted because it has a high rate of reversion
Summary of Replicative Cycle
to virulence and is the main cause of vaccine-derived para-
lytic polio. In addition, WHO decided to use trivalent
Replication is similar to that of poliovirus.
inactivated polio vaccine to induce antibodies against all
three types that will protect against paralytic polio caused,
Transmission & Epidemiology
not only by types 1 and 3, but also by type 2 that is omitted
from the oral vaccine.
oral route, but respiratory aerosols also play a role. They
In the past, some lots of poliovirus vaccines were con-
replicate in the oropharynx and the intestinal tract. Humans
taminated with a papovavirus, SV40 virus, which causes Coxsackie viruses are transmitted primarily by the fecal–
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are the only natural hosts. Coxsackie virus infections occur
sarcomas in rodents. SV40 virus was a “passenger” virus in
worldwide, primarily in the summer and fall.
the monkey kidney cells used to grow the poliovirus for the
vaccine. Fortunately, no increase in cancer occurred in
persons inoculated with the SV40 virus–containing polio
vaccine. However, there is some evidence that SV40 DNA
Group A viruses have a predilection for skin and mucous
can be found in certain human cancers such as non-Hodg-
membranes, whereas group B viruses cause disease in vari-
kin’s lymphoma; the role of SV40 as a cause of cancer in
ous organs such as the heart, pleura, pancreas, and liver.
persons immunized with early versions of the polio vaccine
Both group A and B viruses can affect the meninges and
is unresolved. At present, cell cultures used for vaccine
the motor neurons (anterior horn cells) to cause paralysis.
purposes are carefully screened to exclude the presence of
adventitious viruses.
and gastrointestinal tract, they disseminate via the
Passive immunization with immune serum globulin is
bloodstream.
available for protection of unimmunized individuals known From their original site of replication in the oropharynx
Immunity following infection is provided by type-
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to have been exposed. Passive immunization of newborns
specific IgG antibody.
as a result of passage of maternal IgG antibodies across the
placenta also occurs.
Quarantine of patients with disease is not effective,
Group A–Specific Diseases
because fecal excretion of the virus occurs in infected indi-
Herpangina is characterized by fever, sore throat, and ten-
viduals prior to the onset of symptoms and in those who
der vesicles in the oropharynx. Hand-foot-and-mouth
remain asymptomatic.
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