Microbiology and Immunology

Cowpox WORLD OF MICROBIOLOGY AND IMMUNOLOGY

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A bacterial suspension is best analyzed in the Coulter

counter when the suspension has been thoroughly shaken

beforehand. This step disperses the bacteria. Most bacteria

tend to aggregate together in a suspension. If not dispersed, a

clump of bacteria passing through the orifice of the counter

could be counted as a single bacterium. This would produce an

underestimate of the number of bacteria in the suspension.

The Coulter counter has been used for many applica-

tions, both biological and nonbiological. In the 1970s, the

device was reconfigured to incorporate a laser beam. This

allowed the use of fluorescent labeled monoclonal antibodies

to detect specific types of cells (e.g., cancer cells) or to detect

a specific species of bacteria. This refinement of the Coulter

counter is now known as flow cytometry.

See alsoBacterial growth and division; Laboratory techniques

in microbiology

CCowpoxOWPOX

Cowpox refers to a disease that is caused by the cowpox or

catpox virus. The virus is a member of the orthopoxvirus fam-

ily. Other virusesin this family include the smallpoxand vac-

cinia viruses. Cowpox is a rare disease, and is mostly

noteworthy as the basis of the formulation, over 200 years ago,

of an injection by Edward Jennerthat proved successful in

curing smallpox.

The use of cowpox virus as a means of combating

smallpox, which is a much more threatening disease to

humans, has remained popular since the time of Jenner.

Once a relatively common malady in humans, cowpox

is now confined mostly to small mammals in Europe and the

United Kingdom. The last recorded case of a cow with cow-

pox was in the United Kingdom in 1978. Occasionally the dis-

ease is transmitted from these sources to human. But this is

very rare. Indeed, only some 60 cases of human cowpox have

been reported in the medical literature.

The natural reservoir for the cowpox virus is believed to

be small woodland animals, such as voles and wood mice.

Cats and cows, which can harbor the virus, are thought to be

an accidental host, perhaps because of their contact with the

voles or mice.

The cowpox virus, similar to the other orthopoxvirus, is

best seen using the electron microscopictechnique of negative

staining. This technique reveals surface details. The cowpox

virus is slightly oval in shape and has a very ridged-appearing

surface.

Human infection with the cowpox virus is thought to

require direct contact with an infected animal. The virus gains

entry to the bloodstream through an open cut. In centuries past,

farmers regularly exposed to dairy cattle could acquire the dis-

ease from hand milking the cows, for example. Cowpox is typ-

ically evident as pus-filled sores on the hands and face that

subsequently turn black before fading away. While present, the

lesions are extremely painful. There can be scars left at the site

of the infection. In rare instances, the virus can become more

widely disseminated through the body, resulting in death.

Both males and females are equally as likely to acquire

cowpox. Similarly, there no racial group is any more suscepti-

ble to infection. There is a predilection towards acquiring the

infection in youth less than 18 years of age. This may be

because of a closer contact with animals such as cats by this age

group, or because of lack of administration of smallpox vaccine.

Treatment for cowpox tends to be ensuring that the

patient is as comfortable as possible while waiting for the

infection to run its course. Sometimes, a physician may wish

to drain the pus from the skin sores to prevent the spread of the

infection further over the surface of the skin. In cases where

symptoms are more severe, an immune globulin known as

antivaccinia gamaglobulin may be used. This immunoglobulin

is reactive against all viruses of the orthopoxvirus family. The

use of this treatment needs to be evaluated carefully, as there

can be side effects such as kidney damage. Antibodies to the

vaccinia virus may also be injected into a patient, as these

antibodies also confer protection against cowpox.

See alsoVaccination; Virology; Zoonoses

COXIELLA BURNETII•seeQ FEVER

CRANBERRY JUICE AS AN ANTI-ADHE-

SION METHOD•seeANTI-ADHESION METHODS

CREUTZFELDT-JAKOB DISEASE(CJD)•

seeBSE ANDCJD DISEASE

CCrick, Francis RICK, FRANCIS(1916- )

English molecular biologist

Francis Crick is one half of the famous pair of molecular biol-

ogists who unraveled the mystery of the structure of DNA

(deoxyribonucleic acid), the carrier of genetic information,

thus ushering in the modern era of molecular biology. Since

this fundamental discovery, Crick has made significant contri-

butions to the understanding of the genetic codeand gene

action, as well as the understanding of molecular neurobiol-

ogy. In Horace Judson’s book The Eighth Day of Creation,

Nobel laureate Jacques Lucien Monodis quoted as saying,

“No one man created molecular biology. But Francis Crick

dominates intellectually the whole field. He knows the most

and understands the most.” Crick shared the Nobel Prize in

medicine in 1962 with James Watsonand Maurice Wilkinsfor

the elucidation of the structure of DNA.

The eldest of two sons, Francis Harry Compton Crick

was born to Harry Crick and Anne Elizabeth Wilkins in

Northampton, England. His father and uncle ran a shoe and

boot factory. Crick attended grammar school in Northampton,

and was an enthusiastic experimental scientist at an early age,

producing the customary number of youthful chemical explo-

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