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Pasteurella immunity 559 pathogen-associated molecular pattern (PAMP)
Louis Pasteur at work in his laboratory (Edelfeldt painting).
against anthrax, terming the technique vaccination in honor of
Jenner. He produced a vaccine for rabies by drying the spinal
cords of rabbits and using the material to prepare a series of 14
injections of increasing virulence. The life of a child named
Joseph Meister was saved by this treatment. (See Les Maladies
des Uers a Soie, 1865; Etudes sur le Vin, 1966; Etudes sur la
Bierre, 1876; Oeuvres, 1922–1939).
Pasteurella immunity
Immunity against Pasteurella multocida is mainly humoral
antibody-mediated, yet cell-mediated immune responses
also occur. Naturally acquired immunity to this organism
can develop in unvaccinated cattle and water buffalo even
though the organism is surrounded by a capsule that contributes
to its virulence. Antibody, acting as opsonin, can
render these microorganisms readily susceptible to phagocytosis
by monocytes, macrophages, and polymorphonuclear
neutrophils. Protein toxins from certain strains can
induce the formation of neutralizing antitoxins, but purified
proteins have not been shown to induce protective immunity.
Cattle, buffalo, and poultry vaccinated with bacterins
(formalin-killed organisms in a water-in-oil emulsion) form
antibodies against lipopolysaccharide (LPS). Anti-LPS antibodies
are also associated with naturally acquired immunity.
Not only bacterins but also live attenuated vaccines
have been employed to control P. multocida infections.
patching
The accumulation of membrane receptor proteins cross
linked by antibodies or lectins on a lymphocyte surface
prior to capping. The antigen–antibody complexes are internalized
following capping, permitting antigen processing
and presentation in the context of major histocompatibility
complex (MHC) molecules. Membrane protein redistribution
into patches is passive and does not require energy.
The process depends on the lateral diffusion of membrane
constituents in the plane of the membrane.
patch test
An assay to determine the cause of skin allergy, especially
contact allergic (type IV) hypersensitivity. A small square
1 4
2 5
3
Suspected allergens (1–6)
applied to back under
occlusive dressing
6
Treatment with anti-Ig
Patch test.
(48 hours later)
Eczematous reaction
to allergen 5
Diffuse Patch
Patching.
of cotton, linen, or paper impregnated with the suspected
allergen is applied to the skin for 24 to 48 hours. The test
is read by examining the site 1 to 2 days after applying the
patch. The development of redness (erythema), edema, and
formation of vesicles constitutes a positive test. The impregnation
of tuberculin into a patch was used by Vollmer for
a modified tuberculin test. Multiple chemicals, toxins, and
other allergens may induce allergic contact dermatitis in
exposed members of the population.
paternity testing
Tests performed to ascertain the biological (genetic)
parentage of a child. In the past, they included erythrocyte
enzymes, red blood cell antigens, human leukocyte antigens,
immunoglobulin allotypes, nonimmunoglobulin serum proteins,
and more recently DNA “fingerprinting” (typing). The
demonstration of a genetic marker in a child that is not present
in the father or the mother or in cases where no paternal
antigens are present in the child is enough evidence for direct
exclusion of paternity. Another case of direct exclusion of
paternity is when a child fails to express a gene found in both
the mother and putative father. A child expressing a gene that
only a male can transmit and which the putative father does
not express is evidence for indirect exclusion of paternity.
When a child is homozygous for a marker not present in the
mother or putative father or if the parent is homozygous for a
marker not found in the child, then paternity can be excluded
as an indirect exclusion. Also called identity testing.
pathogen
An agent such as a microorganism that can produce disease
through infection of a host.
pathogen-associated molecular pattern (PAMP)
Repetitive motifs of molecules such as lipopolysaccharide,
peptidoglycan, lipoteichoic acids, and mannans that are
P