Untitled - D Ank Unlimited

Q fever
An acute disease caused by Coxiella burnetii Rickettsia.
Cattle, sheep, goats, and several small marsupials serve as
reservoirs. Ticks are the main vectors. The microorganism
is highly infectious and multiplies readily to produce
clinical infection. The onset is abrupt and accompanied by
headaches, high fever, myalgia, malaise, hepatic dysfunction,
interstitial pneumonitis, and fibrinous exudate. Q fever
may also induce atypical pneumonia, rapidly progressive
pneumonia, or be a coincidental finding to a systemic illness.
The disease has a relatively low mortality. It is treated
successfully with tetracycline and chloramphenicol.
Qa antigens
Class I histocompatibility antigens in mice designated Qa1,
Qa2, and Qa10. They are encoded by genes in the QA region of
the H-2 complex on the telomeric side. Lymphoid cells express
Qa1 and Qa2 antigens, whereas hepatic cells express Q10 antigens.
The Qa represents one of two regions of the Tla complex,
with Tla representing the second region of this complex.
Qa-2 antigen
An antigen encoded by MHC class I genes that is produced
in GPI-linked and soluble secreted forma. It shows little
polymorphism and is tissue-specific. Anti-Qa-2 monoclonal
antibodies are potent T cell activators in the presence of
PMA and cross linking anti-Ig.
Qa locus
A subregion of the murine MHC located on the telomeric
side of the H-2 complex in a 1.5 centiMorgan stretch of
DNA. The Qa region is a part of the Tla complex which
also contains Tla. The Qa region is comprised of 220 kb
that encode for class I MHC α chains that associate noncovalently
with β2 microglobulin. The Qa region is comprised
of eight to ten genes designated Q1, Q2, Q3, etc.
Supernatants
excess Ab
excess Ag
Antibody
precipitated
Antibody-excess
zone
+ + + +
Q
+–
Qa region
Refer to Tla complex.
quantitative gel diffusion test
Estimation of the amount of antibody or antigen by a gel
diffusion method such as single radial diffusion or Laurell
rocket assay.
quantitative precipitin reaction
An immunochemical assay based on the formation of
an antigen–antibody precipitate in serial dilutions of the
reactants, permitting combination of antigen and antibody
in various proportions. The ratio of antibody to antigen is
graded sequentially from one tube to the next. The optimal
proportion of antigen and antibody is present in the tube
that shows the most rapid flocculation and yields the greatest
amount of precipitate. After washing, the precipitate can
be analyzed for protein content through procedures such as
the micro-Kjeldahl analysis to ascertain nitrogen content,
spectrophotometric assay, and other techniques. Heidelberger
and Kendall used the technique extensively, employing
pneumococcus poly sac charide antigen and precipitating
antibody in which nitrogen determinations reflected a
quantitative measure of antibody content.
quaternary structure
Four components that are associated. Two or more folded
polypeptide chains packed into a configuration such as a
tetramer. Quaternary antigenic determinants may be difficult
to demonstrate in such structures as hemoglobin molecules.
quaternary syphilis
The stage of syphilis which follows the tertiary stage. It is
characterized by a necrotizing encephalitis with tissues rich
in spirochetes. End-stage HIV patients who have completely
lost cell-mediated immunity against treponemal antigens
may show this form of syphilis. Although rare in the past,
Equivalence
zone
Antigen Added
Quantitative precipitin reaction.
Antigen-excess
zone
+ + + +
605
Q