8010977000 hiv combo test 28 days conclusive

hiv combo test 28 days conclusive:-Although HIV antibody tests are the most appropriate for identifying infection, alternate technologies can contribute to an accurate diagnosis, assist in monitoring the response to therapy, and can be used to effectively predict disease outcome. Viral isolation through viral culture, nucleic acid tests to detect viral RNA, and tests to detect p24 antigen can be used to demonstrate virus or viral components in blood, thereby verifying infection. These methods are highly specific, and a positive result confirms infection. Each has limitations, however, and their use must be tailored to proper testing situations. Tests for viral nucleic acid have recently been introduced, but require sophisticated technology and dedicated, well-trained personnel.

The HIV antigen test is currently used for screening blood for transfusion and is appropriate for use
in several other testing situations. It offers the advantages of simplicity and cost effectiveness
for verifying infection, but is less than perfect.

The p24 antigen assay measures the viral capsid (core) p24 protein in blood that is detectable
earlier than HIV antibody during acute infection. It occurs early after infection due tothe initial
burst of virus replication and is associated with high levels of viremia during which the individual
is highly infectious.

(1) When antibodies to HIV become detectable, however, p24 antigen is often no longer demonstrable, most likely due to antigen-antibody complexing in the blood. When detected, p24 antigen is highly specific for infection. The specificity of the p24 antigen test in detecting HIV infection using PCR as the gold standard was calculated from data using test kits from 2 manufacturers to be 99.9%.

(2) In the same study, the sensitivity following a procedure of neutralization to confirm the presence of p24 antigen (see below) was 100%.

Testing for p24 can be of value in:

(1) detecting early HIV infection,
(2) screening blood,
(3) diagnosing infection in the newborn,
(4) monitoring antiviral therapy. A major limitation is that the test is insensitive when testing
blood, both because low levels of antigen are difficult to detect, and because antigenemia occurs
only transiently during different stages of infection.

(5) In fact, the HIV antigen test is incapable of detecting 75% of blood donors who are infected but
seronegative.

(6)p24 antigen is found in serum in either free form or bound by anti-p24 antibody. Free p24 can be
measured with enzyme immunoassays whereas detection of bound p24 requires pretreatment with an acid to dissociate the complex. Procedures to dissociate antigen-antibody complexes have improved the sensitivity of the p24 test, but antigen remains undetectable in most asymptomaticpatients.(7)
Antibody remains detectable throughout infection, whereas p24 antigen characteristically appears
early and late during infection.