Overview of HIV Infection
Mark J. Rosen, James M. Beck in Human Immunodeficiency Virus and the Lung, 1998
Tests for specific fungal antigen (as for cryptococcosis and histoplasmosis) are not available. Serological testing for antibodies is important, but lacks the high sensitivity and specificity of antigen testing. Immunodiffusion for IgM and IgG antibodies is positive in perhaps 75% of cases. Antibody response may be absent in severely immunosuppressed patients, and a negative test does not exclude the diagnosis. The complement fixation test has similar diagnostic usefulness, and it can also be used to follow the progression of the illness and response to therapy. Rising titers are associated with disease progression and falling titers with treatment response. Antibody detection (by complement fixation or other assay) in cerebrospinal fluid is very useful to diagnose meningeal involvement.
Mycoplasma Pneumoniae Pneumonia *
Lourdes R. Laraya-Cuasay, Walter T. Hughes in Interstitial Lung Diseases in Children, 2019
The blood leukocyte and differential counts are generally normal, but erythrocyte sedimentation rate may be slightly increased. Cultures of the throat or sputum on a specific medium may demonstrate M. pneumoniae in 5 to 6 days. The cold hemagglutinin titer is elevated (⩾1:64) in many patients, especially when it is measured 1 week or longer after the onset of symptoms. The cold hemagglutinins are usually the first antibodies detected and, also, the first to disappear. The frequency and the height of the cold hemagglutinin response seem directly related to the severity of pneumonic involvement. These are nonspecific and can develop in patients with other infections. A specific antibody rise in the convalescent phase serum as compared to acute phase serum is diagnostic. Growth-inhibiting antibodies are probably the most specific and persist for a long time after recovery from acute episode.14 Complement fixation tests using extracted lipid antigen and enzyme-linked immunosorbent assay give comparable results and are more practical for clinical laboratories.
The Lymphatic/Immune System and Its Disorders
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss in Understanding Medical Terms, 2020
Immune reactions play a vital role in a number of diagnostic tests. Several infections, including HIV, hepatitis B, and Cytomegalovirus (CMV), are identified by detecting antibodies in the blood. The complement fixation (CF) test is used in the diagnosis of viral diseases by detecting specific antibodies in the patient's serum. The presence of antibodies is assumed to be indicative of infection, and antibody titer (concentration) indicates degree of response or whether the infection is active. Antibodies are detected with immunofluorescence, enzyme-linkedimmunosorbent assay (ELISA), agglutination tests, and iontophoresis. Without the immune response, there would be no antibodies to detect.
An overview of advancement in aptasensors for influenza detection
Published in Expert Review of Molecular Diagnostics, 2022
Varsha Gautam, Ramesh Kumar, Vinod Kumar Jain, Suman Nagpal
Although there are many identification strategies available today, such as rapid influenza diagnostic tests (RIDTs). Enzyme linked immunosorbent assay (ELISA). Double immunodiffusion (DID). Complement fixation test (CF). Hemagglutinin inhibition (HI). Nucleic acid-based assays (NATs), and real time polymerase chain reaction (RT-PCR), but their specificity and time effectiveness still make them less applicable. The flu virus is a ‘form shifter.’ and new plans have to be drawn periodically to improve the vaccine for that year’s influenza outbreak. It has been challenging because of the variability of the influenza strain. Therefore, early identification is the only key available. Present viral diagnosis relies on viral nucleic acid or protein components being selectively identified. Because of specialized laboratory requirements, culture methods can be excluded. Additionally, serological testing is ineffective, requires two sufficient specimens, and takes time. Rapid tests can only detect nucleic acids or a few viral antigens and encourage practical and informative diagnosis. Moreover, RT-PCR is still regarded as costly and time consuming, and ELISA testing does not offer a high degree of sensitivity [14].
Preclinical characterization of dostarlimab, a therapeutic anti-PD-1 antibody with potent activity to enhance immune function in in vitro cellular assays and in vivo animal models
Published in mAbs, 2021
Sujatha Kumar, Srimoyee Ghosh, Geeta Sharma, Zebin Wang, Marilyn R. Kehry, Margaret H. Marino, Tamlyn Y. Neben, Sharon Lu, Shouqi Luo, Simon Roberts, Sridhar Ramaswamy, Hadi Danaee, David Jenkins
To assess the potential for complement fixation by dostarlimab, an ELISA-based C1q binding assay was employed. Dostarlimab or a positive control (MabThera) was coated onto a 96-well polystyrene plate at 8 concentrations: 10, 7.7, 5.9, 4.6, 3.5, 2.7, 2.1, and 1.6 µg/mL. The plate was incubated overnight (2–8°C) and then aspirated. The plate was blocked for 1 hour at room temperature with 1X PBS supplemented with 0.3% BSA and 0.05% Tween 20 before being washed with 10 mM phosphate buffer at pH 7.4 supplemented with 140 mM NaCl, 2.7 mM potassium chloride, and 0.05% Tween 20. Recombinant human C1q (10 µg/mL; Quidel) was added to each well and incubated for 2 hours at room temperature. After incubation, the plate was washed and a sheep anti-human C1q/horseradish peroxidase conjugate (0.5 µg/mL; Abcam, Cat#ab46191) added. The plate was incubated for 1 hour at room temperature, washed, and SuperSignal ELISA Femto Substrate (1:1 mixture of luminol/enhancer and stable peroxide solution; Thermo Fisher Scientific) added to all wells. The plate was read within 1–5 minutes on a luminometer (MS SpectraMax), measuring total light output in relative light units (RLU). Four parameter nonlinear regression analyses were performed on each antibody titration, and EC50 values were calculated.
Multi-functional antibody profiling for malaria vaccine development and evaluation
Published in Expert Review of Vaccines, 2021
D. Herbert Opi, Liriye Kurtovic, Jo-Anne Chan, Jessica L. Horton, Gaoqian Feng, James G. Beeson
During the blood-stage of infection, antibody-mediated complement fixation mediates inhibition of merozoite invasion [121]. In some cases, polyclonal antibodies from semi-immune adults poorly inhibited merozoite invasion when tested alone, and inhibitory activity was only apparent in, or greatly enhanced by, the presence of complement [121]. Antibody-mediated complement activation was also shown to rapidly lead to merozoite lysis in vitro [121]. Further, complement fixation on merozoites was strongly associated with protection against clinical malaria and high-density parasitemia in a longitudinal cohort study of PNG children [65,121]. Interestingly, this level of protection was significantly stronger than that seen for associations with GIA activity, performed in the absence of complement, in the same population [65]. Complement-fixing antibodies were also induced following vaccination with a MSP2-C1 vaccine from a Phase I trial but associations with efficacy remain to be tested [121]. Further, an extensive evaluation of a wide range of merozoite antigens found that complement fixation to a combination of up to three antigens was associated with very high potential protective efficacy compared to that seen with individual antigens [65]. This may be an important consideration for future vaccine design and the inclusion of multi-antigen vaccines.
Related Knowledge Centers
- Antibody
- Elisa
- Immunology
- Polymerase Chain Reaction
- Titer
- Antigen
- Serum
- Complement System
- Red Blood Cell