Positive Reaction In Enzyme-linked Immunosorbent Assay Research Articles

Identification ofTomato ringspot virus(ToRSV) on apple in Iran

Apple (Malus domestica) showing vein yellowing was identified as a natural host of ToRSV in Iran. Mechanical inoculation of enzyme-linked immunosorbent assay (ELISA)-positive samples on Chenopodium spp. and Nicotiana tabacum induced local lesions and systemic infection, respectively. Transmission from the ToRSV-infected tobacco onto apple seedlings resulted in systemic infection and vein yellowing with positive reaction in ELISA. This is the first report of ToRSV on apple in Iran.

A novel enzyme‐linked immunosorbent assay method for the detection of human neutrophil antigen‐2a antibodies

Antibodies to human neutrophil antigen (HNA)-2a are responsible for a number of immune-mediated neutropenia disorders. Although several methods exist for the identification of anti-HNA-2a, all these methods have several limitations. In this study, a solid-phase enzyme-linked immunosorbent assay (ELISA) using recombinant HNA-2a antigen (rHNA-2a) allowing rapid detection of HNA-2a antibodies was developed. Soluble rHNA-2 was generated by transfection of insect cells with CD177 vector. Purified rHNA-2a was immobilized on microtiter wells coated with anti-CD177 and was applied to analyze 10 sera containing HNA-2a antibodies. For the evaluation of the ELISA method, results were compared with the standard assay, MAIGA (monoclonal antibody antigen capture assay) for detection of neutrophil antibodies. The specificity of HNA-2a antibodies in all sera was confirmed by immunoblotting. Sera were then tested simultaneously in ELISA and MAIGA assays. Nine of 10 sera showed positive reactions in ELISA, whereas only 9 of 10 sera reacted in the standard MAIGA assay. All HNA-2a antibodies were detectable in MAIGA when diluted sera were applied. No reaction was observed with different sera containing neutrophil-reactive antibodies (6 anti-HNA-1a, 4 anti-HNA-1b, and 20 anti-HLA Class I and II) in ELISA. All HNA-2a antibodies were detectable in MAIGA when diluted sera were applied. Notably, sera containing anti-proteinase 3 (PR3) from patients with Wegener's granulomatosis reacted in MAIGA. In contrast, this antibody showed no reaction in ELISA with purified rHNA-2a. These results demonstrated that ELISA with rHNA-2a provides a good method for detecting HNA-2a antibodies in human serum. This assay enables to exclude the presence of autoantibody against PR3 in patient's sera, which cannot be differentiated from anti HNA-2a with current serologic methods.

SEROLOGICAL ATTRACTION OF NONTOXIC EGG COMPONENT TO STAPHYLOCOCCAL ANTI‐ENTEROTOXIN

ABSTRACT Raw whole liquid and dried eggs which were purported to contain staphylococcal enterotoxin were analyzed by a number of enzyme‐linked immunosorbent assay (ELISA)‐based methods. The initial evaluation was to establish whether the purported positive ELISA reactions were a result of toxin‐anti‐enterotoxin serological activity. A secondary consideration was to determine whether the putative protein occurred in the yolk and/or white portions of the eggs. A manual polyvalent detection system, manual monovalent ELISA and an automated polyvalent enzyme‐linked fluorescent immunoassay were used to investigate this component in eggs. The ELISA results were instantaneous and showed strong positive reactions (false positives) with the manual and automated polyvalent systems, suggesting nonspecific binding of the egg‐reactive component to one or more staphylococcal enterotoxin antibodies. Further analysis with the monovalent ELISA showed false‐positive reactions when egg extracts were tested separately for enterotoxins A–E. The putative protein from fertilized eggs had caused false‐positive reactions and the eggs did not contain preformed staphylococcal enterotoxin. PRACTICAL APPLICATIONSThe analysis of raw whole liquid and dried eggs for staphylococcal enterotoxin must be performed with circumspection when applying serological systems which use whole antibody, as the resulting positive reaction could be a false‐positive reaction due to a nontoxic component in eggs which reacts with the staphylococcal anti‐enterotoxins.

Doenças exantemáticas e primeira epidemia de dengue ocorrida em Manaus, Amazonas, no período de 1998-1999

In 1998, the FMT/IMT-AM foundation implemented the surveillance system to diagnose acute undifferentiated febrile syndromes, with the objective of active and passive surveillance in Brazilian western Amazonian rainforest to identify and diagnose the etiologic agents of acute fever. The diagnoses were performed using serological tests to detect IgM antibodies by ELISA (Enzyme-linked-immunosorbent assay) CDC/OPAS or using commercial kits. A total of 8,557 serum samples obtained from patients with clinical suspicion of dengue virus were analyzed. ELISA positive reaction to dengue virus was presented by 40% of the serum samples and 26% of the serum samples had positive ELISA reactions to other exanthematous viral diseases, such as rubella, measles, parvovirus, Oropouche virus and Mayaro virus.

Occurrence and Relative Incidence of Viruses Infecting Soybeans in Iran.

A survey was conducted to determine the incidence of Alfalfa mosaic virus (AlMV), Bean common mosaic virus (BCMV), Bean yellow mosaic virus (BYMV), Blackeye cowpea mosaic virus (BlCMV), Cucumber mosaic virus (CMV), Pea enation mosaic virus (PEMV), Peanut mottle virus (PeMoV), Soybean mosaic virus (SMV), Tobacco mosaic virus (TMV), Tobacco ringspot virus (TRSV), Tobacco streak virus (TSV), Tomato ringspot virus (ToRSV), and Tomato spotted wilt virus (TSWV) on soybean (Glycine max) in Iran. Totals of 3,110 random and 1,225 symptomatic leaf samples were collected during the summers of 1999 and 2000 in five provinces of Iran, where commercial soybean is grown, and tested by enzyme-linked immunosorbent assay (ELISA) using specific polyclonal antibodies. Serological diagnoses were confirmed by electron microscopy and host range studies. The highest virus incidence among the surveyed provinces was recorded in Mazandaran (18.6%), followed by Golestan (15.7%), Khuzestan (14.2%), Ardabil (13.9%), and Lorestan (13.5%). Incidence of viruses in decreasing order was SMV (13.3%), TSWV (5.4%), TRSV (4.2%), TSV (4.1%), PEMV (2.9%), BYMV (2.2%), ToRSV (2.1%), AlMV (1.3%), BCMV (0.8%), and CMV (0.6%). Additionally, 1.5% of collected leaf samples had positive reactions in ELISA with antiserum to TMV, indicating the possible infection of soybeans in Iran with a Tobamovirus that is related serologically to TMV. Of 195 leaves from plants showing soybean pod set failure syndrome (PSF) in Mazandaran and Lorestan, only 14 (7.2%) samples had viral infection. No correlation was observed between PSF and presence of the 13 viruses tested, suggesting the involvement of other viruses or factors in this syndrome. To investigate the presence of seed-borne viruses, including SMV, TRSV, ToRSV, and TSV, 7,830 soybean seeds were collected randomly at harvesting time from the major sites of soybean seed production located in Mazandaran and Golestan provinces. According to ELISA analyses of germinated seedlings, 7.1 and 8.9% of the seed samples from Golestan and Mazandaran provinces, respectively, transmitted either SMV, TRSV, ToRSV, or TSV through seed. We also showed that SMV and other seed transmissible viruses, as well as TSWV, usually are the most prevalent viruses in soybean fields in Iran. In this survey, natural occurrence of AlMV, BCMV, BlCMV, BYMV, CMV, PEMV, PeMoV, and TSWV was reported for the first time on soybeans in Iran.

Associations between leptospiral infection and seropositivity in rodents and environmental characteristics in Argentina

Our objective was to look for associations between leptospiral infection in rodents and selected environmental and rodent characteristics in Santa Fe, Argentina. Rodents ( n=214) were trapped alive from January 1998 to December 1999 in three environmental settings. Kidneys from 118 rodents were cultured and serum samples from 201 were processed by enzyme-linked immunosorbent assay (ELISA). Logistic regression was performed with ELISA seropositivity as the dependent variable and rodent characteristics were offered as independent variables. Overall prevalence of positive ELISA reactions was 42% (84/201). In urban areas, leptospiral isolations belonged to the Ballum serogroup; in natural corridors, they belonged to the Icterohaemorragiae serogroup. M. musculus (house mouse) was the most-frequently captured species and the predominant one in urban areas. Most isolates and seropositivity results were obtained on this species. Adults and subadults had higher seroprevalences than juvenile rodents. Oligoryzomys flavescens had higher seroprevalence than Akodon azarae, Mus musculus, Rattus rattus and Rattus norvegicus.

Enzyme-Linked Immunosorbent Assay Used To Analyze Predation ofNilaparvata lugens(Homoptera: Delphacidae) byPirata subpiraticus(Araneae: Lycosidae)

An enzyme-linked immunosorbent assay (ELISA) was developed to detect the consumption of Nilaparvata lugens (Stal) by the lycosid Pirata subpiraticus (Bosenberg et Strand). Antiserum was produced in an ICR mouse using an isolated antigen from the female N. lugens. In cross-reactivity tests against 5 other prey species and 7 spider species found in paddy fields, absorbances for most prey species and spiders were 1.4 female N. lugens gave a positive reaction. The maximum period for the detection of a positive ELISA reaction was 6 h at 27°C after female P. subpiraticus had fed on 3 female N. lugens. P. subpiraticus collected in fields where N. lugens occurred showed a higher frequency of positive reaction in the ELISA than those collected in fields where N. lugens did not occur, suggesting the practical value of this ELISA test.

Serological studies on Corynebacterium pseudotuberculosis infections in goats using enzyme-linked immunosorbent assay.

Corynebacterium pseudotuberculosis was isolated from a goat suffering from caseous lymphadenitis and used for preparation of cell wall antigens and exotoxin for detection of specific antibodies in enzyme-linked immunosorbent assay (ELISA). In immunoblotting sodium dodecyt sulphate (SDS) extracted cell wall antigens revealed molecular weights ranging from 20 to 120 kDa. The raw exotoxin showed molecular weights of 30 and 55 kDa and an inhibition of the haemolysis of a Staphylococcus aureus strain. For validation of the ELISA 109 goats of known clinical status were examined reaching a sensitivity of 96% and a specificity of 76% for this test. No serological reactions showed in 191 goats originating from 11 flocks which never had suffered from caseous lymphadenitis. Using this ELISA test 24 goats originating from flocks suffering from caseous lymphadenitis were examined serologically before and after vaccination with a bacterin. Before vaccination one of the five goats with clinical signs showed no positive reaction in ELISA. After vaccination all 24 animals showed positive reactions. Of a total of 1868 goats sampled in Baden-Wuerttemberg 41 (2.2%) in 22 (10%) flocks showed positive reactions in ELISA.

Association between Helicobacter pylori infection and serum pepsinogen concentrations in gastroduodenal disease.

To investigate the association between Helicobacter pylori infection and serum pepsinogen (PG) 1 and 2 concentrations in various gastroduodenal diseases. Serum PG1 and 2 concentrations and antibodies to H pylori were measured by enzyme linked immunosorbent assay (ELISA); gastric mucosal pH was assessed and urease activity in biopsy tissue was determined. A comparison of the ELISA and urease test results permitted division of the cases into positive, false positive, false negative and negative categories for control, gastritis, and ulcer groups. The gastric mucosal pH and serum PG2 in cases positive for H pylori were significantly increased in ulcer and gastritis cases compared with H pylori negative cases. Similar tendencies were observed for the false positive and false negative categories. A positive ELISA reaction for antibodies and an increased serum PG2 concentration are reliable indicators of H pylori infection.

Comparative Effectiveness of Symptomatology and ELISA For Detecting Two Isolates of Grapevine Leafroll on Graft-inoculated Cabernet franc

An enzyme-linked immunosorbent assay (ELISA) was compared to the standard woody indexing procedure for effectiveness in detecting grapevine leafroll associated virus (GLRaV) 3 and 4 in infected grapevines of cvs. Pinot noir (PN) and Thompson Seedless (TS). Four plants per plot of individual Cabernet franc (CF) indicator plants were each graft-inoculated with buds from 24 vines of PN and TS infected with the GLRaV 3 and 4, respectively. Inoculated indicators were established in the field, observed periodically for symptoms, and assayed by ELISA. All plots showed GLRaV symptoms and positive ELISA reactions by the end of the first full growing season for GLRaV 3 and by the end of the second full growing season for GLRaV 4. Results on an individual plant basis were similar, whereby 92% to 95% of CF inoculated with GLRaV 3 or GLRaV 4 were positive for symptoms and ELISA. ELISA reactions for GLRaV 3 were consistently higher than those for GLRaV 4. Virus transmission was not dependent on growth of inoculated buds. We conclude that ELISA is useful for rapid detection of GLRaV 3 and 4 in dormant wood of source grapevines and in inoculated CF indicators.

Leishmania infantum: Sequence Homology within Minicircle Classes Regardless of Geographical Distance

An enzyme-linked immunosorbent assay (ELISA) is described utilizing the surface glycocalyx crude antigen of adult blood trematodes Learedius learedi, Hapalotrema dorsopora, and Carettacola hawaiiensis, for the detection of circulating antibodies (Ab) in Hawaiian green turtles (Chelonia mydas) naturally infected with the parasites and with or without green turtle fibropapillomatosis (GTFP). A concentration of 10.0 micrograms/ml of antigen was optimal in terms of test specificity and sensitivity. A direct ELISA with anti-reptilian/amphibian phosphatase-labeled IgG identified C. mydas Ab at a dilution of 1/12,800. Utilizing indirect ELISA, it was possible to detect Ab to blood flukes at a dilution of 1/3,200. The gross lesions and histopathology were typical for cardiovascular spirorchidiasis in C. mydas. No significant relationship was found between the size of turtles and the degree of GTFP severity. Forty-seven of 59 (80%) samples, from 5 sites, gave a positive ELISA reaction; 6 of the 47 (13%) specimens gave significantly (P < 0.001) higher absorbance values, with 5 from the same location. All 12 (20%) ELISA-negative turtles originated from 1 site, and the absorbance values of the 41 animals from this location were significantly lower (P < 0.015) when compared with the other 4 sites. The proposed assay is fast, has the feature of visual scoring, and can be used for determination of exposure of C. mydas to the spirorchid trematodes.

Evaluation of a potassium chloride extract of Brucella abortus in an ELISA for detecting Brucella antibodies in bulk tank milk samples from cows

An enzyme-linked immunosorbent assay (ELISA) was developed using as antigen a potassium chloride extract of Brucella abortus strain 1119-3 for detecting Brucella antibodies in bulk tank samples of cow's milk. Three-hundred-thirty-four Milk Ring Test (MRT) suspicions milk samples originating from cattle herds in 13 states and 106 BRT negative milk samples were analyzed. Fifty-four of 334 MRT suspicious milk samples were positive on ELISA; bacteriologic examinations revealed B. abortus field strain was isolated from cows in 15 herds, B. abortus strain 19 was isolated from cows in 16 herds and serologic suspects were reported in 6 of the other 23 herds. Two-hundred-fifty-eight (85.6%) of the 301 MRT suspicious samples were negative on ELISA; field investigations and/or serologic tests on cattle failed to disclose Brucella infection in these herds. Suspicious ELISA reactions were detected in 22 MRT suspicious bulk tank milk samples; serologic suspects were reported in 8 of the 22 herds. No false positive ELISA reactions were detected in the 106 MRT negative bulk tank milk samples collected from dairy herds in 7 states.

Detection by ELISA of Circulating Anti-Blood Fluke (Carettacola, Hapalotrema, and Learedius) Immunoglobulins in Hawaiian Green Turtles (Chelonia mydas)

An enzyme-linked immunosorbent assay (ELISA) is described utilizing the surface glycocalyx crude antigen of adult blood trematodes Learedius learedi, Hapalotrema dorsopora, and Carettacola hawaiiensis, for the detection of circulating antibodies (Ab) in Hawaiian green turtles (Chelonia mydas) naturally infected with the parasites and with or without green turtle fibropapillomatosis (GTFP). A concentration of 10.0 micrograms/ml of antigen was optimal in terms of test specificity and sensitivity. A direct ELISA with anti-reptilian/amphibian phosphatase-labeled IgG identified C. mydas Ab at a dilution of 1/12,800. Utilizing indirect ELISA, it was possible to detect Ab to blood flukes at a dilution of 1/3,200. The gross lesions and histopathology were typical for cardiovascular spirorchidiasis in C. mydas. No significant relationship was found between the size of turtles and the degree of GTFP severity. Forty-seven of 59 (80%) samples, from 5 sites, gave a positive ELISA reaction; 6 of the 47 (13%) specimens gave significantly (P < 0.001) higher absorbance values, with 5 from the same location. All 12 (20%) ELISA-negative turtles originated from 1 site, and the absorbance values of the 41 animals from this location were significantly lower (P < 0.015) when compared with the other 4 sites. The proposed assay is fast, has the feature of visual scoring, and can be used for determination of exposure of C. mydas to the spirorchid trematodes.

Detection of Echinococcus coproantigens by enzyme-linked immunosorbent assay in dogs, dingoes and foxes.

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of Echinococcus coproantigens in fecal samples from dogs, dingoes or foxes infected with either E. granulosus or E. multilocularis. The ELISA was based on protein-A-purified polyclonal antibodies [anti-E. granulosus excretory/secretory (E/S) antigens]. The specificity of the assay as determined in 155 samples derived from carnivores that were free of helminth infection (n = 37) or infected with non-Echinococcus cestodes (n = 76) or with various nematodes (n = 42) was found to be 98% overall. The diagnostic sensitivity was strongly dependent on the homologous worm burden. All 13 samples from foxes harboring greater than 1,000 E. multilocularis worms and 13 of 15 (87%) samples from dogs or dingoes containing greater than 200 E. granulosus worms were ELISA-positive, whereas 34 of 46 samples from foxes harboring less than 1,000 E. multilocularis and 9 of 10 samples from dogs or dingoes bearing less than 200 E. granulosus tested negative. Experimental prepatent infections of dogs with E. granulosus revealed positive ELISA reactions within the prepatent period (10-20 days post-infection) for six animals bearing greater than 1,000 E. granulosus each; a low worm burden (less than 1,000 tapeworms/animal) resulted in ELISA positivity in only 2 of 3 animals at 30 days post-infection at the earliest. All five dogs that had been experimentally infected with E. multilocularis tested positive in the coproantigen ELISA as early as on day 5 post-infection.

Evidence for widespread occurrence of antibodies toEncephalitozoon cuniculi(Microspora) in man provided by ELISA and other serological tests

The enzyme-linked immunosorbent assay (ELISA) was used to survey human sera for antibodies to Encephalitozoon cuniculi using spores obtained from in vitro cultures as antigen. Sera were obtained from patients with tropical diseases, neurological and renal disorders, patients who were HIV positive and those who had been tested for HIV but found to be negative. Sera from inhabitants of the village of Jali, The Gambia and from healthy blood donors were also examined. Numerous sera from all groups except the blood donors gave positive ELISA reactions at dilutions of 1:400. On titration, those with titres of 1:400 were reclassified as negative. Antibody titres of 1:800 and above were considered to be indicative of past or present infections with E. cuniculi. Many of these ELISA seropositives were also positive by IFAT or PAP. When examined by Western blotting of SDS-PAGE protein profiles of E. cuniculi spores, sera from many patients who had a tropical association reacted with the characteristic profiles shown by known positive mouse and rabbit sera. Others in the tropical group showed antibody binding to some but not all of the immunodominant polypeptides and yet others were negative in spite of their reactivity in the ELISA, IFAT or PAP test. Less agreement between ELISA and Western blotting results was obtained with the other groups of patients, although reactivity with one or more of the major polypeptide bands was sometimes seen. Serum from one blood donor, examined by ELISA and Western blotting, was positive. Differences in the methods of antigen preparation and of epitopes recognized by individuals may account for different reactivities in the tests. It is concluded that infections of E. cuniculi are common in the tropics and that reactivations of these infections might be a hazard to AIDS patients.

Detection of Listeria spp. with a monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA)

A monoclonal antibody-based ELISA method for the detection of Listeria spp. was evaluated for its ability to detect this organism in artificially contaminated foodproducts. When the enrichment broth contained 106 cells/ml or more, independent of their physiological state, a positive ELISA reaction was obtained: Some influence of product and/or competitive micro-organisms could be detected. However to assure the successful application of ELISA efficient enrichment procedures are necessary, especially when Listeria spp. are present at low levels.

Evaluation of the Specificity and Sensitivity of Two Commercial Enzyme-Linked Immunosorbent Assay Kits, the Serum Plate Agglutination Test, and the Hemagglutination-Inhibition Test for Antibodies Formed in Response to Mycoplasma gallisepticum

Two commercial enzyme-linked immunosorbent assay (ELISA) kits, seven serum plate agglutination (SPA) antigens, and the hemagglutination-inhibition (HI) test for antibodies to Mycoplasma gallisepticum (MG) were compared for sensitivity and specificity using known MG-positive and MG-negative sera from leghorn chickens. All SPA antigens proved to be highly sensitive when testing MG-positive sera. Laboratory-prepared SPA antigens yielded fewer positive reactions when testing MG-negative sera than commercial SPA antigens. Both MG ELISA kits showed high rates of positive reactions when testing sera from birds given commercial M. synoviae bacterin, fowl coryza (Haemophilus paragallinarum) bacterin, inactivated infectious bursal disease virus vaccine, and to a lesser extent fowl cholera (Pasteurella multocida) bacterin. Immunization with Frey's medium with 12% swine serum-in-oil or Staphylococcus aureus-in-oil resulted in sera which yielded numerous positive ELISA reactions. During the first 1 to 3 weeks, antibodies induced by experimental infection with MG were better detected by the SPA test than by the ELISAs and the HI test, thus confirming the SPA test's importance in Mycoplasma diagnostic serology. The HI test can serve to confirm positive SPA results.

Species-specific extracellular antigen production by ascomycetous yeasts, detected by ELISA.

In this study many yeasts produced heat-stable immunogenic extracellular polysaccharides (EPS). These antigens could be easily detected by competitive enzyme-linked immunosorbent assay (ELISA) or by sandwich ELISA. The antigens of most ascomycetous yeast species tested were almost all species-specific, but those of some basidiomycetous species gave cross reactions with many yeast species, ascomycetes included. Antigens related or similar to those produced by Saccharomyces cerevisiae were detected in culture liquids of 11 strains of the latter, of Kluyveromyces marxianus, of Zygosaccharomyces florentinus and in several samples of beer and wine, but not in culture liquids of 63 other ascomycetous yeast species, 5 Saccharomyces species included. The EPS ELISA of Saccharomyces exiguus gave positive reactions with culture liquids of Candida milleri, C. tropicalis, Hanseniaspora vineae, S. dairensis, S. exiguus, S. unisporus and Saccharomycodes ludwigii. The EPS ELISA of Hansenula wickerhamii gave positive reactions with H. henricii, H. wickerhamii and Pichia pinus, thus showing the relationship of these two genera. The EPS ELISA of Geotrichum candidum appeared to be genus-specific like that of filamentous moulds. In addition to several G. candidum strains, G. fermentans, G. klebahnii responded positively, as well as Candida blankii and C. hydrocarbofumarica. The EPS ELISA of Stephanoascus ciferrii was very specific. Except for 10 strains of this species, only Trichosporon terrestre gave a strong positive reaction in the competitive ELISA.

Evaluation of a diagnostic antigen for the detection of aujeszky's disease virus-infected subunit-vaccinated pigs

An early virus protein complex that is found in the maintenance medium of Aujeszky's disease (AD) virus-infected cells was evaluated as a subunit diagnostic antigen (SUDA) in the enzyme-linked immunosorbent assay (ELISA). This antigen was found in purer form and in larger quantities for up to 12 post-infection in the maintenance medium of AD virus-infected MDBK cell cultures than in the maintenace medium of virus-infected porcine Fallopian tube (PFT) and PK1a cell cultures. The SUDA was shown to be compatible with a lectin-derived subunit vaccine by the absence of positive ELISA reactions for antibody to this antigen in 25 AD virus-free subunit-vaccinated pigs. Following virus challenge, all of 24 surviving vaccinated pigs seroconvertd to SUDA within 10 days. Compatibility with the vaccine was further demonstrated by the absence of positive ELISA reactions for antibody to SUDA in 12 pigs that recieved five or six consecutive vaccine doses at 3-wk intervals. The sensitivity of the ELISA with SUDA was demonstrated by the detection of antibody in virus-infected vaccinated and non-vaccinated pigs for at least 15 and 22 weeks, respectively, following exposure to virus. The SUDA was also economical: it was calculated that 8000–14 000 test could be run with the antigen present in the maintenance medium of one 850 cm 2 plastic tissue culture roller bottle of virus-infected MDBK cells.

Identification of Fetal Bloodstains by Enzyme-Linked Immunosorbent Assay for Human α-Fetoprotein

A rapid and highly sensitive enzyme-linked immunosorbent assay (ELISA) for determination of human alpha-fetoprotein (AFP) using commercially available reagents was devised and applied to identification of fetal bloodstains. When experimentally prepared bloodstains, 1 by 2 mm in area, were submitted to analysis, only fetal bloodstains showed positive reactions in the present ELISA. The reactions did not change significantly when these bloodstains were stored at room temperature for one week. The present ELISA seems to be suitable for forensic science practice.