The enzyme-linked Immunosorbent Assay (ELISA) is the gold standard clinical diagnostic tool for the detection and quantification of protein biomarkers. However, conventional ELISA tests have drawbacks in their requirement of time, expensive equipment and expertise for operation. Hence, for the purpose of rapid, high throughput screening and point-of-care diagnosis, researchers are miniaturizing sandwich ELISA procedures on Lab-on-a-Chip and Lab-on-Compact Disc (LOCD) platforms. This paper presents a novel integrated device to detect and interpret the ELISA test results on a LOCD platform. The system applies absorption spectrophotometry to measure the absorbance (optical density) of the sample using a monochromatic light source and optical sensor. The device performs automated analysis of the results and presents absorbance values and diagnostic test results via a graphical display or via Bluetooth to a smartphone platform which also acts as controller of the device. The efficacy of the device was evaluated by performing dengue antibody IgG ELISA on 64 hospitalized patients suspected of dengue. The results demonstrate high accuracy of the device, with 95% sensitivity and 100% specificity in detection when compared with gold standard commercial ELISA microplate readers. This sensor platform represents a significant step towards establishing ELISA as a rapid, inexpensive and automatic testing method for the purpose of point-of-care-testing (POCT) in resource-limited settings.
The low potency of cobra antivenom has been an area of concern in immunotherapy for cobra envenomation. This study sought to investigate factors limiting the neutralizing potency of cobra antivenom, using a murine model. We examined the immunological reactivity and neutralizing potency of a Thai polyvalent antivenom against the principal toxins of Naja sumatrana (Equatorial spitting cobra) venom and two related Asiatic cobra venom α-neurotoxins. The antivenom possesses moderate neutralizing potency against phospholipases A2 (P, potency of 0.98mg/mL) and moderately weak neutralizing potency against long-chain α-neurotoxins (0.26-0.42mg/mL) but was only weakly effective in neutralizing the short-chain α-neurotoxins and cardiotoxins (0.05-0.08mg/mL). The poor neutralizing potency of the antivenom on the low molecular mass short-chain neurotoxins and cardiotoxins is presumably the main limiting factor of the efficacy of the cobra antivenom. Our results also showed that phospholipase A2, which exhibited the highest ELISA reactivity and avidity, was most effectively neutralized, whereas N. sumatrana short-chain neurotoxin, which exhibited the lowest ELISA reactivity and avidity, was least effectively neutralized by the antivenom. These observations suggest that low immunoreactivity (low ELISA reactivity and avidity) is one of the reasons for poor neutralization of the cobra venom low molecular mass toxins. Nevertheless, the overall results show that there is a lack of congruence between the immunological reactivity of the toxins toward antivenom and the effectiveness of toxin neutralization by the antivenom, indicating that there are other factors that also contribute to the weak neutralization capacity of the antivenom. Several suggestions have been put forward to overcome the low efficacy of the cobra antivenom. The use of a 'proper-mix' formulation of cobra venoms as immunogen, whereby the immunogen mixture used for hyperimmunization contains a mix of various types of α-neurotoxins and cardiotoxins in sufficient amount, may also help to improve the efficacy and broaden the neutralization spectrum of the antivenom.
Evaluation of binding between analytes and its relevant ligands on surface plasmon resonance (SPR) biosensor is of considerable importance for accurate determination and screening of an interference in immunosensors. Dengue virus serotype 2 was used as a case study in this investigation. This research work compares and interprets the results obtained from analytical analysis with the experimental ones. Both the theoretical calculations and experimental results are verified with one sample from each category of dengue serotypes 2 (low, mid, and high positive), which have been examined in the database of established laboratorial diagnosis. In order to perform this investigation, the SPR angle variations are calculated, analyzed, and then validated via experimental SPR angle variations. Accordingly, the error ratios of 5.35, 6.54, and 3.72% were obtained for the low-, mid-, and high-positive-specific immune globulins of patient serums, respectively. In addition, the magnetic fields of the biosensor are numerically simulated to show the effect of different binding mediums.
Nipah virus is a newly discovered paramyxovirus transmitted directly from pigs to humans. During a large encephalitis outbreak in Malaysia and Singapore in 1998-9, most patients presented acutely. A 12 year old child is described who developed encephalitis 4 months after exposure to the virus. She was diagnosed by a new indirect IgG enzyme linked immunosorbent assay (ELISA), which is also described. The late presentation and IgG subclass responses had similarities to subacute sclerosing panencephalitis. Nipah virus should be considered in patients with encephalitis even months after their possible exposure.
Hepatitis B surface antigen can be serologically defined as ayw1, ayw2, ayw3, ayw4, ayr, adw2, adw4 and adrq+ or adrq-. A study of common HBsAg subtypes in 44 HBsAg reactive sera in University Hospital was conducted using a solid-phase sandwich EIA. Eleven samples were found not typable and among the 33 typable HBsAg reactive sera, 3 HBsAg subtypes: adw, adr and ayw were identified. Subtype adw was found in 66.7% (22/33) of the typable HBsAg reactive sera; 24.2% (8/33) was of subtype adr and 6.0% (2/33) of subtype ayw. One sample was found to be reactive to both adw and adr. HBsAg subtype adw was found more commonly in Chinese but among the Malays, HBsAg subtype adr appeared to predominate. However, the small sample size precludes firm conclusions on the predominant subtype among the Malays.
Matched MeSH terms: Hepatitis B Antibodies/analysis*
Thirty-six patients with lupus nephritis (LN) attending the Nephrology Clinic, Hospital Kuala Lumpur were studied for the prevalence of anticardiolipin antibody (ACA) isotypes (IgG and IgM) and other associated antibodies, antinuclear antibody (ANA) and anti-ds DNA antibody and to determine the possible association between serological and clinical parameters. The study population consisted of 20 (55.6%) Malays, 15 (41.7%) Chinese and 1 (2.8%) Indian with a mean age of 31.4 +/- 11.3 years, range 14 to 60 years. The female to male ratio was 11:1. The average time between diagnosis and blood sampling was 4.4 years (range 0.25 to 15 years). Increased ACA levels were found in 20 (55.6%) patients where raised IgG ACA and IgM ACA were observed in 20 (55.6%) and 2 (5.6%) cases respectively. ANA and anti-ds DNA antibodies were detected in 22 (61.1%) and 4 (11.1%) individuals respectively, with the majority (82%) showing a speckled pattern of nuclear staining. However, neither the IgM ACA nor IgG ACA showed any significant association with thrombosis or any other clinical parametres. Our preliminary study indicates that ACA is a frequent finding in lupus nephritis and that the IgG isotype is more prevalent.
Study site: nephrology Clinic, Hospital Kuala Lumpu
This study examined the prevalence of hepatitis B and C markers in 55 paediatric oncology patients who had completed treatment at the Hospital Universiti Sains Malaysia in Kota Baru. All these children had received blood products and had been treated between 1985-1996. Forty seven per cent of patients were positive for hepatitis B or C. Twenty nine per cent were positive for hepatitis C and twenty two per cent were HBsAg positive. Two children were positive for both and none were HIV positive. Four children had an elevated ALT level and one child had jaundice and hepatomegaly. Some children were marker-positive despite immunization and screening of blood.
Hema-Strip HIV-1/2 is a one-step rapid test for the detection of anti-HIV-1/2 antibodies in whole blood. The test requires no expensive equipment and the results are available within 10-15 min. Using 72 known HIV-1 positive samples and 780 high-risk prisoners, the sensitivity and specificity of Hema-Strip HIV-1/2 was found to be comparable to microparticle enzyme immunoassay (MEIA). The data also indicated that Hema-Strip HIV-1/2 is an effective alternate testing system to conventional ELISA where the use of ELISA is not suitable and the result of the HIV testing is needed urgently.
The aim of this study was to determine if knowledge of both the serum HCV RNA and serum anti core IgM antibody status enabled one to predict the histological severity in chronic hepatitis C. We studied 45 female patients with chronic hepatitis C infection. The presence or absence of IgM antibodies to HCV and HCV RNA by PCR in each patient's serum was determined. Liver biopsies performed were scored according to a modified Desmet's histological activity index. Negative HCV RNA patients had least histological change. HCV RNA positive patients who were also IgM antibody positive had lower scores than their IgM negative counterparts. The grade of histological severity is more accurately predictable from knowledge of both the HCV RNA and IgM anti HCV status of the patient.
Matched MeSH terms: Hepatitis C Antibodies/analysis*
We studied the prevalence of antinuclear (ANA), anti-double stranded DNA (dsDNA), anti-Sm and anti-RNP antibodies in a group of 93 blood donors (age range: 18-58 years). Antinuclear and anti-ds DNA antibodies were detected by immunofluorescence (IF) using HEp2 cells and Crithidia luciliae as substrates, respectively, while anti-Sm and anti-RNP antibodies were assayed by ELISA. ANA was found in 6.5% while anti-dsDNA antibodies were not detected in any of the subjects. The 98th percentile was used as cut off where values greater than 0.651 for anti-Sm and 0.601 for anti-RNP antibodies were taken to be positive. This gives a frequency of 1.1% for both antibodies. There was no significant association of antibody positivity with sex or race. We conclude that certain autoantibodies are present in low titres in the normal Malaysian Individuals, at a different frequency compared to other studies probably due to genetic, ethic or environmental factors.
Sixteen isolations of bluetongue virus (BTV) were made from the heparinised bloods of 4 groups of cattle and sheep in Peninsular Malaysia. These viruses were typed as BTV serotypes 1, 2, 3, 9, 16 and 23. Multiple serotypes of BTV are apparently endemic in Malaysia and in other countries in the region.
Two of the three buffaloes immunized with a non-adjuvanted broth bacterin were found to be protected against experimental challenge at 6 weeks but not at 3 months post-challenge. Similarly all buffaloes (4/4) immunized with alum-precipitated vaccine were protected at 6 months but only 1 of the 2 vaccinated animals were protected at 12 months post-immunization. On the other hand, buffaloes immunized with an oil adjuvant and a double emulsion vaccine were completely protected at 12 months post-immunization. Statistically significant differences between immunized versus non-immune animals became evident at 3 months post-immunization, although analysis of cumulative antibody titres of pre-challenge sera of vaccinated buffaloes surviving versus those succumbing to experimental challenge revealed significant by higher antibody titres in the former as compared to the latter group. These results suggested that there was a relationship between ELISA antibody titres and active protection in buffaloes. There also appeared to be a relationship between cutaneous delayed-type hypersensitivity and active protection in buffaloes. Preliminary analysis of the antibody isotype distribution in the pre-challenge sera of 2 buffaloes vaccinated with the oil adjuvant vaccine revealed predominance of IgG1 and IgG2 subclasses whose role in protection against haemorrhagic septicaemia was not eludicated.
Sera from 420 military personnel serving in Sabah and Sarawk, Malaysia, were tested for antibodies to Pseudomonas pseudomallei exotoxin and whole cell antigens by enzyme-linked immunosorbent assay procedure (ELISA). Data showed that 54.4% of serum samples were positive for antibodies to P. pseudomallei exotoxin and 65.7% were positive for antibodies to the whole cell antigens. Samples gave much lower titers for anti-exotoxin antibodies compared to titers against crude whole cell antigens. The incidence of antibody to exotoxin was highest in the age groups ranging from 26 to 32 years, where the positive rates were higher than 40% and 30% for military personnel serving in Sarawak and Sabah, respectively.
Rapid diagnosis of dengue infection is essential to patient management and disease control. The development of a rapid (5 min) immunochromatographic test and a 2 h commercial capture enzyme linked immunosorbent assay (ELISA) for anti-dengue IgM and IgG antibodies may lead to more rapid and accurate testing in peripheral health settings and diagnostic laboratories.
Anti-HCV antibody was detected in 1.9% of the blood donors in University Hospital. Among the risk groups, 33.3% of the patients with post-transfusion hepatitis were tested positive for anti-HCV antibody. The anti-HCV antibody was detected in 30% of the IDU. Haemodialysis patients, patients with acute and chronic hepatitis and patients with liver cirrhosis appeared to have increased risk of Hepatitis C virus infection. The results indicate that the frequency of HCV infection increases with the exposure to blood or blood products.
The occurrence of a case of human rabies in Peninsular Malaysia is reported. Despite the various control measures taken, sporadic cases of rabies have continued to occur in Peninsular Malaysia, especially in the northern states. Clinical awareness of the occurrence of rabies is therefore important and effective post-exposure prophylaxis should be instituted as soon as possible to prevent the possible occurrence of this dreaded disease.