Immunochromatographic Kit Research Articles

Evaluation of an immunochromatography rapid diagnosis kit for detection of chikungunya virus antigen in India, a dengue-endemic country

BackgroundChikungunya virus (CHIKV) and dengue virus (DENV) are arboviruses that share the same Aedes mosquito vector, and there is much overlap in endemic areas. In India, co-infection with both viruses is often reported. Clinical manifestations of Chikungunya fever is often confused with dengue fever because clinical symptoms of both infections are similar. It is, therefore, difficult to differentiate from those of other febrile illnesses, especially dengue fever. We previously developed a CHIKV antigen detection immunochromatography (IC) rapid diagnosis kit [1]. The current study examined the efficacy of previously mentioned IC kit in India, a dengue-endemic country.MethodsSera from 104 CHIKV-positive (by qRT-PCR) and/or IgM-positive (ELISA) subjects collected in 2016, were examined. Fifteen samples from individuals with CHIKV-negative/DENV-positive and 4 samples from healthy individuals were also examined. Of the 104 CHIKV-positive sera, 20 were co-infected with DENV.ResultsThe sensitivity, specificity and overall agreement of the IC assay were 93.7, 95.5 and 94.3%, respectively, using qRT-PCR as a gold standard. Also, there was a strong, statistically significant positive correlation between the IC kit device score and the CHIKV RNA copy number. The IC kit detected CHIKV antigen even in DENV-co-infected patient sera and did not cross-react with DENV NS1-positive/CHIKV-negative samples.ConclusionsThe results suggest that the IC kit is useful for rapid diagnosis of CHIKV in endemic areas in which both CHIKV and DENV are circulating.

Development and evaluation of a gold nanoparticle-based immunochromatographic strip test for the detection of canine parvovirus

Canine parvovirus (CPV) is the leading viral cause of enteritis in dogs and occurs mainly in 6- to 8-week-old pups. Rapid diagnosis of CPV under field conditions is now possible due to commercially available immunochromatographic (IC) assays. However, these commercial kits are somewhat expensive because they utilize a minimum of two monoclonal antibodies (mAbs) targeting different epitopes as capture and detector antibodies. Using only a singlemAb for both capture and detection purposemay reduce the sensitivity of the assay. In the present study, efforts were made to develop an economical assay that can be utilized for diagnosis of CPV under Indian conditions with a high level of confidence. Rabbit polyclonal antibodies (pAbs) generated against recombinant truncated VP2 proteins of CPV were used as capture antibodies because they can be produced economically, while a commercial anti-CPV mAb was used as the detector antibody. The detection limit of the test strip was 6.6×105 TCID50/ml, and it specifically detected CPV-2, CPV-2a and CPV-2b while displaying no cross-reactivity with other common canine enteric pathogens. The relative sensitivity/specificity of pAb based strip test was 71%/92% and 71%/100% in relation to the hemagglutination test and a commercial IC kit, respectively, with substantial agreement. In addition, two commercially available mAbs targeting different epitopes were also used for development of another IC assay, which showed sensitivity, and specificity of 82%/87% and 90%/98% in relation to the hemagglutination test and commercial kit. Hence, the present strip test based on a combination of mAb and pAb provides an acceptable alternative for onsite and cost-effective diagnosis of CPV infection.

An immunosensor for parasite lactate dehydrogenase detection as a malaria biomarker – Comparison with commercial test kit

This paper describes the development of an affinity sensor for the detection of Plasmodium falciparum parasite lactate dehydrogenase (pLDH) as one of the biomarkers used for malaria detection. The gold sensor was functionalised with anti-pLDH after cleaning the electrode surface to remove impurities (120 °C, 1 h). The sensor was then treated to block unreacted groups on the surface and minimise matrix interference, before applying it in a sandwich assay to detect pLDH in buffer samples using a dose concentration assay. The sensor was optimised to achieve the best detection sensitivity before using it for pLDH detection in serum samples. The developed sensor achieved a limit of detection (LOD) of 1.80 ng mL−1 and 0.70 ng mL−1 for the detection of pLDH in buffer and in serum samples respectively. The sensor sensitivity was enhanced further with the use of AuNP conjugated to the detection anti-pLDH-enzyme, achieving an LOD of 19 pg mL−1 in buffer and 23 pg mL−1 in serum samples. The performance of the sensor was compared to commercially available Plasmodium immunochromatographic (ICT) malaria kits. The developed sensor was able to detect pLDH in the Dd2luc culture medium supernatant at 0.002% parasitaemia without the use of AuNP signal enhancement when compared to the OptiMAL-IT ICT kit (detect pLDH) and the BinaxNOW ICT kit (detection of both pLDH and PfHRP 2) samples. Therefore, the sensor developed in this work is highly sensitive and can be used for pLDH detection for on-site diagnosis of malaria. A cheap and simple device as developed in this work is required to tackle malaria detection.

Molecular characterization of canine parvovirus variants (CPV-2a, CPV-2b, and CPV-2c) based on the VP2 gene in affected domestic dogs in Ecuador.

AimThe objective of this study was to determine the presence of the variants of canine parvovirus (CPV)-2 in the city of Quito, Ecuador, due to the high domestic and street-type canine population, and to identify possible mutations at a genetic level that could be causing structural changes in the virus with a consequent influence on the immune response of the hosts.Materials and MethodsThirty-five stool samples from different puppies with characteristic signs of the disease and positives for CPV through immunochromatography kits were collected from different veterinarian clinics of the city. Polymerase chain reaction and DNA sequencing were used to determine the mutations in residue 426 of the VP2 gene, which determines the variants of CPV-2; in addition, four samples were chosen for complete sequencing of the VP2 gene to identify all possible mutations in the circulating strains in this region of the country.ResultsThe results revealed the presence of the three variants of CPV-2 with a prevalence of 57.1% (20/35) for CPV-2a, 8.5% (3/35) for CPV-2b, and 34.3% (12/35) for CPV-2c. In addition, complete sequencing of the VP2 gene showed amino acid substitutions in residues 87, 101, 139, 219, 297, 300, 305, 322, 324, 375, 386, 426, 440, and 514 of the three Ecuadorian variants when compared with the original CPV-2 sequence.ConclusionThis study describes the detection of CPV variants in the city of Quito, Ecuador. Variants of CPV-2 (2a, 2b, and 2c) have been reported in South America, and there are cases in Ecuador where CVP-2 is affecting even vaccinated puppies.

Modification of the Alere GIARDIA Ag TEST immunochromatography KIT methodology for its use in frozen fecal sediment of dogs and cats.

Giardia duodenalis is a worldwide intestinal parasite and is one of the most frequent protozoa species infecting dogs and cats. This study aimed to modify the methodology of Alere GIARDIA Ag TEST KIT for its use in frozen fecal sediments with different storage times in a freezer (-20°C), thus expanding the range of use of this methodology. One hundred fecal sediments from dogs (n=50) and cats (n=50) previously examined by optical microscopy for Giardia cysts were selected for this study. The agreement between the modified immunochromatography and microscopy results was calculated by Kappa coefficient. To evaluate the performance of the modified immunochromatography assay on samples with different storage time, the fecal sediments were divided into three groups according to the time of storage in a freezer: (a) ≤ 1 year (n=37); (b) > 1 year and ≤ 3 years (n=39); (c) > 10 years (max. 13 years) (n=24). The results obtained by the modified immunochromatography assay demonstrates a higher sensitivity of this technique when compared with microscopy, regardless of the frozen storage time. These results allow for the use of this methodology in a greater scope of analysis, especially in frozen fecal sediment triage in sample collections, enabling epidemiological and comparative analysis along different decades.

HBsAg and Anti-HCV Prevalence among Pregnant Women Accessing Antenatal Care in a Tertiary Healthcare Facility in Central Nigeria

Background: Hepatitis B and C viral infections during pregnancy are associated with high risk of maternal complications and mortality. There is high prevalence of vertical transmission causing fetal and neonatal hepatitis which can have serious effects on the neonate, leading to impaired physical and mental health later in life. This study was aimed at evaluating HBsAg and Anti-HCV prevalence of these viruses among pregnant women accessing antenatal care in Federal Medical Centre, Keffi, Nigeria.Materials and methods: This prospective cross sectional study took place between May-July 2016. A total of 200 blood samples were collected from pregnant women after informed consent and self-administered questionnaires were completed. Blood samples were analyzed using HBsAg and anti-HCV immunochromatographic screening kits (Fastep Polymed Therapeutics Inc, USA). Chi square test (Smith’s Statistical Package Version 2.80, California, USA) was used for assessing the association of risk factors with the infections.Results: The overall level of positivity for both viruses in the study population was 14.0%. The prevalence of HBsAg was 8.0% while Anti-HCV was 6.0% and no woman was coinfected with the 2 viruses. The infection rate was highest among those aged 21-30 years old and 31-40 years old for HBV and HCV respectively (p>0.05). There was a statistically significant association between the viral infections and history of blood transfusion (p 0.05) in this study. However, educational status, stage of pregnancy, type of marriage, parity and scarification marks did not show any statistically significant association with HBV and HCV infections (p>0.05), although there were arithmetic differences among the studied risk factors (p>0.05).Conclusion: The study confirms a high prevalence of HBsAg and Anti-HCV among pregnant women in Central Nigeria which is a serious public health problem that cannot be downplayed. Therefore, there is need for establishment of public health measures in order to reduce disease burden and vertical transmission, including routine screening of all pregnant women for these viruses.

Performance of fluorescence microspheres-based immunochromatography in simultaneous monitoring of five quinoxalines

ABSTRACTQuinoxaline antibiotics are widely employed in the animal feeding and breeding industry and their metabolites transfer to the environment via the ecological cycle. In this study, fluorescence microspheres-based immunochromatography has been established for the simultaneous detection of five classical quinoxalines in environmental water and animal foodstuffs. Under the optimal conditions, it achieved qualitative and quantitative detection of five quinoxalines within 15 min. The visual limit of detection (LOD) for five quinoxalines in environmental water and animal foodstuffs was 5–15 µg/L and 100–250 µg/kg, respectively. Besides, assisted by a strip reader, the LOD for the quantitative detection of five quinoxalines was 0.09–2.04 µg/kg. The average recoveries for spiked samples ranged from 74.54% to 126.33%, with the coefficients of variation less than 28.21%. Thirty-four samples collected from different areas were detected with the developed immunochromatography and commercial enzyme-linked immunosorbent kits; the results of the two methods showed a good correlation.

Rapid and broad detection of H5 hemagglutinin by an immunochromatographic kit using novel monoclonal antibody against highly pathogenic avian influenza virus belonging to the genetic clade 2.3.4.4.

Highly pathogenic avian influenza viruses (HPAIVs) of H5 subtype have persistently caused outbreaks in domestic poultry and wild birds worldwide and sporadically infected humans. Rapid and accurate diagnosis is one of the key strategies for the control of H5 HPAIVs. However, the sensitivity of the diagnosis of H5 HPAIVs has gradually reduced due to extensive antigenic variation during their evolution. Particularly, the previously developed immunochromatographic diagnosis kit for H5 viruses, Linjudge Flu A/H5, exhibits reduced detection of H5 HPAIVs isolated in recent years. In the present study, we established a new advanced H5 rapid immunochromatographic detection kit (New Linjudge Flu A/H5) by a combination of two anti-H5 hemagglutinin monoclonal antibodies, A64/1 previously applied in the Linjudge Flu A/H5 and A32/2, a novel monoclonal antibody generated from a clade 2.3.4.4 H5 HPAIV. The new kit broadly detected all classical and recent H5 influenza viruses and showed a higher specificity and sensitivity than the original Linjudge Flu A/H5 with recently circulating H5 HPAIVs. Furthermore, the applicability of the New Linjudge Flu A/H5 was demonstrated by detecting antigens from the swabs and tissue homogenates of naturally infected birds and experimentally infected chickens with H5N6 HPAIVs belonging to the genetic clade 2.3.4.4. Our study, therefore, can provide an effective point-of-care rapid antigen detection kit for the surveillance of H5 avian influenza viruses and as a prompt countermeasure against the current widespread of the clade 2.3.4.4 H5 HPAIVs in domestic and wild birds.

Infección por Ehrlichia canis y Anaplasma sp. en caninos atendidos en clínicas veterinarias en Barranquilla, Colombia

Objetivo. Determinar la prevalencia de la infección por Ehrlichia canis y Anaplasma sp. y su correlación con aspectos epidemiológicos y de laboratorio, en caninos atendidos en clínicas veterinarias de Barranquilla, Colombia. Materiales y Métodos. Estudio de tipo descriptivo, retrospectivo de corte transversal. Los datos se obtuvieron en los meses de enero a agosto de 2015. Se analizaron 184 caninos compatibles clínicamente con infección por Ehrlichia canis y Anaplasma sp., se utilizaron los criterios de positividad de un kit comercial de inmunocromatografía y el extendido de sangre periférica, además se recolectaron datos epidemiológicos y de laboratorio. Resultados. 63 caninos (34%) fue la prevalencia global de Ehrlichia canis y Anaplasma sp., 52/184 (28%) caninos con E. canis y 11/184 (6%) con Anaplasma sp. El hemograma de los pacientes caninos positivos con E. canis y Anaplasma sp., presentaron disminución del hematocrito, leucopenia y trombocitopenia. Conclusiones. Los hallazgos encontrados a partir de este estudio muestran una alta prevalencia y endemicidad de E. canis y Anaplasma sp. en Barranquilla en contraste con otras regiones de Colombia. Los datos del hemograma demostraron ser relevantes en el diagnóstico y pronóstico de estas enfermedades.

Simultaneous development of Kawasaki disease following acute human adenovirus infection in monozygotic twins: A case report

BackgroundThe etiology of Kawasaki disease (KD) remains unknown. However, many studies have suggested that specific genetic factors and/or some infectious agents underlie the onset of KD. Previous studies have suggested that human adenovirus (HAdV) is one of the triggering pathogens of KD. Here, we report monozygotic twin boys who sequentially developed KD in conjunction with acute HAdV type 3 (HAdV-3) infection.Case presentationThe patients were four-year-old monozygotic twin boys. The elder brother developed a high fever and was diagnosed with HAdV infection with an immunochromatographic kit for HAdV (IC-kit). He was transferred to our institute after persistent fever for 7 days. On admission, he already fulfilled all the diagnostic criteria for KD. His laboratory data were as follows: WBC, 9700/μl; CRP, 2.42 mg/dl; IFN-γ, 99.8 pg/ml; and TNF-α, 10.9 pg/ml. He received intravenous immunoglobulin (IVIG) and aspirin and responded well, with no coronary artery abnormalities. The younger brother, who was also IC-kit-positive, was hospitalized on the same day as his elder brother after persistent fever for 3 days. His data on admission were as follows: WBC, 12,600/μl; CRP, 5.54 mg/dl; IFN-γ, 105.0 pg/ml; and TNF-α, 33.6 pg/ml. Although he developed all of the typical KD symptoms by day 4, his fever subsided spontaneously on day 6 without IVIG or aspirin. However, he developed a dilation of the coronary artery in the region of the left circumflex artery bifurcation on day 10. His coronary artery dilation had resolved 3 months after onset. HAdV-3 DNA was detected with PCR in stool samples from both patients, and HAdV3 was isolated from the younger brother’s stool sample. Serum neutralizing antibodies to AdV3 were also significantly elevated in both patients, suggesting seroconversion.ConclusionsThere have been few reports of the simultaneous development of KD in monozygotic twins. Notably, both twins had an acute HAdV-3 infection immediately before they developed KD. These cases strongly suggest that KD was triggered by HAdV-3 infection, and they indicate that specific immune responses to some pathogens (such as HAdV-3), arising from genetic susceptibility, play a critical role in the pathogenesis of KD.

Emergence of norovirus GII.2 and its novel recombination during the gastroenteritis outbreak in Japanese children in mid-2016

In mid-2016, norovirus GII.2 emerged as a major cause of gastroenteritis outbreak in Japan with overall detection rate of 56.3% of norovirus cases. The differences in ORF1 and ORF2 of some norovirus GII were observed. Inter-subtype recombinants GII.Pe/GII.2, GII.P16/GII.2 and GII.P17/GII.2 were detected. Three amino acid substitutions were noted at P2 antigenic site of GII.P16/GII.2 recombinants. Furthermore, this study revealed that the current immunochromatographic kit available in Japan could be used effectively for the detection of recent GII.2 genotype.

In situ self-assembly of gold nanoparticles on hydrophilic and hydrophobic substrates for influenza virus-sensing platform

Nanomaterials without chemical linkers or physical interactions that reside on a two-dimensional surface are attractive because of their electronic, optical and catalytic properties. An in situ method has been developed to fabricate gold nanoparticle (Au NP) films on different substrates, regardless of whether they are hydrophilic or hydrophobic surfaces, including glass, 96-well polystyrene plates, and polydimethylsiloxane (PDMS). A mixture of sodium formate (HCOONa) and chloroauric acid (HAuCl4) solution was used to prepare Au NP films at room temperature. An experimental study of the mechanism revealed that film formation is dependent on surface wettability and inter particle attraction. The as-fabricated Au NP films were further applied to the colorimetric detection of influenza virus. The response to the commercial target, New Caledonia/H1N1/1999 influenza virus, was linear in the range from 10 pg/ml to 10 μg/ml and limit of detection was 50.5 pg/ml. In the presence of clinically isolated influenza A virus (H3N2), the optical density of developed color was dependent on the virus concentration (10–50,000 PFU/ml). The limit of detection of this study was 24.3 PFU/ml, a limit 116 times lower than that of conventional ELISA (2824.3 PFU/ml). The sensitivity was also 500 times greater than that of commercial immunochromatography kits.

Comparative Evaluation of Norovirus Infection in Children with Acute Gastroenteritis by Rapid Immunochromatographic Test, RT-PCR and Real-time RT-PCR.

Immunochromatographic (IC) test for norovirus detection is a rapid and simple detection method. This study evaluated the sensitivity and specificity of a recent version of R-Biopharm RIDA®QUICK Norovirus IC assay for norovirus detection in fecal specimens from children hospitalized with acute gastroenteritis. Fecal specimens were tested by IC kit in comparison with gold standard reverse transcription polymerase chain reaction (RT-PCR) and real-time RT-PCR. The IC kit showed high sensitivity and specificity comparable with PCR-based methods. None of false positive and false negative was found and the assay did not cross-react with other gastroenteritis viruses. The IC assay could detect genogroup I.5 (GI.5) and a wide range of genotypes in the GII noroviruses including GII.3, GII.4, GII.6, GII.7, GII.14, GII.15, GII.21, and also newly emerging GII.17 norovirus. In conclusion, this norovirus IC kit could be an alternative choice for rapid screening or a quick diagnostic tool for norovirus detection in fecal specimens of acute gastroenteritis patients.

Diagnosis of Dengue Virus Infection in Oral Fluid using Immunochromatographic Tests.

Dengue viral infections are diagnosed by detecting dengue NS1 antigen and dengue specific IgM/IgG antibody by traditional serological tests using patient's blood. Recently saliva is being used employed for diagnosis of different infectious diseases including dengue. In the present study, dengue NS1 antigen and anti-dengue IgM/IgG antibody were detected using rapid immunochromatographic (ICT) kits for diagnosis of dengue and compared with the results of serum ICT results performed on corresponding sera collected from the same individuals. A total of 215 suspected dengue patients were tested and dengue infection was found in 176 (81.9%) sera and 161 (74.9 %) oral fluid samples. Among the 30 dengue NS1 antigen positive sera, 28 were also positive for NS1 in oral fluid indicating high sensitivity (93.3%), specificity (100%), diagnostic accuracy (99.1%), PPV (100%) and NPV (98.9 %) of testing dengue NS1 antigen in oral fluid. Similarly oral fluid assay for anti-dengue IgM showed sensitivity, specificity, diagnostic accuracy, PPV and NPV of 87.3%, 100.0%, 95.8%, 100.0% and 94.1% respectively. Test for anti-dengue IgM/IgG in oral fluid showed sensitivity, specificity, diagnostic accuracy, PPV and NPV of 89.7%, 100.0%, 98.1%, 100.0% and 97.7% respectively. All these parameters for detection of anti-dengue IgG by ICT showed 100%in oral fluid. Thus, results from this study indicates that detection of dengue NS1 antigen or anti-dengue IgM/IgG in oral fluid is an alternative tool for dengue diagnosis. It may benefits dengue diagnosis especially in infants and children since it is easy to collect and require no additional sample processing. It also has the potential to use for epidemiological survey.
 Bangladesh J Med Microbiol 2017; 11 (1): 6-9

Toxoplasmosis in cats in northeastern Brazil: Frequency, associated factors and coinfection with Neospora caninum, feline immunodeficiency virus and feline leukemia virus.

The aim of this study was to determine the frequency and the factors associated with infection by Toxoplasma gondii and demonstrate occurrences of coinfection with Neospora caninum, the feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) in cats in the state of Bahia, Brazil. A total of 231 blood samples were collected from 201 owned cats and 30 stray cats. Serological investigations on T. gondii and N. caninum were performed using the indirect fluorescent antibody test with cutoff points of 1:64 and 1:50, respectively. To diagnose FIV and FeLV, a commercial immunochromatographic kit and a nested polymerase chain reaction (PCR) was used. Unconditional logistic regression was performed to assess the factors associated with infection by T. gondii among owned cats. The seropositivity for T. gondii among the owned cats and stray cats was 44.3% (89/201) and 53.3% (16/30), respectively. For N. caninum, the seropositivity among owned cats was 21.4% (43/201) and among stray cats, 23.3% (7/30). The copositivity between the two coccidia were 23.6% (21/201) and 37.5% (6/30), among owned and stray cats respectively. The periurban environment was a risk factor for infection by T. gondii, while infection by FIV was associated with infection by T. gondii (p<0.05) among owned cats. No association was found between T. gondii and FeLV, or between N. caninum and the retroviruses. Based on these results, it can be concluded that the cats of the present study were exposed to the agents T. gondii and N. caninum, which suggests that significant infection of intermediate hosts and or environmental contamination with oocysts was present, and that the cats coinfected with T. gondii and the retroviruses did not present any serological signs of reactivation of infection.

STUDY OF NS1 ANTIGEN DETECTION AND ASSOCIATION OF PLATELET COUNT WITH VARIOUS DENGUE SEROLOGICAL MARKERS IN DENGUE INFECTION: AN INSTITUTIONAL EXPERIENCE

Introduction: Dengue is a mosquito-borne disease caused by dengue virus. Annually, it affects up millions of people worldwide. An early and accurate diagnosis of dengue in the acute phase of illness is important for identifying an epidemic and for initiation of therapy. Detection of the secreted NS1 protein is a new approach that aid in the early diagnosis. Platelet count is the only non-dengue parameter that can support the diagnosis of the dengue shock syndrome and dengue. This study was done to detect dengue parameters and correlate them with the platelet count. Material and Methods: This study was conducted from September 2016 to November 2016. Total 205 blood samples were collected from clinically suspected dengue cases. Serum was separated and tested for NS1 antigen, IgM and IgG using the immunochromatography kit. The platelet count was also recorded in all samples. Results: Out of 205 samples tested total 92(44.9%) specimens were positive for one or more dengue parameters. Among 92 specimens 45(49%) were positive for only NS1 antigen and 20 were positive for IgM only. Thrombocytopenia was recorded in 73(79%)out of 92 dengue positive cases. Conclusion: Inclusion of NS1 in the diagnosis of dengue increases the detection rate significantly in early phase of the infection.

Rapid detection of vaginitis in reproductive age group-by immunochromatography method

Vaginitis is the most frequent gynaecologic diagnosis encountered by physician providing primary care to the women. It is defined as inflammation and/or irritation of the vagina, a troublesome condition that affects millions of women in all parts of the world. A total of 50 women of reproductive age within 15-45 years, both pregnant and non-pregnant with abnormal vaginal discharge were enrolled in the study. Vaginal fluid was collected from the patients attending outpatient department of Dhaka Medical College &amp; Hospital. A rapid vaginal immunochromatography kit were used to test the samples for Chlamydia, Trichomonas, Candida and Gardnerellavaginalis along with pH, nitrites, protein and leucocytes. Bacterial vaginitis was diagnosed in 16%, 20% and 18% of the cases using microscopy, culture and rapid vaginal test kit respectively, whereas, was detected in 16%, 8%, 16% by microscopy, culture and rapid vaginal kit respectively in case of bacterial vaginosis. Chlamydia(6.66%) and Trichomonas (6.66%) was detected in the vaginal kit and Candida was detected in 3.33% cases using all three methods. Rapid vaginal kit is a simple, rapid test (result within 10 minutes) and can be used as a point of care test or for screening large number of samples.&#x0D; Bangladesh J Med Microbiol 2016; 10 (2): 18-21

Immunological detection of denatured proteins as a method for rapid identification of food residues on archaeological pottery

Our understanding of human diet in different periods of history can be enhanced by investigating direct evidence represented by accidentally preserved food remains found on pottery. So far, this task has been accomplished by the application of gas chromatography/mass spectrometry, often in combination with stable isotope analysis. These methods require specialised laboratories and their cost prevents wider penetration into the daily practice of archaeology and related disciplines. We have tested commercially available immunochromatographic kits for this task, which are designed to detect contaminants and allergens in the modern food industry. Unlike the previously published studies on archaeological material, we focus specifically on the identification of damaged and denatured proteins, which correspond better to the state of preservation of proteins in desiccated and carbonised organic residues that have survived from antiquity. We report the first successful qualitative detection of bird eggs, animal meat, milk (and species of origin), and to some extent also the presence of plant food, especially cereals and hazelnuts. The immunoassay is a methodology that is well suited for use in the field and resource-poor environments, so it is ideal for most archaeological excavations and museums. With necessary caution, the results can be used as a proxy for human diet in the past and reconstructions of anthropogenically modified environments.

Evaluation of Four Commercial Kits Based on Immunochromatography for Screening Aflatoxin M1 in Milk.

In Japan, a regulatory limit of 0.5 μg/kg was set in 2015 for aflatoxin M1 (AFM1) in milk. A method using an immunochromatographic kit has been adopted as the official screening method, and criteria for the kit have been set. In order to confirm whether commercial immunochromatographic kits for detecting AFM1 satisfy these criteria, the performance of four kits was evaluated by performing spike-and-recovery experiments using AFM1-free milk samples and milk samples spiked at seven levels (100-700 ng/kg). With the two qualitative kits, determinations of blank samples were all negative and those of the samples spiked at 500 ng/kg were all positive. With the two quantitative kits, the measured values of the blank samples were all less than 100 ng/kg and the recoveries of the samples spiked at 500 ng/kg were all more than 70%. The detection limits of the two quantitative kits were both less than 100 ng/kg. These results indicate that all four immunochromatographic kits meet the criteria and can be used to screen AFM1 in milk.

Enhanced catalytic activity of gold nanoparticle-carbon nanotube hybrids for influenza virus detection

Multifunctional nanohybrids have created new and valuable opportunities for a wide range of catalysis and biotechnology applications. Here, we present a relatively simple method for producing nanohybrids composed of gold nanoparticles (Au NPs) and carbon nanotubes (CNTs) that does not require an acidic pre-treatment of the CNTs. Transmission electron microscopy (TEM) images and ultraviolet-visible (UV–vis) spectra revealed that Au NPs bonded to the CNT surface. Surface-enhanced Raman scattering (SERS) revealed a stronger signal from Au-CNT nanohybrids than from pristine CNTs. The Au-CNT nanohybrids showed catalytic activity in the oxidation of 3, 3′, 5, 5′-tetramethyl-benzidine (TMB) by H2O2 and developed a unique blue colour in aqueous solution. Because of the enhanced peroxidase-like activity of these Au-CNT nanohybrids, they were selected for use as part of a highly sensitive colorimetric test for influenza virus A (H3N2). In the presence of influenza A virus (H3N2) in the test system (specific antibody-conjugated Au CNT nanohybrids-TMB-H2O2), a deep blue colour developed, the optical density of which was dependent on the virus concentration (10–50,000 PFU/ml). The limit of detection of this proposed method was 3.4 PFU/ml, a limit 385 times lower than that of conventional ELISA (1312 PFU/ml). The sensitivity of this test was also 500 times greater than that of commercial immunochromatography kits. The nanohybrid preparation and colorimetric detection methods reported herein may be easily adapted to other nanohybrid structures with enzyme mimetic properties for broader applications in catalysis and nanobiotechnology.