Gold Nanoparticle Paper Immunoassays for Sensing the Presence of Vibrio parahaemolyticus in Oyster Hemolymph.

Seafood contamination with Vibrio bacteria is a problem for aquaculture, especially with oysters, which are often consumed raw. Current methods for diagnosing bacterial pathogens in seafood involve lab-based assays such as polymerase chain reaction or culturing, which are time consuming and must occur in a centralized location. Detection of Vibrio in a point-of-care assay would be a significant tool for food safety control measures. We report here a paper immunoassay that can detect the presence of Vibrio parahaemolyticus (Vp) in buffer and oyster hemolymph. The test uses gold nanoparticles conjugated to polyclonal anti-Vibrio antibodies in a paper-based sandwich immunoassay. A sample is added to the strip and wicked through by capillary action. If Vp is present, it results in a visible color at the test area that can be read out by eyes or a standard mobile phone camera. The assay has a limit of detection of 6.05 × 105 cfu/mL and a cost estimate of $5 per test. Receiver operating characteristic curves with validated environmental samples showed a test sensitivity of 0.96 and a specificity of 1.00. Because the assay is inexpensive and can be used on Vp directly without the requirement for culturing, or sophisticated equipment, it has the potential to be used in fieldable settings.

Association Between Aspirin Use and Gastric Adenocarcinoma: A Prospective Cohort Study.

Prospective data examining the association of aspirin use, according to dose and duration, with long-term risk of gastric adenocarcinoma in non-Asian cohorts are lacking. We evaluated the association between aspirin use and risk of gastric adenocarcinoma in two large prospective U.S. cohort studies, the Nurses' Health Study and the Health Professionals Follow-up Study. Cox proportional hazards regression models were used to calculate multivariable adjusted HRs and 95% confidence intervals (CI). Among the 159,116 participants, we documented 316 gastric adenocarcinoma cases (176 women, 140 men) over 34 years encompassing 4.5 million person-years. Among women, regular aspirin use (at least two times or more per week) was significantly associated with lower risk of gastric adenocarcinoma (multivariable HR, 0.52; 95% CI, 0.37-0.73) compared with nonregular use. However, regular aspirin use was not associated with gastric adenocarcinoma risk among men (multivariable HR, 1.08; 95% CI, 0.77-1.52; Pheterogeneity for sex = 0.003). Among women, the lower risk of gastric adenocarcinoma was more apparent with increasing duration of aspirin use (Ptrend < 0.001) and more than five tablets per week (multivariable HR, 0.51; 95% CI, 0.31-0.84). Regular, long-term aspirin use was associated with lower risk of gastric adenocarcinoma among women, but not men. The benefit appeared after at least 10 years of use and was maximized at higher doses among women. The heterogeneity by sex in the association of aspirin use with risk of gastric adenocarcinoma requires further investigation. PREVENTION RELEVANCE: Novel prevention is urgently needed to reduce incidence and mortality of gastric cancer. We found that regular aspirin use was associated with lower risk of gastric adenocarcinoma among women, but not men. The benefit appeared after at least 10 years of use and was maximized at higher doses among women. See related Spotlight, p. 213.

The COronavirus Pandemic Epidemiology (COPE) Consortium: A Call to Action.

The rapid pace of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; COVID-19) pandemic presents challenges to the real-time collection of population-scale data to inform near-term public health needs as well as future investigations. We established the COronavirus Pandemic Epidemiology (COPE) consortium to address this unprecedented crisis on behalf of the epidemiology research community. As a central component of this initiative, we have developed a COVID Symptom Study (previously known as the COVID Symptom Tracker) mobile application as a common data collection tool for epidemiologic cohort studies with active study participants. This mobile application collects information on risk factors, daily symptoms, and outcomes through a user-friendly interface that minimizes participant burden. Combined with our efforts within the general population, data collected from nearly 3 million participants in the United States and United Kingdom are being used to address critical needs in the emergency response, including identifying potential hot spots of disease and clinically actionable risk factors. The linkage of symptom data collected in the app with information and biospecimens already collected in epidemiology cohorts will position us to address key questions related to diet, lifestyle, environmental, and socioeconomic factors on susceptibility to COVID-19, clinical outcomes related to infection, and long-term physical, mental health, and financial sequalae. We call upon additional epidemiology cohorts to join this collective effort to strengthen our impact on the current health crisis and generate a new model for a collaborative and nimble research infrastructure that will lead to more rapid translation of our work for the betterment of public health.

Detection of resistance protein A (MxA) in paper-based immunoassays with surface enhanced Raman spectroscopy with AuAg nanoshells.

Myxovirus protein A (MxA) is a biomarker that can be used to distinguish between viral and bacterial infections. While MxA lateral flow assays (LFAs) have been successfully used for viral vs. bacterial differential diagnosis for children, the clinically relevant level of MxA for adults has been reported to be 100 times lower, which is too low for traditional LFAs. We present results applying the use of surface enhanced Raman spectroscopy (SERS) to detect MxA. AuAg nanoshells (AuAg NSs) were used to enhance the Raman signal of mercaptobenzoic acid (4-MBA), enabling readout by SERS. The AuAg NSs were conjugated to antibodies for the biomarker of interest, resulting in a "nanotag", that could be used in a dipstick immunoassay for detection. We first optimized the nanotag parameters using anti-human IgG/human IgG as a model antibody/antigen system, and then demonstrated detection of MxA using anti-MxA antibodies. We show that SERS readout of immunoassays for MxA can quantify MxA levels at clinically relevant levels for adult viral infection.

Reporter Selection for Nanotags in Multiplexed Surface Enhanced Raman Spectroscopy Assays.

We report a quantitative evaluation of the choice of reporters for multiplexed surface-enhanced Raman spectroscopy (SERS). An initial library consisted of 15 reporter molecules that included commonly used Raman dyes, thiolated reporters, and other small molecules. We used a correlation matrix to downselect Raman reporters from the library to choose five candidates: 1,2-bis(4-pyridyl)ethylene, 4-mercaptobenzoic acid, 3,5-dichlorobenzenthiol, pentachlorothiophenol, and 5,5'-dithiobis(2-nitrobenzoic acid). We evaluated the ability to distinguish the five SERS reporters in a dipstick immunoassay for the biomarker human IgG. Raman nanotags, or gold nanostars conjugated to the five reporters and anti-human IgG polyclonal antibodies were constructed. A linear discriminant analysis approach was used to evaluate the separation of the nanotag spectra in mixtures of fixed ratios.