Trajectory of Viral RNA Load Among Persons With Incident SARS-CoV-2 G614 Infection (Wuhan Strain) in Association With COVID-19 Symptom Onset and Severity

IMPORTANCE

The SARS-CoV-2 viral trajectory has not been well characterized in incident infections. These data are needed to inform natural history, prevention practices, and therapeutic development.

OBJECTIVE

To characterize early SARS-CoV-2 viral RNA load (hereafter referred to as viral load) in individuals with incident infections in association with COVID-19 symptom onset and severity.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study was a secondary data analysis of a remotely conducted study that enrolled 829 asymptomatic community-based participants recently exposed (<96 hours) to persons with SARS-CoV-2 from 41 US states from March 31 to August 21, 2020. Two cohorts were studied: (1) participants who were SARS-CoV-2 negative at baseline and tested positive during study follow-up, and (2) participants who had 2 or more positive swabs during follow-up, regardless of the initial (baseline) swab result. Participants collected daily midturbinate swab samples for SARS-CoV-2 RNA detection and maintained symptom diaries for 14 days.

EXPOSURE

Laboratory-confirmed SARS-CoV-2 infection.

MAIN OUTCOMES AND MEASURES

The observed SARS-CoV-2 viral load among incident infections was summarized, and piecewise linear mixed-effects models were used to estimate the characteristics of viral trajectories in association with COVID-19 symptom onset and severity.

RESULTS

A total of 97 participants (55 women [57%]; median age, 37 years [IQR, 27-52 years]) developed incident infections during follow-up. Forty-two participants (43%) had viral shedding for 1 day (median peak viral load cycle threshold [Ct] value, 38.5 [95% CI, 38.3-39.0]), 18 (19%) for 2 to 6 days (median Ct value, 36.7 [95% CI, 30.2-38.1]), and 31 (32%) for 7 days or more (median Ct value, 18.3 [95% CI, 17.4-22.0]). The cycle threshold value has an inverse association with viral load. Six participants (6%) had 1 to 6 days of viral shedding with censored duration. The peak mean (SD) viral load was observed on day 3 of shedding (Ct value, 33.8 [95% CI, 31.9-35.6]). Based on the statistical models fitted to 129 participants (60 men [47%]; median age, 38 years [IQR, 25-54 years]) with 2 or more SARS-CoV-2-positive swab samples, persons reporting moderate or severe symptoms tended to have a higher peak mean viral load than those who were asymptomatic (Ct value, 23.3 [95% CI, 22.6-24.0] vs 30.7 [95% CI, 29.8-31.4]). Mild symptoms generally started within 1 day of peak viral load, and moderate or severe symptoms 2 days after peak viral load. All 535 sequenced samples detected the G614 variant (Wuhan strain).

CONCLUSIONS AND RELEVANCE

This cohort study suggests that having incident SARS-CoV-2 G614 infection was associated with a rapid viral load peak followed by slower decay. COVID-19 symptom onset generally coincided with peak viral load, which correlated positively with symptom severity. This longitudinal evaluation of the SARS-CoV-2 G614 with frequent molecular testing serves as a reference for comparing emergent viral lineages to inform clinical trial designs and public health strategies to contain the spread of the virus.

COVID-19 Prevalence in UNIVI Group Nursing Homes and Multilevel Geriatric Hospitals: Epidemiological Study of Immunological Status with Rapid Serological Tests for Diagnostic Guidance and Follow Up

BACKGROUND/OBJECTIVES

To date, data are lacking on the proportion of residents, and employees who have actually been exposed to SARS-Cov-2 in nursing homes and geriatric healthcare institutions, as well as the evolution of their serological status and the recurrence of Covid-19. The primary objective was to determine the prevalence of COVID-19 using NG Biotech rapid serological tests among caregivers and residents. The secondary objectives were to determine: prevalence according to RT PCR tests or clinical diagnosis; the risk factors (autonomy, arterial hypertension, diabetes mellitus) and clinical presentation (e.g. respiratory, abdominal or cutaneous symptoms, asthenia, fever) among residents; the risk factors (age, sex, profession, family situation) among caregivers; the evolution of the serological status at 1, 3 and 6 months using NG Biotech rapid serological tests; the symptomatic recurrence of Covid 19 at 1, 3 and 6 months.

DESIGN

Multicentric prospective observational.

SETTING

Study location: 27 nursing homes and 3 multilevel geriatric hospitals belonging to the UNIVI Group in France.

PARTICIPANTS

1334 professionals: 692 among multilevel geriatric hospitals (mean age: 43.6+/-11.8; 441 (82.4%) female) and 642 among nursing homes (mean age: 43.5+/-12.4; 685 (85.9%) female), and 1145 residents (mean age: 89+/-7.5; 898 (78.7%) female).

MEASUREMENTS

Prevalence using NG Biotech rapid serological tests, medical diagnosis, RT-PCR tests.Risk factors among residents using the medical file and among caregivers using questionnaires.Clinical presentation in residents using the medical file.

RESULTS

The prevalence using NG Biotech rapid serological test in residents was 14.4 % (168 of 1142 available diagnostics), the global prevalence (positive RT-PCR or positive serological test) was 22.7% (203 of 895 available diagnostics). The prevalence using NG Biotech rapid serological test in professionals was 12.8% (164 of 1315 available diagnostics), the global prevalence (positive RT-PCR test or positive serological test) was 23.8% (222 of 933 available diagnostics). The risk factors among residents were: living in an Alzheimer unit, and being a contact case. Being independent for activities of daily living was protective. The risk factor among caregivers was being a contact case. Another risk factor was the job; nurse assistants, nurses, and physicians were the most exposed. Residents had atypical clinical presentations including frequent geriatric syndromes (falls, delirium). 68.3% (71 of 104) of the initially positive residents still had a positive rapid serological test at 1 month follow up and 74 % (54 of 73) at 3 months follow up. 77.9% (88 of 113) of the initially positive employees still had a positive rapid serological test at 1 month follow up. Symptomatic reinfection was exceptional in caregivers or in residents during follow up.

CONCLUSION

COVID 19 prevalence among caregivers and residents in nursing homes and geriatric health Institutions is underestimated when using only one method for diagnosis. Geriatric syndromes such as falls and delirium in residents should trigger further investigations on a COVID-19 cause. Immunity was persistent in ¾ of caregivers and residents during the 3 months follow up. The high prevalence of COVID 19 in geriatric institutions pleads in favor of the French vaccination policy, initially targeting as a priority the most vulnerable and dependent people, followed by staff members in healthcare institutions and nursing homes. More studies on the persistence of immunity and the perspective of Covid 19 mutations will help determine the long-term vaccine booster policy.

Multiple-bead assay for the differential serodiagnosis of neglected human cestodiases: Neurocysticercosis and cystic echinococcosis

BACKGROUND

Neurocysticercosis (NCC), and cystic echinococcosis (CE) are two neglected diseases caused by cestodes, co-endemic in many areas of the world. Imaging studies and serological tests are used in the diagnosis of both parasitic diseases, but cross-reactions may confound the results of the latter. The novel multiplex bead-based assay with recombinant antigens has been reported to increases the diagnostic accuracy of serological techniques.

METHODOLOGY

We set-up an immunoassay based on the multiplex bead-based platform (MBA), using the rT24H (against Cysticercus cellulosae, causing cysticercosis) and r2B2t (against Echinococcus granulosus sensu lato, causing CE) recombinant antigens, for simultaneous and differential diagnosis of these infections. The antigens were tested on 356 sera from 151 patients with CE, 126 patients with NCC, and 79 individuals negative for both diseases. Specificity was calculated including sera from healthy donors, other neurological diseases and the respective NCC or CE sera counterpart. The diagnostic accuracy of this assay was compared with two commercial ELISA tests, Novalisa and Ridascreen, widely used in the routine diagnosis of cysticercosis and CE, respectively.

MAIN FINDINGS

For the diagnosis of NCC, sensitivity ranged from 57.94-63.49% for the rT24H-MBA, and 40.48-46.03% for Novalisa ELISA depending on exclusion or inclusion of sera having equivocal results on ELISA from the analysis; specificities ranged from 90.87-91.30% and 70.43-76.96%, respectively. AUC values of the ROC curve were 0.783 (rT24H) and 0.619 (Novalisa) (p-value < 0.001). For the diagnosis of CE, the sensitivity of the r2B2t-MBA ranged from 68.87-69.77% and of Ridascreen ELISA from 50.00-57.62%; specificities from 92.47-92.68% and from 74.15-80.98%, respectively. AUC values were 0.717 and 0.760, respectively.

CONCLUSIONS/SIGNIFICANCE

Overall, the recombinant antigens tested with the bead-based technology showed better diagnostic accuracy than the commercial assays, particularly for the diagnosis of NCC. The possibility of testing the same serum sample simultaneously for the presence of antibodies against both antigens is an added value particularly in seroprevalence studies for cysticercosis linked to control programs in endemic areas where these two parasites coexist.

Detection of SARS-CoV-2 variants by Abbott molecular, antigen, and serological tests

Background

: Viral diversity presents an ongoing challenge for diagnostic tests, which need to accurately detect all circulating variants. The Abbott Global Surveillance program monitors severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants and their impact on diagnostic test performance.

Objectives

: To evaluate the capacity of Abbott molecular, antigen, and serologic assays to detect circulating SARS-CoV-2 variants, including all current variants of concern (VOC): B.1.1.7 (alpha), B.1.351 (beta), P.1 (gamma) and B.1.617.2 (delta).

Study design

: Dilutions of variant virus cultures (B.1.1.7, B.1.351, B.1.429, B.1.526.1, B.1.526.2, B.1.617.1, B.1.617.2, P.1, R.1 and control isolate WA1) and a panel of N = 248 clinical samples from patients with sequence confirmed variant infections (B.1.1.7, B.1.351, B.1.427, B.1.429, B.1.526, B.1.526.1, B.1.526.2, P.1, P.2, R.1) were evaluated on at least one assay: Abbott ID NOW COVID-19, m2000 RealTime SARS-CoV-2, Alinity m SARS-CoV-2, and Alinity m Resp-4-Plex molecular assays; the BinaxNOW COVID-19 Ag Card and Panbio COVID-19 Ag Rapid Test Device; and the ARCHITECT/Alinity i SARS-CoV-2 IgG and AdviseDx IgM assays, Panbio COVID-19 IgG assay, and ARCHITECT/Alinity i AdviseDx SARS-CoV-2 IgG II assay.

Results

: Consistent with in silico predictions, each molecular and antigen assay detected VOC virus cultures with equivalent sensitivity to the WA1 control strain. Notably, 100% of all tested variant patient specimens were detected by molecular assays (N = 197 m2000, N = 88 Alinity m, N = 99 ID NOW), and lateral flow assays had a sensitivity of >94% for specimens with genome equivalents (GE) per device above 4 log (85/88, Panbio; 54/57 Binax). Furthermore, Abbott antibody assays detected IgG and IgM in 94–100% of sera from immune competent B.1.1.7 patients 15–26 days after symptom onset.

Conclusions

: These data confirm variant detection for 11 SARS-CoV-2 assays, which is consistent with each assay target region being highly conserved. Importantly, alpha, beta, gamma, and delta VOCs were detected by molecular and antigen assays, indicating that these tests may be suitable for widescale use where VOCs predominate.

Highly Sensitive and Specific SARS-CoV-2 Serological Assay Using a Magnetic Modulation Biosensing System

Sensitive serological assays are needed to provide valuable information about acute and past viral infections. For example, detection of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG antibodies could serve as the basis for an "immunity passport" that would enable individuals to travel internationally. Here, utilizing a novel Magnetic Modulation Biosensing (MMB) system and the receptor-binding domain of the SARS-CoV-2 spike protein, we demonstrate a highly sensitive and specific anti-SARS-CoV-2 IgG serological assay. Using anti-SARS-CoV-2 IgG antibodies, RT-qPCR SARS-CoV-2-positive and healthy patients' samples, and vaccinees' samples, we compare the MMB-based SARS-CoV-2 IgG assay's analytical and clinical sensitivities to those of the enzyme-linked immunosorbent assay (ELISA). Compared with ELISA, the MMB-based assay has an ~6-fold lower limit of detection (129 ng/L vs. 817 ng/L), and it detects an increase in the IgG concentration much earlier after vaccination. Using 85 RT-qPCR SARS-CoV-2-positive samples and 79 -negative samples, the MMB-based assay demonstrated similar clinical specificity (98% vs. 99%) and sensitivity (93% vs. 92%) to the ELISA test, but with a much faster turnaround time (45 min vs. 245 min). The high analytical and clinical sensitivity, short turnaround time, and simplicity of the MMB-based assay makes it a preferred method for antibody detection.

The Standardization and Control of Serology and Nucleic Acid Testing for Infectious Diseases

Historically, the detection of antibodies against infectious disease agents was achieved using test systems that utilized biological functions such as neutralization, complement fixation, hemagglutination, or visualization of binding of antibodies to specific antigens, by testing doubling dilutions of the patient sample to determine an endpoint. These test systems have since been replaced by automated platforms, many of which have been integrated into general medical pathology. Methods employed to standardize and control clinical chemistry testing have been applied to these serology tests. However, there is evidence that these methods are not suitable for infectious disease serology. An overriding reason is that, unlike testing for an inert chemical, testing for specific antibodies to infectious disease agents is highly variable; the measurand for each test system varies in choice of antigen, antibody classes/subclasses, modes of detection, and assay kinetics, and individuals' immune responses vary with time after exposure, individual immune-competency, nutrition, treatment, and exposure to variable circulating sero- or genotypes or organism mutations. Therefore, unlike that of inert chemicals, the quantification of antibodies cannot be standardized using traditional methods. However, there is evidence that the quantification of nucleic acid testing, reporting results in international units, has been successful across many viral load tests. Similarly, traditional methods used to control clinical chemistry testing, such as Westgard rules, are not appropriate for serology testing for infectious diseases, mainly due to variability due to frequent reagent lot changes. This review investigates the reasons why standardization and control of infectious diseases should be further investigated and more appropriate guidelines should be implemented.

Development of an Indirect ELISA Based on Spike Protein to Detect Antibodies against Feline Coronavirus

Feline coronavirus (FCoV) is a pathogenic virus commonly found in cats that causes a benign enteric illness and fatal systemic disease, feline infectious peritonitis. The development of serological diagnostic tools for FCoV is helpful for clinical diagnosis and epidemiological investigation. Therefore, this study aimed to develop an indirect enzyme-linked immunosorbent assay (iELISA) to detect antibodies against FCoV using histidine-tagged recombinant spike protein. FCoV S protein (1127–1400 aa) was expressed and used as an antigen to establish an ELISA. Mice and rabbits immunized with the protein produced antibodies that were recognized and bound to the protein. The intra-assay coefficient of variation (CV) was 1.15–5.04% and the inter-assay CV was 4.28–15.13%, suggesting an acceptable repeatability. iELISA did not cross-react with antisera against other feline viruses. The receiver operating characteristic curve analysis revealed an 86.7% sensitivity and 93.3% specificity for iELISA. Serum samples (n = 107) were tested for anti-FCoV antibodies, and 70.09% of samples were positive for antibodies against FCoV. The iELISA developed in our study can be used to measure serum FCoV antibodies due to its acceptable repeatability, sensitivity, and specificity. Additionally, field sample analysis data demonstrated that FCoV is highly prevalent in cat populations in Fujian province, China.

Detection of Treponema pallidum DNA in Oropharyngeal Swabs and Whole Blood for Syphilis Diagnosis

BACKGROUND

Syphilis diagnosis relies on serological tests, which may be falsely nonreactive or may be reactive but not reflect current syphilis.

METHODS

Polymerase chain reaction for detection of T. pallidum DNA was performed on 123 oropharyngeal swabs, 120 whole bloods, and 46 lesion exudate swabs from 123 untreated individuals with syphilis (cases); oropharyngeal swabs from 148 at-risk controls without syphilis; and 73 oropharyngeal swabs and 36 whole bloods from 73 individuals recently treated for syphilis.

RESULTS

Most (90.2%) cases had early syphilis. T. pallidum DNA was detected in 33 (26.8%) of 123 oropharyngeal swabs, 32 (26.7%) of 120 bloods, and 30 (65.2%) of 46 lesion exudate swabs. T. pallidum DNA was detected in 49 (40.8%) of 120 individuals in whom both oropharyngeal swabs and blood were tested. T. pallidum was more likely to be amplified from oropharyngeal swabs when it was amplified from blood than when it was not (15 of 32 [46.9%] vs. 17 of 88 [19.3%], P = 0.003). For each 2-fold increase in serum rapid plasma reagin titer, the odds of detection of T. pallidum DNA in oropharyngeal swabs increased by 1.44 (95% confidence interval, 1.14-1.82, P = 0.003). T. pallidum DNA was not detected in oropharyngeal samples from controls, but it was detected in 3 (8.3%) of 36 bloods from individuals recently treated for syphilis: 2 at 1 day and 1 at 5 days after initiation of syphilis treatment.

CONCLUSIONS

Nucleic amplification tests can identify recent T. pallidum infection and may be particularly useful for diagnosis of very early or asymptomatic syphilis.

Global estimates of viral suppression in children and adolescents and adults on antiretroviral therapy adjusted for missing viral load measurements: a multiregional, retrospective cohort study in 31 countries

BACKGROUND

As countries move towards the UNAIDS's 95-95-95 targets and with strong evidence that undetectable equals untransmittable, it is increasingly important to assess whether those with HIV who are receiving antiretroviral therapy (ART) achieve viral suppression. We estimated the proportions of children and adolescents and adults with viral suppression at 1, 2, and 3 years after initiating ART.

METHODS

In this retrospective cohort study, seven regional cohorts from the International epidemiology Databases to Evaluate AIDS (IeDEA) consortium contributed data from individuals initiating ART between Jan 1, 2010, and Dec 31, 2019, at 148 sites in 31 countries with annual viral load monitoring. Only people with HIV who started ART after the time a site started routine viral load monitoring were included. Data up to March 31, 2020, were analysed. We estimated the proportions of children and adolescents (aged <18 years at ART initiation) and adults (aged ≥18 years at ART initiation) with viral suppression (viral load <1000 copies per mL) at 1, 2, and 3 years after ART initiation using an intention-to-treat approach and an adjusted approach that accounted for missing viral load measurements.

FINDINGS

21 594 children and adolescents (11 812 [55%] female, 9782 [45%] male) from 106 sites in 22 countries and 255 662 adults (163 831 [64%] female, 91 831 [36%] male) from 143 sites in 30 countries were included. Using the intention-to-treat approach, the proportion of children and adolescents with viral suppression was 7303 (36%) of 20 478 at 1 year, 5709 (30%) of 19 135 at 2 years, and 4287 (24%) of 17 589 at 3 years after ART initiation; the proportion of adults with viral suppression was 106 541 (44%) of 240 600 at 1 year, 79 141 (36%) of 220 925 at 2 years, and 57 970 (29%) of 201 124 at 3 years after ART initiation. After adjusting for missing viral load measurements among those who transferred, were lost to follow-up, or who were in follow-up without viral load testing, the proportion of children and adolescents with viral suppression was 12 048 (64% [plausible range 43-81]) of 18 835 at 1 year, 10 796 (62% [41-77]) of 17 553 at 2 years, and 9177 (59% [38-91]) of 15 667 at 3 years after ART initiation; the proportion of adults with viral suppression was 176 964 (79% [53-80]) of 225 418 at 1 year, 145 552 (72% [48-79]) of 201 238 at 2 years, and 115 260 (65% [43-69]) of 178 458 at 3 years after ART initiation.

INTERPRETATION

Although adults with HIV are approaching the global target of 95% viral suppression, progress among children and adolescents is much slower. Substantial efforts are still needed to reach the viral suppression target for children and adolescents.

FUNDING

US National Institutes of Health.

Potential of recombinant LiHyQ, a novel Leishmania infantum protein, for the diagnosis of canine visceral leishmaniasis and as a diagnostic and prognostic marker for human leishmaniasis and human immunodeficiency virus co-infection: A preliminary study

Laboratory diagnosis of leishmaniasis shows variable efficacy in detecting infected mammalian hosts and there is a need to identify suitable antigens to improve the accuracy of diagnostic tests. In the present study, a L. infantum hypothetical protein called LiHyQ was evaluated for the diagnosis of tegumentary (TL) and visceral (VL) leishmaniasis using canine and human samples. A collection of dog sera (n=155) were tested and contained samples from asymptomatic (n=20) and symptomatic (n=25) VL animals, from healthy dogs living in endemic (n=25) or non-endemic (n=25) areas of disease, from Leish-Tec® vaccinated dogs (n=20) or from dogs infected with Ehrlichia canis (n=15), Babesia canis (n=10) and Trypanosoma cruzi (n=15). Sensitivity (Se), Specificity (Sp), Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of 100% were observed for rLiHyQ with these samples, whereas the Se, Sp, PPV and NPV values with L. infantum Soluble Leishmania Antigen (SLA) preparation were 60.0%, 99.0%, 96.0% and 86.0%, respectively. A collection of human sera (n=305) were tested and contained samples from TL (n=50) and VL (n=40) patients, from VL/HIV co-infected patients (n=35), from patients infected with HIV alone (n=30), Chagas Disease (n=30), malaria (n=10), tuberculosis (n=10), paracoccidioidomycosis (n=15), leprosy (n=30) or aspergillosis (n=15); and from healthy subjects (n=40). Se, Sp, PPV and NPV values of 100% were observed for rLiHyQ with these samples, whereas the Se, Sp, PPV and NPV values with SLA were 58.0%, 76.0%, 50.0% and 82.0%, respectively. The antibody reactivity against the protein was compared with commercial kits, and the kappa index varied from 0.95 to 1.00 for rLiHyQ, and of 0.55 to 0.82 for the kits. In addition, the serological follow-up of treated patients showed a significant reduction in rLiHyQ-specific IgG antibody levels. All canine and human samples were tested at the same time using the same reagents, in order to reduce experimental variation and interference in data interpretation. In conclusion, our preliminary data suggest a diagnostic and prognostic role for rLiHyQ against leishmaniasis.

A Rapid Point-of-Care Test for the Serodiagnosis of Hepatitis Delta Virus Infection

Hepatitis Delta virus (HDV) is a satellite of the Hepatitis B virus (HBV) and causes severe liver disease. The estimated prevalence of 15-20 million infected people worldwide may be underestimated as international diagnostic guidelines are not routinely followed. Possible reasons for this include the limited awareness among healthcare providers, the requirement for costly equipment and specialized training, and a lack of access to reliable tests in regions with poor medical infrastructure. In this study, we developed an HDV rapid test for the detection of antibodies against the hepatitis delta antigen (anti-HDV) in serum and plasma. The test is based on a novel recombinant large hepatitis delta antigen that can detect anti-HDV in a concentration-dependent manner with pan-genotypic activity across all known HDV genotypes. We evaluated the performance of this test on a cohort of 474 patient samples and found that it has a sensitivity of 94.6% (314/332) and a specificity of 100% (142/142) when compared to a diagnostic gold-standard ELISA. It also works robustly for a broad range of anti-HDV titers. We anticipate this novel HDV rapid test to be an important tool for epidemiological studies and clinical diagnostics, especially in regions that currently lack access to reliable HDV testing.

Occurrence of SARS-CoV-2 infection among healthcare personnel: results from an early systematic review and meta-analysis

BACKGROUND

SARS-CoV-2 infection has become a global public health concern globally. Even though Healthcare Workers (HCWs) are supposedly at increased risk for SARS-CoV-2 infection, to date no pooled evidence has been collected.

MATERIALS AND METHODS

We searched online electronic databases (PubMed, Embase, medRxiv.org for pre-prints) for all available contribution (up to May 20, 2019). Two Authors independently screened articles and extracted the data. The pooled prevalence of SARS-CoV-2 was analyzed using the random-effects model. The possible sources of heterogeneity were analyzed through subgroup analysis, and meta-regression.

RESULTS

The overall pooled prevalence of SARS-CoV-2 was 3.5% (95%CI 1.8-6.6) for studies based on molecular assays, 5.5% (95%CI 2.1-14.1) for studies based on serological assays, and 6.5% (95%CI 2.5-15.6) for point-of-care capillary blood tests. Among subgroups, serological tests identified higher risk for SARS-CoV-2 seropositivity in physicians than in nurses (OR 1.436, 95%CI 1.026 to 2.008). Regression analysis indicated the possible presence of publication bias only for molecular tests (t -3.3526, p-value 0.002648).

CONCLUSIONS

The overall pooled prevalence of SARS-CoV-2 was lower than previously expected, but available studies were affected by significant heterogeneity, and the molecular studies by significant publication bias. Therefore, further high-quality research in the field is warranted.

Detection of Brucella Abortus Using Nested-PCR Molecular Method

BACKGROUND

Common detection methods of brucellosis are always accompanied by technical problems in infection diagnosis. In this study, the nested PCR technique was used for the detection of Brucella abortus, and it was compared with other methods.

METHODS

This case-control study was done in Kurdistan. Blood samples were collected from 50 patients with clinical symptoms and 50 healthy people with no clinical symptoms. Serologic and culture tests were done for all the samples. DNA was extracted using a Promega kit. Molecular detection was done by nested PCR. In the end, the results of phenotypical method and nested PCR were compared.

RESULTS

The results of culture and serology tests indicate the limited capabilities of these methods to detect Brucella species. According to the results among all samples, only 14 (28%) were cultured. Rose Bengal test sensitivity was 100% but its specificity 26.09%. Also, Wright's test (tube agglutination) sensitivity was also 85% and nested PCR sensitivity was 46.15%.

CONCLUSIONS

The sensitivity of Rose Bengal, Wright's and nested PCR tests were 100%, 85%, and 46.15%, respectively, for this sampling.

Establishment of a specimen panel for the decentralised technical evaluation of the sensitivity of 31 rapid diagnostic tests for SARS-CoV-2 antigen, Germany, September 2020 to April 2021

IntroductionThe detection of SARS-CoV-2 with rapid diagnostic tests (RDT) has become an important tool to identify infected people and break infection chains. These RDT are usually based on antigen detection in a lateral flow approach.AimWe aimed to establish a comprehensive specimen panel for the decentralised technical evaluation of SARS-CoV-2 antigen rapid diagnostic tests.MethodsWhile for PCR diagnostics the validation of a PCR assay is well established, there is no common validation strategy for antigen tests, including RDT. In this proof-of-principle study we present the establishment of a panel of 50 pooled clinical specimens that cover a SARS-CoV-2 concentration range from 1.1 × 109 to 420 genome copies per mL of specimen. The panel was used to evaluate 31 RDT in up to six laboratories.ResultsOur results show that there is considerable variation in the detection limits and the clinical sensitivity of different RDT. We show that the best RDT can be applied to reliably identify infectious individuals who present with SARS-CoV-2 loads down to 106 genome copies per mL of specimen. For the identification of infected individuals with SARS-CoV-2 loads corresponding to less than 106 genome copies per mL, only three RDT showed a clinical sensitivity of more than 60%.ConclusionsSensitive RDT can be applied to identify infectious individuals with high viral loads but not to identify all infected individuals.

Multiplex immunoassay to measure antibody response to nine HPV vaccine types

Well-characterized HPV serology assays are required to evaluate performance of biosimilar candidate vaccines, reduced dosing schedules and novel administration methods. We report characterization of an expanded assay, M9ELISA, that detects antibodies to HPV virus-like particles (VLP) of nine types using direct IgG ELISA on the Meso Scale Discovery (MSD) electrochemiluminescence platform. The method is based on the previously published M4ELISA which detects antibodies to HPV6,11,16, and 18. It has been modified to add detection of antibodies to HPV31,33,45,52 and 58, and to streamline assay and reduce background. The M9ELISA plates were prepared with purified type specific L1 + L2 VLPs coated on 10-spot/well standard MSD microplates. Results of ELISA on three serial dilutions of serum were read on MSD imager, and titers calculated using the parallel line method. Evaluations included dynamic range, assay reproducibility, and stability over time. We compared M9ELISA results to those from a pseudovirion-based neutralization assay in sera from a mixed cohort of unvaccinated and vaccinated individuals (n = ~116) and to competitive Luminex immunoassay (cLIA) results in sera from a predominantly unvaccinated cohort (n = 4426). The linear range of the assay extended over 5 logs, with inter-assay reproducibility coefficient of variation ≤25% for all types. The pre-coated plates were stable for at least 2 years. Spearman correlation of antibody titers showed excellent correlation with PBNA (r = 0.86-0.97) and moderate correlation (r = 0.52-0.68) with cLIA. Thus, the M9ELISA can serve as a useful platform for high-throughput, sensitive and simultaneous quantitation of the antibody responses to nine HPV vaccine types.

Frequency of post treatment control varies by antiretroviral therapy restart and viral load criteria

Clinical trials including an analytical treatment interruption (ATI) are vital for evaluating the efficacy of novel strategies for HIV remissions. We briefly describe an interactive tool for predicting viral rebound timing in ATI trials and the impact of posttreatment controller (PTC) definitions on PTC frequency estimates. A 4-week viral load threshold of 1000 cps/ml provides both high specificity and sensitivity for PTC detection. PTC frequency varies greatly based on the definition of a PTC.

Combined use of two rapid tests for the conclusive diagnosis of Chagas disease: a systematic scoping review

OBJECTIVE

The goal of this systematic scoping review is to collect and summarise scientific evidence regarding the validity of two simultaneous immunochromatographic tests for the conclusive diagnosis of Chagas disease. The research was informed by the following review questions: Will the use of two rapid tests be a valid method for the definitive diagnosis of Chagas disease when compared with conventional serological tests? In what type of population has the operation of two rapid tests been tried for the diagnosis of Chagas disease? What are the biomedical and public health advantages of the diagnostic method resulting from the combination of two rapid tests over the conventional serological method? Will it be a cost-benefit strategy for the diagnosis of Chagas with respect to conventional serological tests?

DESIGN

Systematic scoping review.

SETTING

A search of the published and unpublished literature in five databases was carried out, in order to identify, screen and select the studies included in this review.

RESULTS

468 studies were identified, of which 46 were screened with a full-text reading, and finally, three articles were included in the review. All studies were in endemic countries with adult and paediatric populations (n=1133) and, together, they evaluated four different rapid tests. The rapid tests showed good sensitivity (97.4%-100%) and specificity (96.1%-100%) for the diagnosis of Chagas when used in combination and compared with the reference tests.

CONCLUSIONS

The simultaneous use of at least two immunochromatographic rapid tests is a valid option for the definitive diagnosis of chronic Chagas in endemic rural areas, as long as there are studies that previously evaluate their performance on the areas of implementation. Therefore, this could be an alternative to the current diagnostic standard. However, additional studies are still needed in more countries in order to provide further evidence and to investigate the cost-benefit.

Lyme arthritis is rare in Eastern Denmark

INTRODUCTION The multi-organ disease Lyme borreliosis can cause mainly large joint arthritis. No guideline exists describing how to diagnose Lyme arthritis (LA). The incidence of LA in Denmark remains unknown, but it is considered to be low. The primary aim of this study was to quantify the number of Borrelia burgdorferi serological tests requested from primary and secondary care; secondly, to examine how often LA is diagnosed. METHODS this was a register-based study including B. burgdorferi serological tests analysed at the department of clinical microbiology at Hvidovre and Herlev Hospitals during a two-year period. The results of the tests were categorised into primary and secondary care. A medical record review was made covering all newly referred rheumatological patients with B. burgdorferi serological tests analysed the Department of Clinical Microbiology, Hvidovre Hospital. A model was set up to diagnose LA. RESULTS Most tests were requested by primary care. A total of 146 rheumatology patients were tested for B. burgdorferi of whom 118 were newly referred. Using our model to diagnose LA, we found that three patients had possible LA, whereas one had likely LA, but none were given a final LA diagnosis. Overdiagnosis was not common among rheumatologists. CONCLUSION. The number of requested B. burgdorferi serological tests was highest in primary care. A clear guideline describing how to diagnose LA is needed in primary and secondary care alike. FUNDING none. TRIAL REGISTRATION Under current Danish law, no formal ethical approval was required for this study. Approval for this study was obtained from the Danish Data Protection Agency (no. 2012-58-0004).

Implementing Serosurveys in India: Experiences, Lessons Learned, and Recommendations

Serological surveillance for vaccine-preventable diseases, such as measles and rubella, can provide direct measures of population immunity across age groups, identify gaps in immunity, and document changes in immunity over time. Rigorously conducted, representative household serosurveys provide high-quality estimates with minimal bias. However, they can be logistically challenging, expensive, and have higher refusal rates than vaccine coverage surveys. This article shares lessons learned through implementing nine measles and rubella household serosurveys in five districts in India—the challenges faced, the potential impact on results, and recommendations to facilitate the conduct of serosurveys. Specific lessons learned arose from challenges related to community mobilization owing to lack of cooperation in certain settings and populations, limitations of outdated census information, nonresponse due to refusal or unavailability during survey enumeration and enrollment, data collection issues, and specimen collection and handling issues. Although some experiences are specific to serosurveys in India, these lessons are generalizable to other household surveys, particularly vaccination coverage and serosurveys conducted in low- and middle-income settings.

Development and Evaluation of a Fusion Polyprotein Based on HspX and Other Antigen Sequences for the Serodiagnosis of Tuberculosis

Background

The lack of suitable diagnostic tools contributes to the high prevalence of tuberculosis (TB) worldwide. Serological tests, based on multiple target antigens, represent an attractive option for diagnosis of this disease due to their rapidity, convenience, and low cost.

Methods

Measures to reduce non-specific reactions and thereby improve the specificity of serological tests were investigated, including blocking antibodies against common bacteria in serum samples and synthesizing polypeptides covering non-conserved dominant B-cell epitopes of antigens. In addition, a fusion polyprotein containing HspX and eight other antigen sequences was constructed and expressed to increase overall sensitivity of the tests.

Results

Inclusion of Escherichia coli lysate partially increased the specificity of the serological tests, while synthesis and inclusion of peptides containing non-conserved sequences of TB antigens as well as dominant B-cell epitopes reduced non-specific reactions without a decrease in sensitivity of the tests. A polyprotein fusing HspX and eight other antigen sequences was constructed and displayed 60.2% sensitivity, which was higher than that of HspX and the other individual antigen segments. Moreover, the specificity of the polyprotein was 93.8%, which was not significantly decreased when compared with HspX and the other individual antigen segments.

Conclusions

The roles of the fusion polyprotein in the humoral immune response against TB infection were demonstrated and provide a potential novel approach for the development of TB diagnostics.

Infliximab is associated with attenuated immunogenicity to BNT162b2 and ChAdOx1 nCoV-19 SARS-CoV-2 vaccines in patients with IBD

OBJECTIVE

Delayed second dose SARS-CoV-2 vaccination trades maximal effectiveness for a lower level of immunity across more of the population. We investigated whether patients with inflammatory bowel disease treated with infliximab have attenuated serological responses to a single dose of a SARS-CoV-2 vaccine.

DESIGN

Antibody responses and seroconversion rates in infliximab-treated patients (n=865) were compared with a cohort treated with vedolizumab (n=428), a gut-selective anti-integrin α4β7 monoclonal antibody. Our primary outcome was anti-SARS-CoV-2 spike (S) antibody concentrations, measured using the Elecsys anti-SARS-CoV-2 spike (S) antibody assay 3-10 weeks after vaccination, in patients without evidence of prior infection. Secondary outcomes were seroconversion rates (defined by a cut-off of 15 U/mL), and antibody responses following past infection or a second dose of the BNT162b2 vaccine.

RESULTS

Geometric mean (SD) anti-SARS-CoV-2 antibody concentrations were lower in patients treated with infliximab than vedolizumab, following BNT162b2 (6.0 U/mL (5.9) vs 28.8 U/mL (5.4) p<0.0001) and ChAdOx1 nCoV-19 (4.7 U/mL (4.9)) vs 13.8 U/mL (5.9) p<0.0001) vaccines. In our multivariable models, antibody concentrations were lower in infliximab-treated compared with vedolizumab-treated patients who received the BNT162b2 (fold change (FC) 0.29 (95% CI 0.21 to 0.40), p<0.0001) and ChAdOx1 nCoV-19 (FC 0.39 (95% CI 0.30 to 0.51), p<0.0001) vaccines. In both models, age ≥60 years, immunomodulator use, Crohn's disease and smoking were associated with lower, while non-white ethnicity was associated with higher, anti-SARS-CoV-2 antibody concentrations. Seroconversion rates after a single dose of either vaccine were higher in patients with prior SARS-CoV-2 infection and after two doses of BNT162b2 vaccine.

CONCLUSION

Infliximab is associated with attenuated immunogenicity to a single dose of the BNT162b2 and ChAdOx1 nCoV-19 SARS-CoV-2 vaccines. Vaccination after SARS-CoV-2 infection, or a second dose of vaccine, led to seroconversion in most patients. Delayed second dosing should be avoided in patients treated with infliximab.

TRIAL REGISTRATION NUMBER

ISRCTN45176516.

Development and evaluation of multi-epitope protein p72 (MeP72) for the serodiagnosis of African swine fever

African swine fever (ASF) is an acute and severe infectious disease that seriously endangers the global porcine industry. In order to develop ASF serodiagnostic reagents with high specificity and sensitivity, in the present study, the antigenic epitopes of P72 protein of African swine fever virus (ASFV) were analyzed, and the ASFV multi-epitope fusion gene MeP72 in tandem with the dominant linear epitopes was constructed. The recombinant multi-epitope fusion MeP72 (reMeP72) was prepared in Escherichia coli. A colloidal gold-based immunochromatographic assay (CGIA) based on reMeP72 was developed for the detection of antibodies against ASFV. A total of 139 pig clinical serum samples were used for assessment of the potential diagnostic value of reMeP72. The results showed that CGIA did not cross-react with positive sera of viruses, such as classical swine fever virus (CSFV), porcine circovirus type 2 (PCV2), pseudorabies virus (PRV), porcine reproductive and respiratory syndrome virus (PRRSV) and swine influenza virus (SIV), showing high specificity. Sensitivity analysis showed that CGIA could detect ASFV-positive serum at a dilution of 1:64. Compared with commercial ASFV kits, the sensitivity and specificity of ASFV CGIA based on reMeP72 protein were 85.7% and 97.6%, respectively. The agreement rate of the two methods was 96.4%, showing a good detection performance. The results indicated that the reMeP72 was of potential value for the serodiagnosis of ASF. Keywords: African swine fever virus; P72 gene; antigenic protein; colloidal gold-based immunochromatographic assay.