The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has had a tremendous impact on health services; hundreds of thousands of healthcare workers (HCWs) have died from coronavirus disease 2019 (COVID-19). The introduction of the BNT162b2 mRNA vaccine in Italy provided recipients with significant protection against COVID-19 within one to two weeks after the administration of the second of the two recommended doses. While the vaccine induces a robust T cell response, the protective role of factors and pathways other than those related to memory B cell responses to specific SARS-CoV-2 antigens remains unclear. This retrospective study aimed to evaluate the determinants of serological protection in a group of vaccinated HCWs (N = 793) by evaluating circulating levels of antiviral spike receptor-binding domain (S-RBD) antibodies during the nine-month period following vaccination. We found that 99.5% of the HCWs who received the two doses of the BNT162b2 vaccine developed protective antibodies that were maintained at detectable levels for as long as 250 days after the second dose of the vaccine. Multivariate analysis was performed on anti-S-RBD titers in a subgroup of participants (n = 173) that were evaluated twice during this period. The results of this analysis reveal that the antibody titer observed at the second time point was significantly related to the magnitude of the primary response, the time that had elapsed between the first and the second evaluation, and a previous history of SARS-CoV-2 infection. Of importance is the finding that despite waning antibody titers following vaccination, none of the study participants contracted severe COVID-19 during the observational period.
The new Abbott RealTime hepatitis B virus (HBV) assay was compared to the Cobas AmpliPrep/CobasTaqMan assay with 128 serum samples from patients with chronic hepatitis B. There was an excellent correlation (r ؍ 0.961) between the two assays, with the Abbott RealTime test showing at least equivalent sensitivity and a slightly wider dynamic range than the Cobas TaqMan assay. By coupling high sensitivity with a large dynamic range, the Abbott RealTime HBV assay is useful in monitoring the response to antiviral therapy.Hepatitis B virus (HBV) is a small partially double-stranded virus belonging to the family of the Hepadnaviridae that can cause acute or chronic hepatitis (2). Millions of people around the world are infected by HBV, and it is estimated that about 350 million people worldwide have developed a persistent infection (6). Measurement of HBV levels in serum is a reliable marker for prognosis of acute and chronic infection and plays an important role in the management of patients receiving antiviral drugs (7,8). Therefore, diagnostic assays for the accurate quantitation of HBV DNA are essential for optimal patient management. Monitoring of HBV DNA allows to predict the success of antiviral therapy and to identify the development of drug resistance. Real-time PCR is a new molecular tool that is progressively replacing endpoint PCR systems for monitoring patients with chronic hepatitis B since it allows for high sensitivity, a broad dynamic range, accuracy, and rapid results (1, 9).Quantification by real-time PCR is based on the determination of the threshold cycle (C T ) when the amplified product is detected for the first time (4) and the PCR is still in the exponential phase. In this case the quantification of the viral load is much more accurate and reliable than that measured with endpoint PCR systems (3).The aim of our study was to evaluate the Abbott RealTime HBV assay for the detection and quantification of HBV-DNA in serum samples and to compare these results with those obtained using the Cobas AmpliPrep/Cobas TaqMan HBV test (Roche Diagnostics). The study was carried out on 128 serum samples collected from patients with chronic HBV infections attending our hepatology clinic at the University Hospital Tor Vergata, Rome, Italy.Blood samples were collected in a BD Vacutainer tube containing a separation gel. After centrifugation, the serum was divided into two aliquots of 1 ml each and tested by the Abbott and Cobas TaqMan Real-time PCR assays, respectively. Both systems use a hybridization probe with a fluorescent moiety covalently linked to the 5Ј end of the probe (reporter) and a quenching moiety bound to the 3Ј end of the probe (quencher). In the presence of target, probe hybridization and primer extension occur simultaneously. The fluorescent signal is generated by removing the reporter through the 5Ј33Ј exonuclease activity of a thermostable Taq DNA polymerase (4, 5). In the TaqMan and Abbott RealTime PCR assays an additional probe is used to detect genotype G or C, respectively. While the Coba...
Our results show that the chances of development of resistance are far lower in M/M than in lymphocytes. This underlines the importance and the peculiar role of M/M as reservoirs of either wild-type or resistant strains in human organs.
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