SUMMARY
BackgroundFactors that predict response and breakthrough phenomenon to lamivudine monotherapy in patients with HBeAg-negative chronic hepatitis B have not been well defined.
Humoral immunity has emerged as a vital immune component against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Nevertheless, a subset of recovered Coronavirus Disease-2019 (COVID-19) paucisymptomatic/asymptomatic individuals do not generate an antibody response, constituting a paradox. We assumed that immunodiagnostic assays may operate under a competitive format within the context of antigenemia, potentially explaining this phenomenon. We present a case where persistent antigenemia/viremia was documented for at least 73 days post-symptom onset using ‘in-house’ methodology, and as it progressively declined, seroconversion took place late, around day 55, supporting our hypothesis. Thus, prolonged SARS-CoV-2 antigenemia/viremia could mask humoral responses, rendering, in certain cases, the phenomenon of ‘non-responders’ a misnomer.
Viral RNA sensing triggers innate antiviral responses in humans by stimulating signaling pathways that include crucial antiviral genes such as interferon. RNA viruses have evolved strategies to inhibit or escape these mechanisms. Coronaviruses use multiple enzymes to synthesize, modify, and process their genomic RNA and sub-genomic RNAs. These include Nsp15 and Nsp16, whose respective roles in RNA capping and dsRNA degradation play a crucial role in coronavirus escape from immune surveillance. Evolutionary studies on coronaviruses demonstrate that genome expansion in Nidoviruses was promoted by the emergence of Nsp14-ExoN activity and led to the acquisition of Nsp15- and Nsp16-RNA-processing activities. In this review, we discuss the main RNA-sensing mechanisms in humans as well as recent structural, functional, and evolutionary insights into coronavirus Nsp15 and Nsp16 with a view to potential antiviral strategies.
Purpose
To investigate the presence of HPV on the ocular surface after surgical excision of HPV infected pterygia and the possible correlation of HPV with pterygium postoperative recurrence.
Materials and methods
Both exfoliative pterygium swab samples and respective tissue specimens were received and analyzed with real-time PCR for the detection of HPV-infected pterygia. In addition, swab samples from patients that had HPV-infected pterygia with no recurrence after 1 year of follow-up, as well as swab samples from patients with healthy conjunctiva, were analyzed.
Results
Forty eyes with pterygium of 40 patients and 40 eyes with normal conjunctiva were included in the study. HPV virus was detected in the tissue specimens of 11 patients (27.5%) and in the swabs of 9 patients (22.5%). The HPV subtypes detected were 33, 39, 45, 56, 59, 66, and 68. The swab test had sensitivity of 81.82% and 100% specificity. In 15 (43%) patients, a bare sclera technique was used for pterygium removal and eleven of these patients showed recurrence of the disease. Surgical excision with use of autologous conjunctival graft was performed in twenty patients and five of them had recurrence. Patients with recurrent disease were 12.41 times more likely to have an HPV-infected pterygium (p = 0.031). Furthermore, from the 11 HPV positive patients, six had no recurrence, 1 year after surgery. In five of them, a swab sample was taken from the site of the surgical excision 1 year after surgery and real-time PCR was negative for HPV presence.
Conclusion
Persistence of HPV infection seems to be correlated with postoperative pterygium recurrence. Further investigation with the use of the minimally invasive proposed swab technique may contribute in the understanding of pterygium pathogenesis and in the development of a more efficient treatment planning.
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