Analysis of Hepatitis D Virus in Minor Salivary Gland of Sjögren's Disease

Hepatitis C Virus as a Possible Helper Virus in Human Hepatitis Delta Virus Infection

Previous studies reported that the hepatitis C virus (HCV) could help disseminate the hepatitis D virus (HDV) in vivo through hepatitis B virus (HBV)-unrelated ways, but with essentially inconclusive results. To try to shed light on this still-debated topic, 146 anti-HCV-positive subjects (of whom 91 HCV/HIV co-infected, and 43 with prior HCV eradication) were screened for anti-HDV antibodies (anti-HD), after careful selection for negativity to any serologic or virologic marker of current or past HBV infection. One single HCV/HIV co-infected patient (0.7%) tested highly positive for anti-HD, but with no positive HDV-RNA. Her husband, in turn, was a HCV/HIV co-infected subject with a previous contact with HBV. While conducting a thorough review of the relevant literature, the authors attempted to exhaustively describe the medical history of both the anti-HD-positive patient and her partner, believing it to be the key to dissecting the possible complex mechanisms of HDV transmission from one subject to another, and speculating that in the present case, it may have been HCV itself that behaved as an HDV helper virus. In conclusion, this preliminary research, while needing further validation in large prospective studies, provided some further evidence of a role of HCV in HDV dissemination in humans.

Highlights from the 2023 International Meeting on the Molecular Biology of Hepatitis B virus

Since its discovery in 1965, our understanding of the hepatitis B virus (HBV) replication cycle and host immune responses has increased markedly. In contrast, our knowledge of the molecular biology of hepatitis delta virus (HDV), which is associated with more severe liver disease, is less well understood. Despite the progress made, critical gaps remain in our knowledge of HBV and HDV replication and the mechanisms underlying viral persistence and evasion of host immunity. The International HBV Meeting is the leading annual scientific meeting for presenting the latest advances in HBV and HDV molecular virology, immunology, and epidemiology. In 2023, the annual scientific meeting was held in Kobe, Japan and this review summarises some of the advances presented at the Meeting and lists gaps in our knowledge that may facilitate the development of new therapies.

Salivary Glands and Viral Pathogenesis

The oral cavity is an epidemiologically relevant route of viral transmission due to the shedding of viruses in saliva. With advancements in salivary diagnostics, an increasing number of viruses have been detected. However, the anatomic source of virus in saliva is still largely unknown. Some viruses have a well-established tropism for the salivary glands (SGs), and recent studies have emphasized the importance of the glands as potential reservoirs for infectious viruses. Viral infections of the SGs have been linked to acute and chronic SG pathology and may be associated with SG dysfunction, with phenotypes similar to those seen in SjÖgren's disease (SjD), an autoimmune condition that affects the salivary and lacrimal glands. Understanding the breadth of viruses that infect the SG and the conserved or distinct host responses to these infections may provide insights into the pathogenesis of virus-mediated SG diseases. There is a need for further research to fully understand the molecular mechanisms by which viruses enter and replicate in the glands, their physiologic impact on SG function, and whether the SGs can serve as a long-term reservoir for infectious viral particles. The purpose of this review is to highlight a group of viruses that infect the salivary gland: hepatitis C virus, hepatitis D virus, severe acute respiratory syndrome coronavirus 2, enteric viruses, human T-cell leukemia virus type I, human immunodeficiency virus, human cytomegalovirus, and BK polyomavirus. We focus on the effects of viral infection on salivary gland (SG) inflammation, function, and its association with SjD.