Noroviruses commonly cause infectious gastroenteritis and massive food poisoning. There is an urgent need to elucidate the infection mechanism of noroviruses and to develop vaccines and therapeutic drugs. In addition to human disease, noroviruses have been implicated in animal disease. Noroviruses that cause murine diseases can be propagated in strained cultured cells, and for many years, murine norovirus has been used as a model for human noroviruses that could not be propagated in cultured cells. That model and advances in technology have been instrumental in basic studies of noroviruses. From structural biology, noroviruses undergo dynamic shape changes to improve their infectivity when they infect cells. New culture techniques have made human intestinal organoids available for studying the mechanisms of pathogenic expression of human noroviruses in the intestinal tract, mechanisms of infection growth, and the search for receptor molecules. Vaccines and antivirals using human intestinal organoids are under active development, and some are already in clinical trials. In this paper, I review the latest research results, vaccine development, and other advances from the history of norovirus discovery.
The 2020 Nobel Prize in Physiology or Medicine was awarded to three researchers who contributed to the development of the disease concept ''non-A, non-B hepatitis'' and the isolation of its causative agent, hepatitis C virus (HCV). Technologies and experimental systems to analyze HCV have been greatly improved for these three decades, and the antiviral treatments against HCV have been developed. This review summarizes the effort to elucidate the HCV biology so far and the remaining subject to be solved in the future. I also introduce the studies to identify bioactive natural products by taking advantage of the HCV infection cell culture system.
Recent development of hepatitis B virus (HBV) culture systems has proceeded the molecular virological studies of the life cycle of HBV including infection step. However, the reproduction of HBV life cycle under the more physiological condition may be required to know the nature of HBV more precisely. The HBV culture system, we recently developed using immortalized human hepatocytes cultured in the three dimensional condition, seemed to be one of good tools for that purpose.
Since the first case of COVID-19 was reported from Wuhan, China in December 2019, SARS-CoV-2 has been spreading globally and has become major public health concern. At present, development of specific treatment for COVID-19 is in progress and several countermeasures have been subjected to clinical trials. However, efficacy of these countermeasures is limited. For development of effective medicines or vaccines against infectious diseases, it is mandatory to elucidate its etiology and pathogenesis by means of pathological analysis. Pathological studies revealed that the COVID-19 mainly affects respiratory tracts although other organs are also involved. In addition, immunological studies demonstrated that host immune response may exacerbates COVID-19 through systemic inflammation. In this review, we would like to overview pathology and immunology of COVID-19.
Chronic kidney disease of unknown etiology (CKDu) has emerged in endemic areas of Sri Lanka since the 1990s. The disease is a chronic but fatal disease. Until now, heavy metals and agrochemicals have been suspected as the cause of CKDu, but it has been still unknown. Recently, we have found a high seroprevalence to hantavirus in CKDu patients and reported that hantavirus infection is a risk of CKDu. Hantaviruses are rodent-borne zoonotic viruses. Here, I would like to introduce a story of the research from sero-epidemiology to the search for host animals.