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Order Amarillovirales
Published in Paul Pumpens, Peter Pushko, Philippe Le Mercier, Virus-Like Particles, 2022
Paul Pumpens, Peter Pushko, Philippe Le Mercier
The Amarillovirales order currently involves one family, namely Flaviviridae, 4 genera, and 89 species. The genera are Flavivirus, Hepacivirus, Pegivirus, and Pestivirus. Most infect mammals and birds. Many of them are host-specific and highly pathogenic, such as hepatitis C virus (HCV) of the genus Hepacivirus. After HCV, a major human pathogen-causing progressive liver disease (Yu ML and Chuang 2021), the Hepacivirus genus involves several other viruses of unknown pathogenicity that infect horses, rodents, bats, cows, and primates (Scheel et al. 2015).
Classification of Hemorrhagic Fevers
Published in James H. S. Gear, CRC Handbook of Viral and Rickettsial Hemorrhagic Fevers, 2019
The name Togavirus refers to the envelope and is derived from the Latin ‘toga’ — a Roman mantle or cloak. The family Togaviridae now comprises four genera, namely, Alphavirus with 26 species, Rubivirus (one species), Pestivirus (three species), and Arterivirus (one species). The virions are spherical, 40 to 70 nm in diameter, and mature by budding of nucleocapsids through plasma membranes. The virus envelope carries surface projections associated with two proteins, El and E2, that are usually glycosylated. El is the functional hemagglutinin for Alphaviruses. The envelope encloses the spherical nucleocapsid (diameter 28 to 35 nm) with icosohedral symmetry. The genome is a single molecule of single-stranded RNA with a molecular weight of about 4 × 106. The gene sequence of the Alphavirus genus has been determined.
Role of structural disorder in the multi-functionality of flavivirus proteins
Published in Expert Review of Proteomics, 2022
Shivani Krishna Kapuganti, Aparna Bhardwaj, Prateek Kumar, Taniya Bhardwaj, Namyashree Nayak, Vladimir N. Uversky, Rajanish Giri
The viruses under the family Flaviviridae are enveloped with positive-sense single-stranded, non-segmented RNA genome ranging from 9 to 13kb. Mostly, the viruses are pathogenic to humans and their pathogenicity ranges from asymptomatic/mild symptoms to lethal hemorrhagic and neurological damages. This family is further classified into four genera: Flavivirus, Hepacivirus, Pegivirus, and Pestivirus, having 53, 14, 11, and 11 species, respectively. Some of the well-known examples of flaviviruses are Dengue virus (DENV), Japanese encephalitis virus (JEV), Tick-borne encephalitis virus (TBEV), West Nile virus (WNV), Yellow fever virus (YFV), and Zika virus (ZIKV) from Flaviviruses.
Virus analog decreases estradiol secretion in FSH-treated human ovarian granulosa cells
Published in Gynecological Endocrinology, 2020
Yuying Fang, Bo Wang, Shiming Lyu, Kemei Zhang, Qi Cheng, Yimin Zhu
Estradiol is produced by GC aromatization of theca-derived androgens which is regulated by the stimulation of gonadotrophins [23]. In human granulosa cells, FSH directly stimulate mitosis [24]. Furthermore, FSH is a key activator for E2 synthesis, which dramatically upregulates the expression of aromatase. Although the viability of GCs was not affected by Poly (I: C), the concentration of E2 in the supernatant of FSH and Poly (I: C) treated GCs significantly decreased compared with that treated by FSH alone. This indicates that the synthesis of E2 significantly decreased after treated by Poly (I: C). We further found that Poly (I: C) did not change the expression of aromatase in control GCs, but it inhibited the expression of aromatase in FSH-treated GCs. FSH in the culture system mimics the follicular phase of ovarian cycle. Given that aromatase is the key enzyme for E2 synthesis, we concluded that E2 reduction was resulting from aromatase inhibiting. In addition, we have detected a significant increase in IL-6 level in culture supernatants of GCs treated with Poly (I: C) (Supplementary Materials, Figure S3). IL-6 has been proved to inhibit estrogen synthesis [25]. From a clinical point of view, inhibition of E2 synthesis would lead to decreased concentration of plasma E2. Compromised E2, LH, P concentration induced by pestivirus infection had been reported in superovulated cattle [26]. During the late follicular phase, decreased E2 affects the positive feedback of estrogen and delays luteinizing hormone (LH) surge. Subsequently, it might lead to follicular atresia or luteal phase defect [26–28]. Decreased E2 may also cause endometrial hypoplasia and compromise the receptivity of endometrium.