China
Africa
Explore chapters and articles related to this topic
The Viruses
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Hepatitis B surface antigen, (HBsAg) is the common antigen on the surface of each form of the virus particles. HBsAg is found in great excess in infected subjects and therefore is used in diagnostic tests for the virus infection. The major structural core protein (C protein or hepatitis B core antigen) is a 21 kD basic phosphoprotein that contains viral DNA and a polymerase called P protein. The pre-S1-region of the viral genome encodes the L protein. This protein is a minor component of proteins produced, but is an important component of the infectious Dane particle and is important in virus assembly. L proteins are thought to contain receptor recognition domains. The S protein makes up the majority of the HBsAg and is produced in abundance.
Hepatitis B
Published in Vincenzo Berghella, Maternal-Fetal Evidence Based Guidelines, 2022
Laura Felder, Zimeng Gao, Danielle Tholey
Exposure to HB in pregnancy: Check all labs as discussed previously (see Table 32.1). If HBsAg– and HBsAb–, give HBIg and begin the HBV vaccine series (preferably within 24 hours of exposure): This combination will prevent 75% of transmission [27]. Must give HBIg within 14 days of sexual contact. Repeat HBIg within one month if blood or mucous membrane exposure [27].
Viral hepatitis in pregnancy
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
If negative, the pregnant mother who is at risk for hepatitis B infection (unsafe sex, multiple sexual partners, health-care workers, active intravenous drug user, etc.) should be vaccinated. The limited data we have indicate that there is no apparent risk for adverse events to developing fetuses. Current vaccines contain noninfectious HBsAg and should cause no risk to the fetus.
Developments in pharmacotherapeutic agents for hepatitis B – how close are we to a functional cure?
Published in Expert Opinion on Pharmacotherapy, 2023
Naoshin Khan, Mohamed Ramzi Almajed, Mary Grace Fitzmaurice, Syed-Mohammed Jafri
Functional cure of HBV requires a multisystemic approach that includes inhibition of replication, HBsAg reduction, and immune stimulation. Currently, entry inhibitors, NA, and CAMs result in sufficient HBV DNA reduction. As mentioned prior, studies have shown the combination of these agents such as vebicorvir with ETV resulted in marked reduction of viral replication, but HBsAg loss was not demonstrated. Hence, direct antiviral therapies such as siRNAs, ASO, NAP, and STOP are additional therapies to consider in HBsAg seroconversion. ASO such as bepirovirsen has shown to decrease both HBsAg and HBV DNA while siRNAs such as VIR-2218 with IFN therapy led to substantial reduction as well. Immunomodulators such as therapeutic vaccines can further result in HBsAg loss, especially with developing agents such as HeberNasvac. These newer therapies have been studied in the setting of approved agents such as IFN and NA but not in combination with one another. By adding these agents and observing therapy over a finite period, sustained viral reduction with HBsAg can hopefully be achieved.
Besifovir dipivoxil maleate: a novel antiviral agent with low toxicity and high genetic barriers for chronic hepatitis B
Published in Expert Opinion on Pharmacotherapy, 2021
In the era of antiviral therapy, functional cure defined as sustained loss of HBsAg is uncommon. Therefore, life-long antiviral therapy is needed in CHB patients. The potential side effects of long-term antiviral therapy are a concern, especially long-term use of TDF causing nephrotoxicity and bone mineral density (BMD) loss. Based on the results of a 192-week phase 3 extension study, BSV demonstrated overall safety in terms of bone and renal impairment [18]. At week 48 of a phase 3 study comparing BSV with TDF, BMD and estimated glomerular filtration rate (eGFR) were significantly decreased in the TDF group, but unchanged in the BSV group. After switching from TDF to BSV, BMD and eGFR recovered to a similar degree to the BSV-BSV group, and there was no significant difference up to 192 weeks. The changes from baseline in BMD and eGFR during the study period are summarized in Table 3.
Demystifying particle-based oral vaccines
Published in Expert Opinion on Drug Delivery, 2021
Pedro Gonzalez-Cruz, Harvinder Singh Gill
Although oral vaccines against many different diseases have been investigated (Figure 1B), most antigens fall into the model antigen category. These model antigens comprise OVA, bovine serum albumin (BSA), and human serum albumin (HSA). These well-documented antigens are readily available, and this has led to their extensive use in testing new delivery systems. The top 5 diseases (besides model proteins [22–41]) researched with particle-based oral delivery systems are hepatitis B [42–49], cholera [50–56], norovirus [57–64], diphtheria [65–71], and E. coli infection [9,72–77] (Figure 1B). Hepatitis B surface antigen (HBsAg) is the second most common disease investigated to make an oral vaccine. If successful, this could be a valuable oral vaccine since about 250 million people worldwide are infected with Hepatitis B, and it is the leading cause of liver cancer [78]. To carry out the in vivo studies, mice are the most commonly used species, and in particular, most articles have used BALB/c mice followed by C57BL/6 mice (Figure 1C) [9,51,54,57,58,60,66,67,70,73,79–109]. Rats, rabbits, cattle, pigs, macaques, and guniea pigs have also been used as animal models. Three human studies have been performed, and they have investigated vaccines against diphtheria and norovirus diseases [61,63,68].