No abstract

Viral hepatitis ranks as the fifth cause of morbidity for infectious diseases in Cuba. Epidemics are observed frequently in the population, the hepatitis A virus being the main agent responsible for such epidemics. Previous reports also confirmed the circulation of the hepatitis E virus. From 1998 to 2003, 258 serum samples were collected by the Reference Laboratory on Viral Hepatitis during 33 outbreaks of acute viral hepatitis as well as from 39 sporadic clinical cases. Sera were tested for anti-HAV and anti-HEV IgM by EIA. Overall of the 33 outbreaks studied sera from 12 (36.4%) were positive for anti-HAV IgM only, from 7 (21.2%) were positive for anti-HEV IgM only, and from 14 (42.4%) were positive for antibodies to both viruses. Individually of the 258 sera collected, 137 (53.1%) were positives for anti-HAV IgM, 20 (7.8%) were positives for anti-HEV IgM, 33 (12.8%) were positives for both markers and 68 (26.4%) were negative to both. Of the clinical cases, 4 (10.3%) were positives for anti-HAV IgM, 13 (33.3%) were positives for anti-HEV IgM and 5 (12.8%) were positives for both markers. Seventeen (43.6%) sera were negatives for all viral hepatitis markers available (A-E). A high positivity for HEV was found in outbreaks tested with the kit produced by CIGB. In particular HEV seems to infect individuals of all ages. The results demonstrate the co-circulation of and co-infection with two enterically transmitted viruses; however a higher positivity was observed for anti-HAV than to anti-HEV (53.1% vs. 7.8%) in outbreaks.

No abstract

COVID-19 is a respiratory viral disease caused by a new coronavirus called SARS-CoV-2. This disease has spread rapidly worldwide with a high rate of morbidity and mortality. The receptor-binding domain (RBD) of protein spike (S) mediates the attachment of the virus to the host’s cellular receptor. The RBD domain constitutes a very attractive target for subunit vaccine development due to its ability to induce a neutralizing antibody response against the virus. With the aim of boosting the immunogenicity of RBD, it was fused to the extracellular domain of CD154, an immune system modulator molecule. To obtain the chimeric protein, stable transduction of HEK-293 was carried out with recombinant lentivirus and polyclonal populations and cell clones were obtained. RBD-CD was purified from culture supernatant and further characterized by several techniques. RBD-CD immunogenicity evaluated in mice and non-human primates (NHP) indicated that recombinant protein was able to induce a specific and high IgG response after two doses. NHP sera also neutralize SARS-CoV-2 infection of Vero E6 cells. RBD-CD could improve the current vaccines against COVID-19, based in the enhancement of the host humoral and cellular response. Further experiments are necessary to confirm the utility of RBD-CD as a prophylactic vaccine and/or booster purpose.

Since the beginning of the COVID-19 pandemic, the development of effective vaccines against this pathogen has been a priority for the scientific community. Several strategies have been developed including vaccines based on recombinant viral protein fragments. The receptor-binding domain (RBD) in the S1 subunit of S protein has been considered one of the main targets of neutralizing antibodies. In this study we assess the potential of a vaccine formulation based on the recombinant RBD domain of SARS-CoV-2 expressed in the thermophilic filamentous fungal strain Thermothelomyces heterothallica and the hepatitis B virus (HBV) core protein. Functional humoral and cellular immune responses were detected in mice. To our knowledge, this is the first report on the immune evaluation of a biomedical product obtained in the fungal strain T. heterothallica. These results together with the intrinsic advantages of this expression platform support its use for the development of biotechnology products for medical purpose.