VACCINE RESEARCH
Year:2019 | Volume:6 | Issue:2|Papers Count:8

Introduction: Vaccination of hamsters with Schistosoma mansoni adjuvant-free recombinant cathepsin B1 (SmCB1) and L3 (SmCL3) have been shown to elicit highly significant (P < 0. 005) protection against challenge Schistosoma haematobium that was not very superior to that achieved by the cysteine peptidase, papain. Sterilizing immunity might, however, be induced if hamsters were vaccinated against S. haematobium infection with a homologous cysteine peptidase, i. e., S. haematobium cathepsin L (ShCL). Methods: Standards methods, techniques, and primers based on the published nucleotide sequence of ShCL were used to clone, amplify and express DNAs encoding the target enzyme in a bacterial expression vector. Repeat immunization trials were performed using recombinant ShCL alone or in combination with the vaccine candidate S. mansoni recombinant glyceraldehyde 3-phosphate dehydrogenase, in parallel with S. mansoni lecucine aminopeptidase. Results: The results together indicated that our adjuvant-free, cysteine peptidase-based vaccine elicits highly significant (P < 0. 0001) reduction in challenge worm burden and parasite egg viability. Protection was associated with whole blood cultures release of type 1, type 2, and type 17 cytokines, and modest, yet significant (P < 0. 05) humoral response to ShCL. Conclusion: Sterilizing immunity was, however, not achieved in any trial, likely because of the preponderant role of cysteine peptidasesinduced nonspecific factors in amplifying and antagonizing its protective potential. Experiments are planned in an aim to identify these elusive factors and their exact role.

The amount of multidrug-resistant (MDR) strains, especially methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis, as frequent causes of nosocomial and device-related infections have increased. Biofilm formation is an essential requisite in staphylococcal pathogenicity. It is considered as a bacterial surveillance, antibiotic resistance, and transition of antibiotic resistance genes factor. Therefore, biofilm-related macromolecules have been suggested as putative new vaccine candidates to combat staphylococcal infections. Based on the MEDLINE and Google scholar databases, some Staphylococci macromolecules are involved in the biofilm formation process and have been reviewed as putative vaccines. Based on experiments, common staphylococcus antigens could prevent the progress of the caused diseases by this genus. Moreover, considering related stages in biofilm formation, a multivalent putative vaccine (protein and polysaccharide) candidate could be enhancing the eradication chance of aforementioned bacterial families.

Since the reemergence of a severe acute respiratory syndrome caused by a novel coronavirus (SARS-CoV-2), the disease caused by this virus, known as COVID-19, has been spreading rapidly all around the world. As of early June 2020, COVID-19 has infected more that 6. 6 million people, and has caused more than 390, 000 deaths, globally. Similar to its pioneers, namely SARS-CoV and MERS-CoV, there is currently no vaccine or specific antiviral treatment against this virus. This review provides a timely overview on efforts as well as different platforms used for developing an effective vaccine against COVID-19.

Introduction: Inactivated Infectious Bursal Disease Virus (IBDV) is administrated against Infectious Bursal Disease (IBD). Chitosan biopolymer is capable of inducing proper immune responses to an antigen while being non-toxic and degradable. In this study, the effect of chitosan on improving the humoral immune responses against IBD virus (IBDV) was investigated. Methods: The antigen was prepared by inoculating IBDV in embryonated chicken eggs and inactivation by ethylenimine. Chitosan solutions at final concentrations of 0. 5% and 1% were made and used as an adjuvant. One-day-old chickens were randomly divided in 8 groups and received intramuscularly different profiles of the inactivated antigen and chitosan solution. Serum samples were collected before the prime and booster injection as well as at the defined intervals and assayed by ELISA and serum neutralization tests. Results: After 2-dose intramuscular immunization with inactivated IBDV in combination with chitosan, significant increases (P < 0. 05) in antibody titers were observed compared with other administration groups. The addition of 1% chitosan to inactivated IBDV resulted in higher level of neutralizing antibody titer than 0. 5% chitosan. However, the difference in the enhancing of antibody titers and the neutralization index between these concentrations was not significant. Conclusion: These data revealed that chitosan as an antigen carrier has the potential to enhance specific immune responses induced by inactived IBDV.

The field of HIV vaccines received a “ boost” with around 30% protection obtained in the RV144 randomized, double-blind, efficacy trial in Thailand. Currently, 560 clinical trials in HIV vaccine development are registered as complete and results are expected from several of these studies. The modest success attained at this time may be attributed to early attempts at identifying an animal model to test vaccine efficacy. Macaque models of HIV-1 infection have revealed viral infection, transmission, pathogenesis, and prevention. Identification of simian immunodeficiency virus (SIV) and its related strains served as the macaque counterpart of HIV and through genetic engineering, enabled chimera development that explored how macaques respond to a human antigen as well. Along with understanding viral infection, it is worth exploring the genetic repertoire of macaques for determining how the major histocompatibility complex and anti-retroviral restriction factors offer barriers to viral replication.

Introduction: Streptococcus pneumoniae causes invasive and non-invasive diseases in children and adults. Currently, there are two types of pneumococcal vaccines: 23-valent pneumococcal polysaccharide vaccine and 13-valent pneumococcal conjugate vaccine which have caused many failures. Therefore, a new generation of pneumococcal vaccines is being pursued. Methods: An improved version of our previous study was performed using recombinant C-terminal of pneumococcal polyhistidine triad protein D (PhtD-C) as a vaccine antigen. The antigen was combined with meningococcal outer membrane vesicle (OMV) and alum as adjuvants to immunize BALB/c mice intraperitoneally. The generated total IgG, specific IgG, IgG1 and IgG2a antibodies and the killing ability of pneumococci by an opsonophagocytosis assay were then assayed. Results: Immunization by 30 μ g PhtD-C and 50 μ g OMV as an adjuvant, induced higher amounts of functional antibodies compared to our previous study while killing 50-55% of pneumococci cells. Conclusion: At optimized concentrations, PhtD-C and meningococcal OMV could be considered as a potent immunogens and the induced specific IgGs were effective and functional for killing pneumococci.

Introduction: Control efforts of visceral leishmaniasis (VL) are hindered due to inappropriate early case detection of Leishmania infection with varying degree of susceptibility to develop the disease. Methods: We assessed the current infection status using Leishmanin skin test (LST) and direct agglutination test (DAT) in a cohort population (206 randomly selected individuals) in a VL endemic area of Bihar, India. Results: Cellular immunity was revealed in 18. 4% and antibody response in 18. 9% of the population. The age-group of 20-29 years were most vulnerable. DAT titer was inversely proportional to duration of past history of VL. The houses having present or past history of kala-azar in family were observed with high Leishmanin and DAT positivity, indicating relevance of household contacts in the disease transmission. Conclusion: The reactivity of both LST and DAT tests may help in identifying the possible groups with varying degree of susceptibility and risk of infection or having prior exposure to the leishmania infection with or without development of the disease.

Introduction: Exposure to the microgravity environment could cause human physiological abnormalities that include fluid shift, anemia, osteoporosis, immunosuppression, etc. Monocytes and macrophages are important components of the immune system and could serve as precursors of osteoclasts. A direct effect of microgravity on monocytes and/or macrophages may contribute to immunosuppression and osteoporosis. Methods: To test this hypothesis, we reviewed the studies concerning the direct effects of microgravity on the monocyte/macrophage physiology and discussed the links of these effects to the human physiological abnormalities caused by microgravity. Results: Inhibited development and proliferation, reduced production of reactive oxygen species and proinflammatory cytokines and inhibited cell locomotion were observed in monocyte/macrophages under microgravity. These microgravity effects may lead to immunosuppression. Enhanced osteoclastogenesis was observed in monocyte/macrophages under microgravity. This microgravity effect may lead to osteoporosis. The molecular mechanisms underlying these microgravity effects were also presented. For example, the mechanisms of the inhibited cell locomotion under microgravity include: reduced β-actin expression, abnormality in the structure of focal adhesions and impaired protein kinase C signaling. Conclusion: The elucidation of the molecular mechanisms by which microgravity interferes with the monocyte/macrophage physiology may favor the identification of potential drug targets to reverse the deleterious effects of microgravity. Furthermore, due to the fact that macrophages are professional antigen-presenting cells, we propose that microgravity might modulate the efficacy of antigen presentation by macrophages in the immune response to vaccines.