Toxoplasma gondii is the causative agent for toxoplasmosis. The rhoptry protein 1 (ROP1) is secreted by rhoptry, an apical secretory organelle of the parasite. ROP1 plays an important role in host cell invasion. In this study, the efficacy of ROP1 as a vaccine candidate against toxoplasmosis was evaluated through intramuscular or subcutaneous injection of BALB/c mice followed by immunological characterization (humoral- and cellular-mediated) and lethal challenge against virulent T. gondii RH strain in BALB/c mice. Briefly, a recombinant DNA plasmid (pVAX1-GFP-ROP1) was expressed in CHO cells while expression of recombinant ROP1 protein (rROP1) was carried out in Escherichia coli expression system. Immunization study involved injection of the recombinant pVAX1-ROP1 and purified rROP1 into different group of mice. Empty vector and PBS served as two different types of negative controls. Results obtained demonstrated that ROP1 is an immunogenic antigen that induced humoral immune response whereby detection of a protein band with expected size of 43 kDa was observed against vaccinated mice sera through western blot analysis. ROP1 antigen was shown to elicit cellular-mediated immunity as well whereby stimulated splenocytes with total lysate antigen (TLA) and rROP1 from pVAX1-ROP1 and rROP1-immunized mice, respectively, readily proliferated and secreted large amount of IFN-γ (712 ± 28.1 pg/ml and 1457 ± 31.19 pg/ml, respectively) and relatively low IL-4 level (94 ± 14.5 pg/ml and 186 ± 14.17 pg/ml, respectively). These phenomena suggested that Th1-favored immunity was being induced. Vaccination with ROP1 antigen was able to provide partial protection in the vaccinated mice against lethal challenge with virulent RH strain of tachyzoites. These findings proposed that the ROP1 antigen is a potential candidate for the development of vaccine against toxoplasmosis.
Objective: To present the report from the Kuwait National Primary Immunodeficiency Registry between 2004 and 2018. Methods: The patients were followed prospectively between January 2004 and December 2018 and their collected data included sociodemographic, diagnosis, clinical presentation, laboratory tests, and treatment. Results: A total of 314 PID patients (165 males and 149 females) were registered during the study period. Most of the patients (n = 287, 91.4%) were Kuwaiti nationals and the prevalence among Kuwaitis was 20.27/100,000 with a cumulative incidence of 24.96/100,000 Kuwaitis. The distribution of the patients according to PID categories was as follow: immunodeficiencies affecting cellular and humoral immunity, 100 patients (31.8%); combined immunodeficiencies with associated syndromic features, 68 patients (21.7%); predominantly antibody deficiencies, 56 patients (17.8%); diseases of immune dysregulation, 47 patients (15%); congenital defects of phagocyte number or function, 20 patients (6.4%); autoinflammatory disorders, 1 patient (0.3%); and complement deficiencies, 22 patients (7%). The mean age of the patients at onset of symptoms was 26 months while the mean age at diagnosis was 53 months and the mean delay in diagnosis was 27 months. Most of the patients (n = 272, 86%) had onset of symptoms before the age of 5 years. Parental consanguinity rate within the registered patients was 78% and a positive family history of PID was noticed in 50% of the patients. Genetic testing was performed in 69% of the patients with an overall diagnostic yield of 90%. Mutations were identified in 46 different genes and more than 90% of the reported genetic defects were transmitted by an autosomal recessive pattern. Intravenous immunoglobulins and stem cell transplantation were used in 58% and 25% of the patients, respectively. There were 81 deaths (26%) among the registered patients with a mean age of death of 25 months. Conclusions: PID is not infrequent in Kuwait and the reported prevalence is the highest in the literature with increased proportion of more severe forms. Collaborative efforts including introduction of newborn screening should be implemented to diagnose such cases earlier and improve the quality of life and prevent premature deaths.
Objectives: To present a prospective report on the characteristics of autoimmune manifestations in patients with primary immunodeficient children registered in the Kuwait National PIDs Registry (KNPIDR). Methods: The data were obtained from the Kuwait National Primary Immunodeficiency Disorders Registry during the period of January 2004 to December 2019. Results: A total of 286 PID children were registered in KNPIDR during the study period with a predominance of immunodeficiencies affecting cellular and humoral immunity followed by combined immunodeficiencies with associated syndromic features and diseases of immune dysregulation. Fifty-seven (19.9%) patients presented with a total of 107 autoimmune manifestations. There was no significant statistical association between autoimmune manifestations and gender. Patients with autoimmune manifestations were older at onset of PID symptoms compared to those with no such manifestations, but this did not reach level of significance. The diagnosis delay was longer in patients with autoimmune manifestations compared to those with no such manifestations (p = 0.038). Forty-seven percent of these manifestations were among the presenting symptoms while 53% were documented later during the course of the disease. Fifty-seven percent of the patients developed 1 autoimmune manifestation, 30% developed 2 such manifestations, and 16% had ≥3 autoimmune manifestations. The most common autoimmune manifestation was cytopenia, followed by gastrointestinal manifestations and manifestations of the skin, hair, and nails. Autoimmune cytopenia were more common in patients with immune dysregulation syndromes, while gastrointestinal and skin manifestations predominate in patients with immunodeficiencies affecting cellular and humoral immunity and endocrine manifestations were more common in immune dysregulation syndromes. There were significant statistical associations between developing autoimmune manifestations and death as well as PID categories, being more common in patients with immune dysregulation. The frequency of autoimmunity was high among patients with RAG, WAS, STAT5b, NF-κB2, Fas, FasL, LRBA, APECED, IL-10, and C4 deficiencies. Conclusions: Autoimmunity is frequent in patients with PIDs in Kuwait. This should prompt the suspicion of a PID in patients who present initially with autoimmunity, especially autoimmune cytopenia. Such patients should be managed with extra care since they are at a higher risk of death.
Cryptosporidiosis is a gastrointestinal illness caused by the protozoan parasite Cryptosporidium species, which is a leading cause of diarrhea in a variety of vertebrate hosts. The primary mode of transmission is through oral routes; infections spread with the ingestion of oocysts by susceptible animals or humans. In humans, Cryptosporidium infections are commonly found in children and immunocompromised individuals. The small intestine is the most common primary site of infection in humans while extraintestinal cryptosporidiosis occurs in immunocompromised individuals affecting the biliary tract, lungs, or pancreas. Both innate and adaptive immune responses play a critical role in parasite clearance as evident from studies with experimental infection in mice. However, the cellular immune responses induced during human infections are poorly understood. In this article, we review the currently available information with regard to epidemiology, diagnosis, therapeutic interventions, and strategies being used to control cryptosporidiosis infection. Since cryptosporidiosis may spread through zoonotic mode, we emphasis on more epidemiological surveillance-based studies in developing countries with poor sanitation and hygiene. These epidemiological surveys must incorporate fecal source tracking measures to identify animal and human populations contributing significantly to the fecal burden in the community, as mitigation measures differ by host type.
Dengue is a major public health concern, affecting almost 400 million people worldwide, with about 70% of the global burden of disease in Asia. Despite revised clinical classifications of dengue infections by the World Health Organization, the wide spectrum of the manifestations of dengue illness continues to pose challenges in diagnosis and patient management for clinicians. When the Zika epidemic spread through the American continent and then later to Africa and Asia in 2015, researchers compared the characteristics of the Zika infection to Dengue, considering both these viruses were transmitted primarily through the same vector, the Aedes aegypti female mosquitoes. An important difference to note, however, was that the Zika epidemic diffused in a shorter time span compared to the persisting feature of Dengue infections, which is endemic in many Asian countries. As the pathogenesis of viral illnesses is affected by host immune responses, various immune modulators have been proposed as biomarkers to predict the risk of the disease progression to a severe form, at a much earlier stage of the illness. However, the findings for most biomarkers are highly discrepant between studies. Meanwhile, the cross-reactivity of CD8+ and CD4+ T cells response to Dengue and Zika viruses provide important clues for further development of potential treatments. This review discusses similarities between Dengue and Zika infections, comparing their disease transmissions and vectors involved, and both the innate and adaptive immune responses in these infections. Consideration of the genetic identity of both the Dengue and Zika flaviviruses as well as the cross-reactivity of relevant T cells along with the actions of CD4+ cytotoxic cells in these infections are also presented. Finally, a summary of the immune biomarkers that have been reported for dengue and Zika viral infections are discussed which may be useful indicators for future anti-viral targets or predictors for disease severity. Together, this information appraises the current understanding of both Zika and Dengue infections, providing insights for future vaccine design approaches against both viruses.
Jamestown Canyon virus (JCV) is a deadly viral infection transmitted by various mosquito species. This mosquito-borne virus belongs to Bunyaviridae family, posing a high public health threat in the in tropical regions of the United States causing encephalitis in humans. Common symptoms of JCV include fever, headache, stiff neck, photophobia, nausea, vomiting, and seizures. Despite the availability of resources, there is currently no vaccine or drug available to combat JCV. The purpose of this study was to develop an epitope-based vaccine using immunoinformatics approaches. The vaccine aimed to be secure, efficient, bio-compatible, and capable of stimulating both innate and adaptive immune responses. In this study, the protein sequence of JCV was obtained from the NCBI database. Various bioinformatics methods, including toxicity evaluation, antigenicity testing, conservancy analysis, and allergenicity assessment were utilized to identify the most promising epitopes. Suitable linkers and adjuvant sequences were used in the design of vaccine construct. 50s ribosomal protein sequence was used as an adjuvant at the N-terminus of the construct. A total of 5 CTL, 5 HTL, and 5 linear B cell epitopes were selected based on non-allergenicity, immunological potential, and antigenicity scores to design a highly immunogenic multi-peptide vaccine construct. Strong interactions between the proposed vaccine and human immune receptors, i.e., TLR-2 and TLR-4, were revealed in a docking study using ClusPro software, suggesting their possible relevance in the immunological response to the vaccine. Immunological and physicochemical properties assessment ensured that the proposed vaccine demonstrated high immunogenicity, solubility and thermostability. Molecular dynamics simulations confirmed the strong binding affinities, as well as dynamic and structural stability of the proposed vaccine. Immune simulation suggest that the vaccine has the potential to effectively stimulate cellular and humoral immune responses to combat JCV infection. Experimental and clinical assays are required to validate the results of this study.
Human respiratory syncytial virus is the most common cause of bronchiolitis and other respiratory infections in infants and the elderly worldwide. We have developed two new oral vaccines using Salmonella typhi TY21a to carry and express the immunogenic epitopes of RSV fusion (F) and attachment (G) glycoproteins on its surface, separately. To evaluate the efficacy of the designed vaccines, BALB/c mice were orally immunized and then infected with RSV. Immune response analyses showed that cellmediated, mucosal and humoral immunity in the vaccinated mice were significantly enhanced compared to the control group. Both vaccines generated a balanced Th1/Th2 immune response which is crucial for efficiency of vaccines against RSV. Furthermore, histopathological examination proved that these vaccines were safe as they did not cause any Th2-associated adverse effects in the lungs of RSV-infected mice. The findings of this research suggest that Salmonella-F and Salmonella-G vaccine candidates may have strong potential to prevent RSV infection.
Marek's disease virus (MDV) is a herpesvirus that induces lymphoma and a variety of non-neoplastic syndromes in chickens. Furthermore, very virulent plus (vv+) MDVs induce a form of immunosuppression (late-MDV-IS) that might involve both neoplastic and non-neoplastic mechanisms. The objective of this study was to evaluate whether the attenuation of MDV-induced tumours and late-MDV-IS occurs simultaneously or can be dissociated. The immunosuppressive ability of three viruses derived from vv+ MDV strain 686 (wild-type 686, the somewhat attenuated molecular clone 686-BAC, and the nononcogenic molecular clone lacking the two copies of the oncogene meq 686-BACΔMEQ) was evaluated. Late-MDV-IS was evaluated indirectly by assessing the negative effect of MDV strains on the protection conferred by infectious laryngotracheitis (ILT) vaccines. Our results showed that the ability to induce late-MDV-IS was attenuated before the ability to induce tumours. Strain 686 induced both tumours and late-MDV-IS, 686-BAC induced tumours but did not induce late-MDV-IS and 686-BACΔMEQ did not induce either tumours or late-MDV-IS. Further comparison of strains 686 and 686-BAC revealed that strain 686 reduced the humoral immune responses to ILTV (1132 vs 2167) more severely, showed higher levels of meq transcripts (2.1E+09 vs 4.98E+8) and higher expression of MDV microRNAs (mdv1-miR-M4-5p and mdv1-miR-M2-3p) in the spleen, and further reduced the percentage of CD45+-MHC-I+splenocytes (13 vs32 %) compared to molecular clone 686-BAC. This study suggests that the immunosuppressive ability of MDV might follow a continuous spectrum and only the most virulent MDVs can overcome a certain threshold level and induce clinical MDV-IS in the ILT model.
The humoral immune responses against 46 different staphylococcal antigens in 27 bacteremia patients infected by clonally related methicillin-resistant Staphylococcus aureus (MRSA) strains of a single sequence type (ST) 239 were investigated. A group of non-infected patients (n = 31) hospitalized for different reasons served as controls. All strains were confirmed as ST 239 by S. aureus and mecA-specific PCR, spa, and multi-locus sequence typing (MLST). In each bacteremia patient, a unique pattern of S. aureus antigen-specific immune responses after infection was observed. Antibody levels among bacteremia patients were significantly higher than controls for HlgB (P = 0.001), LukD (P = 0.009), LukF (P = 0.0001), SEA (P = 0.0001), SEB (P = 0.011), SEC (P = 0.010), SEQ (P = 0.049), IsaA (P = 0.043), IsdA (P = 0.038), IsdH (P = 0.01), SdrD (P = 0.001), SdrE (P = 0.046), EsxA (P = 0.0001), and SA0104 (P = 0.0001). On the other hand, the antibody levels were significantly higher among controls for SSL3 (P = 0.009), SSL9 (P = 0.002), and SSL10 (P = 0.007) when the IgG level on the day of infection was compared with that measured on the day of admission. Diversity was observed in the immune response against the antigens. However, a set of antigens (IsaA, IsdA, IsdH, SdrD, and HlgB) triggered a similar type of immune response in different individuals. We suggest that these antigens could be considered when developing a multi-component (passive) vaccine. SEA and/or its specific antibodies seem to play a critical role during ST239 MRSA bacteremia and SEA-targeted therapy may be a strategy to be considered.
Dengue disease is a major public health problem across the Asia-Pacific region for which there is no licensed vaccine or treatment. We evaluated the safety and immunogenicity of Phase III lots of a candidate vaccine (CYD-TDV) in children in Malaysia.
Objective: To present the frequency and spectrum of viral infections in primary immunodeficient children. Methods: The data was obtained from the Kuwait National Primary Immunodeficiency Disorders (PIDs) Registry during the period of 2004-2018. Results: A total of 274 PID children were registered in KNPIDR during the study period with predominance of immunodeficiencies affecting cellular and humoral immunity, followed by combined immunodeficiencies with associated syndromic features and diseases of immune dysregulation. Overall infectious complications affected 82.4% of the patients, and viral infections affected 31.7% of the registered patients. Forty-five patients (16.4%) developed viral infections caused by at least 2 organisms, among those 20 patients were affected by three or more viral infections. There was a statistically significant association between viral infections and PID category. However, there was no statistically significant association between viral infections and gender or the patients' onset age. There was a total of 170 viral infections during the study period and the causes of these infections were predominated by CMV (22.2%), adenovirus (11.7%), EBV (11.1%), and enteroviruses (7.4%). CMV and parainfluenza infections were more common in the group of immunodeficiencies affecting cellular and humoral immunity while EBV and human papilloma virus (HPV) were more common in the immune dysregulation group and combined immunodeficiencies with associated syndromic features, respectively. The most common presentation was viremia (28.8%) followed by pneumonia (28.2%) and skin infections (17.6%). The most common causes of viremia were CMV followed by adenovirus and EBV, while the most common organisms causing pneumonia were CMV followed by rhinovirus and parainfluenza. There were 80 deaths among the registered patients, 10% were caused by viral infections. Conclusions: Viral infections are common in PIDs and result into a wide-range of clinical manifestations causing significant morbidity and mortality.
Tuberculosis (TB) is one of the deadliest human diseases worldwide caused by mycobacterial infection in the lung. Bacillus Calmette-Guerin (BCG) vaccine protects against disseminated TB in children, but its effectiveness is still questionable due to highly variable protections in adolescence and elderly individuals. Targeting the latency M.tb antigen is a recent therapeutic approach to eradicate dormant pathogen that could possibly lead to disease activation. In this study, we aimed to potentiate immune responses elicited against 16 kDa α-crystalline (HspX) tuberculosis latency antigen by incorporation of Combined Adjuvant for Synergistic Activation of Cellular immunity (CASAC). Histidine-tagged recombinant HspX protein was initially produced in Escherichia coli and purified using Ni-NTA chromatography. To evaluate its adjuvanticity, C57BL/6 mice (n = 5) were initially primed and intradermally immunised in 2-weeks interval for 4 rounds with recombinant HspX, formulated with and without CASAC. Humoral and cell-mediated immune responses elicited against HspX antigen were evaluated using ELISA and Flow Cytometry. Our findings showed that CASAC improved humoral immunity with increased antigen-specific IgG1 and IgG2a antibody response. Stronger CD8+ and Th1-driven immunity was induced by CASAC formulation as supported by elevated level of IFN-γ, TNF-α, IL-12 and IL-17A; and with low IL-10 secretion. Interestingly, adjuvanted HspX vaccine triggered a higher percentage of effector memory T-cell population than those immunised with unadjuvanted vaccine. In conclusion, CASAC adjuvant has great potential to enhance immunogenicity elicited against HspX antigen, which could be an alternative regimen to improve the efficacy of future therapeutic vaccine against Mycobacterium tuberculosis.
Plasmodium vivax is the most widespread and difficult to treat cause of human malaria. The development of vaccines against the blood stages of P. vivax remains a key objective for the control and elimination of vivax malaria. Erythrocyte binding-like (EBL) protein family members such as Duffy binding protein (PvDBP) are of critical importance to erythrocyte invasion and have been the major target for vivax malaria vaccine development. In this study, we focus on another member of EBL protein family, P. vivax erythrocyte binding protein (PvEBP). PvEBP was first identified in Cambodian (C127) field isolates and has subsequently been showed its preferences for binding reticulocytes which is directly inhibited by antibodies. We analysed PvEBP sequence from 316 vivax clinical isolates from eight countries including China (n = 4), Ethiopia (n = 24), Malaysia (n = 53), Myanmar (n = 10), Papua New Guinea (n = 16), Republic of Korea (n = 10), Thailand (n = 174), and Vietnam (n = 25). PvEBP gene exhibited four different phenotypic clusters based on the insertion/deletion (indels) variation. PvEBP-RII (179-479 aa.) showed highest polymorphism similar to other EBL family proteins in various Plasmodium species. Whereas even though PvEBP-RIII-V (480-690 aa.) was the most conserved domain, that showed strong neutral selection pressure for gene purifying with significant population expansion. Antigenicity of both of PvEBP-RII (16.1%) and PvEBP-RIII-V (21.5%) domains were comparatively lower than other P. vivax antigen which expected antigens associated with merozoite invasion. Total IgG recognition level of PvEBP-RII was stronger than PvEBP-RIII-V domain, whereas total IgG inducing level was stronger in PvEBP-RIII-V domain. These results suggest that PvEBP-RII is mainly recognized by natural IgG for innate protection, whereas PvEBP-RIII-V stimulates IgG production activity by B-cell for acquired immunity. Overall, the low antigenicity of both regions in patients with vivax malaria likely reflects genetic polymorphism for strong positive selection in PvEBP-RII and purifying selection in PvEBP-RIII-V domain. These observations pose challenging questions to the selection of EBP and point out the importance of immune pressure and polymorphism required for inclusion of PvEBP as a vaccine candidate.
We had examined the immunogenicity of a series of plasmid DNAs which include neuraminidase (NA) and nucleoprotein (NP) genes from avian influenza virus (AIV). The interleukin-15 (IL-15) and interleukin-18 (IL-18) as genetic adjuvants were used for immunization in combination with the N1 and NP AIV genes. In the first trial, 8 groups of chickens were established with 10 specific-pathogen-free (SPF) chickens per group while, in the second trial 7 SPF chickens per group were used. The overall N1 enzyme-linked immunosorbent assay (ELISA) titer in chickens immunized with the pDis/N1+pDis/IL-15 was higher compared to the chickens immunized with the pDis/N1 and this suggesting that chicken IL-15 could play a role in enhancing the humoral immune response. Besides that, the chickens that were immunized at 14-day-old (Trial 2) showed a higher N1 antibody titer compared to the chickens that were immunized at 1-day-old (Trial 1). Despite the delayed in NP antibody responses, the chickens co-administrated with IL-15 were able to induce earlier and higher antibody response compared to the pDis/NP and pDis/NP+pDis/IL-18 inoculated groups. The pDis/N1+pDis/IL-15 inoculated chickens also induced higher CD8+ T cells increase than the pDis/N1 group in both trials (P<0.05). The flow cytometry results from both trials demonstrated that the pDis/N1+pDis/IL-18 groups were able to induce CD4+ T cells higher than the pDis/N1 group (P<0.05). Meanwhile, pDis/N1+pDis/IL-18 group was able to induce CD8+ T cells higher than the pDis/N1 group (P<0.05) in Trial 2 only. In the present study, pDis/NP was not significant (P>0.05) in inducing CD4+ and CD8+ T cells when co-administered with the pDis/IL-18 in both trials in comparison to the pDis/NP. Our data suggest that the pDis/N1+pDis/IL-15 combination has the potential to be used as a DNA vaccine against AIV in chickens.
Dengue virus (DENV) is considered to be the most important arthropod-borne viral disease and causes more than 100 million human infections annually. To further characterize primary DENV infection in vivo, rhesus macaques were infected with DENV-1, DENV-2, DENV-3, or DENV-4 and clinical parameters, as well as specificity and longevity of serologic responses, were assessed. Overt clinical symptoms were not present after infection. However, abnormalities in blood biochemical parameters consistent with heart, kidney, and liver damage were observed, and changes in plasma fibrinogen, D-dimers, and protein C indicated systemic activation of the blood coagulation pathway. Significant homotypic and heterotypic serum immunoglobulins were present in all animals, and IgG persisted for at least 390 days. Serum neutralizing antibody responses were highly serotype specific by day 120. However, some heterotypic neutralizing activity was noted in infected animals. Identification of serotype-specific host responses may help elucidate mechanisms that mediate severe DENV disease after reinfection.
The Plasmodium falciparum serine repeat antigen (SERA) is one of the promising blood-stage malarial vaccine candidates. In this study, recombinant Mycobacterium bovis bacille Calmette-Guerin (rBCG) expressing the 22 kDa protein (SE22) from the 47 kDa Nterminal domain of serine repeat antigen (SERA), generated in favour of mycobacterium codon usage, elicited specific immune response in BALB/c mice with a mixed Th1/Th2 profile. Immunized sera containing high levels of specific IgG1 and IgG2a against the epitope (as determined by ELISA) were reactive with fixed P. falciparum merozoites as demonstrated by indirect immunofluorescence assay (IFA). Furthermore, the lymphocyte proliferative response to SE22 antigen from rBCG-immunized mice was higher than that of controls. The expression of intracellular cytokines (IL-2, IL-4 and IFNγ) in CD4+- and CD8+-cells was also enhanced following in-vitro stimulation with SE22. These findings indicate that a rBCG-based vaccine candidate expressing a blood-stage antigen of P. falciparum could enhance both humoral and cellular immune responses, thus paving the way for the rational use of rBCG as a vaccine candidate against malaria.
Nipah virus (NiV) is a re-emerging zoonotic pathogen that causes high mortality in humans and pigs. Oral immunization in free-roaming animals is one of the most practical approaches to prevent NiV pandemics. We previously generated a recombinant rabies viruses (RABV) Evelyn-Rokitnicki-Abelseth (ERA) strain, rERAG333E, which contains a mutation from arginine to glutamic acid at residue 333 of glycoprotein (G333E) and serves as an oral vaccine for dog rabies. In this study, we generated two recombinant RABVs, rERAG333E/NiVG and rERAG333E/NiVF, expressing the NiV Malaysian strain attachment glycoprotein (NiV-G) or fusion glycoprotein (NiV-F) gene based on the rERAG333E vector platform. Both rERAG333E/NiVG and rERAG333E/NiVF displayed growth properties similar to those of rERAG333E and caused marked syncytia formation after co-infection in BSR cell culture. Adult and suckling mice intracerebrally inoculated with the recombinant RABVs showed NiV-G and NiV-F expression did not increase the virulence of rERAG333E. Oral vaccination with rERAG333E/NiVG either singularly or combined with rERAG333E/NiVF induced significant NiV neutralizing antibody against NiV and RABV, and IgG to NiV-G or NiV-F in mice and pigs. rERAG333E/NiVG and rERAG333E/NiVF thus appeared to be suitable candidates for further oral vaccines for potential animal targets in endemic areas of NiV disease and rabies.
Besides causing mild hand, foot and mouth infections, Enterovirus A71 (EV-A71) is associated with neurological complications and fatality. With concerns about rising EV-A71 virulence, there is an urgency for more effective vaccines. The live attenuated vaccine (LAV) is a more valuable vaccine as it can elicit both humoral and cellular immune responses. A miRNA-based vaccine strain (pIY) carrying let-7a and miR-124a target genes in the EV-A71 genome which has a partial deletion in the 5'NTR (∆11 bp) and G64R mutation (3Dp°l) was designed. The viral RNA copy number and viral titers of the pIY strain were significantly lower in SHSY-5Y cells that expressed both let-7a and miR-124a. Inhibition of the cognate miRNAs expressed in RD and SHSY-5Y cells demonstrated de-repression of viral mRNA translation. A previously constructed multiply mutated strain, MMS and the pIY vaccine strain were assessed in their ability to protect 4-week old mice from hind limb paralysis. The MMS showed higher amounts of IFN-γ ex vivo than the pIY vaccine strain. There was absence of EV-A71 antigen in the skeletal muscles and spinal cord micrographs of mice vaccinated with the MMS and pIY strains. The MMS and pIY strains are promising LAV candidates developed against severe EV-A71 infections.