Characterization of the Immune Response of MERS-CoV Vaccine Candidates Derived from Two Different Vectors in Mice

Abstract

Middle East respiratory syndrome (MERS) is an acute, high-mortality-rate, severe infectious disease caused by an emerging MERS coronavirus (MERS-CoV) that causes severe respiratory diseases. The continuous spread and great pandemic potential of MERS-CoV make it necessarily important to develop effective vaccines. We previously demonstrated that the application of Gram-positive enhancer matrix (GEM) particles as a bacterial vector displaying the MERS-CoV receptor-binding domain (RBD) is a very promising MERS vaccine candidate that is capable of producing potential neutralization antibodies. We have also used the rabies virus (RV) as a viral vector to design a recombinant vaccine by expressing the MERS-CoV S1 (spike) protein on the surface of the RV. In this study, we compared the immunological efficacy of the vaccine candidates in BALB/c mice in terms of the levels of humoral and cellular immune responses. The results show that the rabies virus vector-based vaccine can induce remarkably earlier antibody response and higher levels of cellular immunity than the GEM particles vector. However, the GEM particles vector-based vaccine candidate can induce remarkably higher antibody response, even at a very low dose of 1 µg. These results indicate that vaccines constructed using different vaccine vector platforms for the same pathogen have different rates and trends in humoral and cellular immune responses in the same animal model. This discovery not only provides more alternative vaccine development platforms for MERS-CoV vaccine development, but also provides a theoretical basis for our future selection of vaccine vector platforms for other specific pathogens.

Coronavirus Disease 2019–COVID-19

“…The majority of the treatment options and strategies that are being evaluated for SARS-CoV-2 (COVID-19) have been taken from our previous experiences in treating SARS-CoV, MERS-CoV, and other emerging viral diseases. Several therapeutic and preventive strategies, including vaccines, immunotherapeutics, and antiviral drugs, have been exploited against the previous CoV outbreaks (SARS-CoV and MERS-CoV) ( 8 , 104 , 164 – 167 ). These valuable options have already been evaluated for their potency, efficacy, and safety, along with several other types of current research that will fuel our search for ideal therapeutic agents against COVID-19 ( 7 , 9 , 19 , 21 , 36 ).…”

COVID-19, an emerging coronavirus infection: advances and prospects in designing and developing vaccines, immunotherapeutics, and therapeutics

“…The immune responses to these vaccine candidates were evaluated in BALB/c mice for cellular and humoral immune responses, which showed that RVbased vaccine stimulates significantly higher levels of cellular immunity and earlier antibody responses in comparison to the GEM particle vector. 12 The possibility of developing a universal CoV vaccine was assessed based on the similarity in T-cell epitopes of SARSand MERS-CoV that confirmed the potential for crossreactivity among CoVs. 25 SARS-CoV-2 shares high genetic similarity with the SARS-CoV 26 such that vaccines developed for SARS-CoV may exhibit cross-reactivity to SARS-CoV-2.…”

“…5 Various vaccines, immunotherapeutics, and drug options have been explored during the recent threats of Zika, Ebola, and Nipah viruses [6][7][8] as well as against previous CoVs including SARS-and MERS-CoVs. 3,5,[9][10][11][12] These valuable options can be exploited for their potency, efficacy, and safety along with expediting other ongoing research 2,4,[13][14][15] so as to discover valuable modalities for tackling the emerging COVID-19, but as yet there is no effective vaccine or therapeutic, for which intense efforts are ongoing.…”

Coronavirus Disease 2019 – COVID-19

“…The majority of the therapeutic options and strategies that we are evaluating in SARS-CoV-2 (COVID-19) are taken from our previous experiences in treating SARS-CoV, MERS-CoV, and other emerging viral diseases. Several therapeutic and preventive strategies, including vaccines, immunotherapeutics, and antiviral drugs, have been explored against the previous coronavirus outbreaks caused by SARS-CoV and MERS-CoV (8,104,(164)(165)(166)(167). These valuable options have already been evaluated for their potency, efficacy, and safety along with several other ongoing types of research will fuel our search for ideal therapeutic agent against COVID-19 (7,9,19,21,36).…”

“…The RV vector-based vaccines against MERS-CoV can induce faster antibody response as well as higher degrees of cellular immunity compared to the Gram-positive enhancer matrix (GEM) particles vector-based vaccine. However, the latter can induce a very higher antibody response at lower doses (167). Hence, the degree of humoral and cellular immune response produced by such vaccines depends upon the vector used.…”