Abstract
The importance of vaccines can never be underestimated, especially those being developed for new and emerging viruses. The coronavirus disease 2019 (COVID-19) pandemic has changed the world in many ways, but one very sobering realization has been how vulnerable we really are as a species. Scientists have always been cognizant of the fact that a new virus could emerge at any time and represent a global threat, but the emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has painfully illustrated the fact that in some cases, such a virus can be so new to our species that absolutely no one anywhere in the world has immunity against it. Numerous new viruses have emerged for the past 20 years, but none of them caused pandemics. So what actually makes a certain virus a pandemic threat? In the case of the COVID-19 pandemic, it was likely the combination of SARS-CoV-2 being a virus that was completely new to the human immune system, paired with the ability of this virus to spread so well. Other factors undoubtedly contributed as well, but what is clear is that never before has the world been so interested in and focused on the development of vaccines. The COVID-19 vaccines were developed surprisingly fast, and seem to be working in the real world even better than clinical trial data predicted. To set the stage for the coming Special Issues on Coronaviruses, this issue is devoted to highlighting some vaccine research in a number of other important human and animal viruses.
In this issue, two articles address foot and mouth disease viruses (FMDVs). The first article, by Kim et al., analyzed age-stratified serological statuses of Korean children to determine candidate serotypes for hand, foot, and mouth disease (HFMD) vaccine development. Their results indicated that Enterovirus A71 and coxsackievirus A6 were the most suitable serotypes to target, and the authors concluded that their data provide a new perspective for HFMD vaccine development and policy making in Asian countries. In a second article on the topic of foot and mouth disease (FMD), Moghddam et al. focus on differentiating FMDV infected from vaccinated animals. The authors describe an in-house ELISA targeting the FMDV 3AB nonstructural protein that they conclude has higher sensitivity than the 3D-ELISA, and can be used for detection and differentiation of FMD-infected versus vaccinated animals.
Also in this issue, four timely articles deal with improvement of responses to vaccines. One study by Langellotti et al. investigated the immune response elicited in mice by DNA vaccines based on the bovine herpesvirus-1 (BoHV-1) glycoprotein D in the presence or absence of two different adjuvants. Based on their findings, the authors highly recommended the inclusion of these adjuvants in a BoHV-1 DNA vaccine for cattle. In an effort to identify ways to improve immunization with hepatitis B vaccines, Wang et al. focused on the contribution of human beta defensin 2 (hBD2) in the immune response against a hepatitis B vaccine. Based on their findings, the authors concluded that hBD2 improves immature dendritic cell function and the immune efficiency of the vaccine in mice.
In the first of two articles focused on vaccine improvement in the context of avian influenza viruses (AIVs), Alqazlan et al. investigated the potential effects of probiotics on the immunogenicity of a CpG-adjuvanted whole inactivated (WIV) H9N2 vaccine. Upon examination of antibody titers and cell-mediated immunity, the authors concluded that the use of probiotics could enhance the immunogenicity of such vaccines. A second AIV article by Zhao et al. focuses on the highly pathogenic, but poorly immunogenic, H7N9 virus. In a strategy whereby the H7N9 genes were placed in the backbone of an H1N1 (PR8) virus and tested with or without MF59 adjuvant, the authors proposed that based on their findings, a split AIV H7N9 vaccine combined with MF59 might significantly improve immune responses to influenza vaccinations in elderly humans.
Finally, on the topic of challenges in veterinary vaccines, Huić Babić et al. address infectious bursal disease (IBD) of young chickens in an effort to improve on current vaccination strategies. The team performed in vitro characterization, along with efficacy and safety testing of a live intermediate plus vaccine against IBD. In a field trial conducted on commercial boilers, they observed 95% protection against very virulent IBD virus.
In closing, despite the unfortunate and uncertain times we are living in, one of the many silver linings is the heightened global interest and awareness in viral vaccines. In the next few months, we will all find out if the COVID-19 vaccines are as good as their makers claim them to be.