Outbreaks of zoonotic viral diseases pose a severe threat to public health and economies worldwide, with this currently being more prominent than it previously was human history. These emergency zoonotic diseases that originated and transmitted from vertebrates to humans have been estimated to account for approximately one billion cases of illness and have caused millions of deaths worldwide annually. The recent emergence of severe acute respiratory syndrome coronavirus-2 (coronavirus disease 2019) is an excellent example of the unpredictable public health threat causing a pandemic. The present review summarizes the literature data regarding the main vaccine developments in human clinical phase I, II and III trials against the zoonotic positive-sense single-stranded RNA viruses belonging to the Coronavirus and Alphavirus genera, including severe acute respiratory syndrome, Middle east respiratory syndrome, Venezuelan equine encephalitis virus, Semliki Forest virus, Ross River virus, Chikungunya virus and O'nyong-nyong virus. That there are neither vaccines nor effective antiviral drugs available against most of these viruses is undeniable. Therefore, new explosive outbreaks of these zoonotic viruses may surely be expected. The present comprehensive review provides an update on the status of vaccine development in different clinical trials against these viruses, as well as an overview of the present results of these trials. Contents1. Introduction 2. Middle East respiratory syndrome coronavirus 3. Severe acute respiratory syndrome coronavirus 4. Chikungunya and O'nyong-nyong virus 5. Venezuelan equine encephalitis virus 6. Ross River virus 7. Semliki Forest virus 8. Conclusions and future perspectives

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Newcastle disease virus (NDV) is considered one of the most devastating avian viral pathogenic agents, causing a tremendous economic burden to the poultry industry worldwide. The current study was conducted to gain deep insights into the molecular and phylogenetic analyses of the complete hemagglutinin-neuraminidase (HN) coding region among NDV isolates. The collected samples, obtained from different parts of Iran from July 2017 to February 2020, were used for phylogenic analysis during this study. The results confirmed the VII.1.1, which was previously known as subgenotype VIIL, as the predominant subgenotype circulating in commercial broiler farms of Iran. Identification of (a) an additional N-glycosylation site at position 144 (NIS); (b) mutations S315P and I369V related to increasing the viral thermostability; (C) cysteine residues at positions 123; (d) amino acid substitutions in the HN antigenic sites, especially the mutations I514V and E347Q, as well as the other mutant within HN binding sites of the VII.1.1 subgenotype, seems to suggest the idea that this new subgenotype of NDV may possess a high level of pathogenicity and virulence among other NDV subgenotypes. Furthermore, the annual rate of change based on the HN gene of Iranian NDV was calculated at about 1.8088E-3 from 2011 to 2020. In conclusion, the results demonstrate an additional N-glycosylation site at position 144 (NIS), which may alter the virulence of the isolates. Besides, finding the thermostable mutations (S315P and I369V) and the other amino acid substitutions among the VII.1.1 subgenotype isolates may lead to vaccination failure against this new NDV subgenotype.