Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV), one of the most economically significant pathogens worldwide, has caused numerous outbreaks during the past 30 years. PRRSV infection causes reproductive failure in sows and respiratory disease in growing and finishing pigs, leading to huge economic losses for the swine industry. This impact has become even more significant with the recent emergence of highly pathogenic PRRSV strains from China, further exacerbating global food security. Since new PRRSV variants are constantly emerging from outbreaks, current strategies for controlling PRRSV have been largely inadequate, even though our understanding of PRRSV virology, evolution and host immune response has been rapidly expanding. Meanwhile, practical experience has revealed numerous safety and efficacy concerns for currently licensed vaccines, such as shedding of modified live virus (MLV), reversion to virulence, recombination between field strains and MLV and failure to elicit protective immunity against heterogeneous virus. Therefore, an effective vaccine against PRRSV infection is urgently needed. Here, we systematically review recent advances in PRRSV vaccine development. Antigenic variations resulting from PRRSV evolution, identification of neutralizing epitopes for heterogeneous isolates, broad neutralizing antibodies against PRRSV, chimeric virus generated by reverse genetics, and novel PRRSV strains with interferon-inducing phenotype will be discussed in detail. Moreover, techniques that could potentially transform current MLV vaccines into a superior vaccine will receive special emphasis, as will new insights for future PRRSV vaccine development. Ultimately, improved PRRSV vaccines may overcome the disadvantages of current vaccines and minimize the PRRS impact to the swine industry.
Highlights
Porcine reproductive and respiratory syndrome virus (PRRSV) is a positive-stranded enveloped RNA virus which belongs to the genus Arterivirus, family Arteriviridae and order Nidovirales (Lunney et al, 2016)
We summarize both the progress and challenges faced by current PRRSV vaccine researchers and provide new insights to guide future efforts
Since antibody-dependent enhancement (ADE) of PRRSV could be mediated by sub-neutralizing antibody as well (Yoon et al, 1996, 1997), NA raised by one strain of modified live virus (MLV) in immunized herds could serve as sub-neutralizing antibody for a circulating or re-emerging heterogeneous virus
Summary
Porcine reproductive and respiratory syndrome virus (PRRSV) is a positive-stranded enveloped RNA virus which belongs to the genus Arterivirus, family Arteriviridae and order Nidovirales (Lunney et al, 2016). Ingelvac PRRS R MLV, has been commercially available and widely used for more than two decades, the prevalence of PRRSV infection in swine herds is still high and vaccination has demonstrated only limited control of PRRS (Butler et al, 2014) This dilemma of PRRSV vaccine development has been somewhat surprising, since a number of vaccines against equine arteritis virus (EAV, another member of the genus Arterivirus) are available and are highly effective (Balasuriya and MacLachlan, 2004). All attendees, including experts in PRRS, virology, immunology and vaccinology, as well as clinical veterinarians, academics and vaccine industry scientists set new standards for the generation of PRRSV vaccines These standards include rapid induction of immunity, protection against most
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