A modified-live porcine reproductive and respiratory syndrome virus (PRRSV)-1 vaccine protects late-term pregnancy gilts against heterologous PRRSV-1 but not PRRSV-2 challenge

Jeong, Jiwoon; Kang, Il Jun; Kim, S.; Park, Seong‐Jik; Park, K. H.; Oh, Tae-Kwang; Yang, Siyeon; Chae, C.

doi:10.1111/tbed.12862

Cited by 14 publications

(20 citation statements)

References 18 publications

(33 reference statements)

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“…The protective role of NA is, however, limited in PRRSV vaccination [27]. Despite the low levels of NA elicited in response to PRRSV vaccination, vaccinated sows are still able to efficiently clear PRRSV viremia [94][95][96][97][98][99][100][101][102]. It is presumed that this was at least partially dependent on cell-mediated immunity, especially the host IFN-γ response, as IFN-γ is known to inhibit PRRSV replication [28,29].…”

Section: Criteria Of Vaccine Efficacy For Maternal Reproductive Failurementioning

confidence: 99%

Commercial PRRS Modified-Live Virus Vaccines

Chae

2021

Vaccines

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Porcine reproductive and respiratory syndrome (PRRS) virus (PRRSV) presents one of the challenging viral pathogens in the global pork industry. PRRS is characterized by two distinct clinical presentations; reproductive failure in breeding animals (gilts, sows, and boars), and respiratory disease in growing pigs. PRRSV is further divided into two species: PRRSV-1 (formerly known as the European genotype 1) and PRRSV-2 (formerly known as the North American genotype 2). A PRRSV-2 modified-live virus (MLV) vaccine was first introduced in North America in 1994, and, six years later, a PRRSV-1 MLV vaccine was also introduced in Europe. Since then, MLV vaccination is the principal strategy used to control PRRSV infection. Despite the fact that MLV vaccines have shown some efficacy, they were problematic as the efficacy of vaccine was often unpredictable and depended highly on the field virus. This paper focused on the efficacy of commercially available MLV vaccines at a global level based on respiratory disease in growing pigs, and maternal and paternal reproductive failure in breeding animals.

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Section: Criteria Of Vaccine Efficacy For Maternal Reproductive Failurementioning

confidence: 99%

Commercial PRRS Modified-Live Virus Vaccines

Chae

2021

Vaccines

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“…PRRSV-2 isolate, and cross-protection between PRRSV-1 and PRRSV-2 is considered insignificant, as demonstrated in different studies carried out in adult sows (38,39), boars (40,41), and piglets (42,43). This is probably due to the enormous genetic divergence between the two PRRSV species (14).…”

Section: Discussionmentioning

confidence: 99%

“…However, it should be mentioned that the characteristics of the PRRSV isolates used for the secondary exposure in some of those groups might have also contributed to the outcome of infection. Thus, the pigs of group A.2 were exposed to a PRRSV-2 isolate, and cross-protection between PRRSV-1 and PRRSV-2 is considered insignificant, as demonstrated in different studies carried out in adult sows ( 38 , 39 ), boars ( 40 , 41 ), and piglets ( 42 , 43 ). This is probably due to the enormous genetic divergence between the two PRRSV species ( 14 ).…”

Section: Discussionmentioning

confidence: 99%

The Ability of Porcine Reproductive and Respiratory Syndrome Virus Isolates to Induce Broadly Reactive Neutralizing Antibodies Correlates With In Vivo Protection

et al. 2021

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Porcine reproductive and respiratory syndrome (PRRS) is considered one of the most relevant diseases of swine. The condition is caused by PRRS virus (PRRSV), an extremely variable virus of the Arteriviridae family. Its heterogeneity can be responsible, at least partially, of the poor cross-protection observed between PRRSV isolates. Neutralizing antibodies (NAs), known to play a role in protection, usually poorly recognize heterologous PRRSV isolates, indicating that most NAs are strain-specific. However, some pigs develop broadly reactive NAs able to recognize a wide range of heterologous isolates. The aim of this study was to determine whether PRRSV isolates that induce broadly reactive NAs as determined in vitro are able to confer a better protection in vivo. For this purpose two in vivo experiments were performed. Initially, 40 pigs were immunized with a PRRSV-1 isolate known to induce broadly reactive NAs and 24 additional pigs were used as controls. On day 70 after immunization, the pigs were divided into eight groups composed by five immunized and three control pigs and exposed to one of the eight different heterologous PRRSV isolates used for the challenge. In the second experiment, the same experimental design was followed but the pigs were immunized with a PRRSV-1 isolate, which is known to generate mostly strain-specific NAs. Virological parameters, specifically viremia and the presence of challenge virus in tonsils, were used to determine protection. In the first experiment, sterilizing immunity was obtained in three groups, prevention of viremia was observed in two additional groups, although the challenge virus was detected occasionally in the tonsils of immunized pigs, and partial protection, understood as a reduction in the frequency of viremia compared with controls, was recorded in the remaining three groups. On the contrary, only partial protection was observed in all groups in the second experiment. The results obtained in this study confirm that PRRSV-1 isolates differ in their ability to induce cross-reactive NAs and, although other components of the immune response might have contributed to protection, pigs with cross-reactive NAs at the time of challenge exhibited better protection, indicating that broadly reactive NAs might play a role in protection against heterologous reinfections.

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“…At the individual level, the efficacy of PRRS MLV is generally described as protective against both reproductive failure and respiratory disorders, providing multiple benefits including but not limited to the reduction of clinical signs, lessened macroscopic and microscopic lung lesion and viremia, shortened viral shedding period and reduced secondary bacterial infection [30,[92][93][94]. Reports in a gilts vaccination and late pregnant term challenge study have shown that MLV vaccination can improve the reproductive performance in sows and piglet health and overall viability, compared with unvaccinated sows [95][96][97].…”

Section: Homologous Protectionmentioning

confidence: 99%

Porcine Reproductive and Respiratory Syndrome Modified Live Virus Vaccine: A “Leaky” Vaccine with Debatable Efficacy and Safety

Zhou

Yang

2021

Vaccines

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Porcine reproductive and respiratory syndrome (PRRS) caused by the PRRS virus (PRRSV) is one of the most economically important diseases, that has significantly impacted the global pork industry for over three decades, since it was first recognized in the United States in the late 1980s. Attributed to the PRRSV extensive genetic and antigenic variation and rapid mutability and evolution, nearly worldwide epidemics have been sustained by a set of emerging and re-emerging virus strains. Since the first modified live virus (MLV) vaccine was commercially available, it has been widely used for more than 20 years, for preventing and controlling PRRS. On the one hand, MLV can induce a protective immune response against homologous viruses by lightening the clinical signs of pigs and reducing the virus transmission in the affected herd, as well as helping to cost-effectively increase the production performance on pig farms affected by heterologous viruses. On the other hand, MLV can still replicate in the host, inducing viremia and virus shedding, and it fails to confer sterilizing immunity against PRRSV infection, that may accelerate viral mutation or recombination to adapt the host and to escape from the immune response, raising the risk of reversion to virulence. The unsatisfied heterologous cross-protection and safety issue of MLV are two debatable characterizations, which raise the concerns that whether it is necessary or valuable to use this leaky vaccine to protect the field viruses with a high probability of being heterologous. To provide better insights into the immune protection and safety related to MLV, recent advances and opinions on PRRSV attenuation, protection efficacy, immunosuppression, recombination, and reversion to virulence are reviewed here, hoping to give a more comprehensive recognition on MLV and to motivate scientific inspiration on novel strategies and approaches of developing the next generation of PRRS vaccine.

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A modified-live porcine reproductive and respiratory syndrome virus (PRRSV)-1 vaccine protects late-term pregnancy gilts against heterologous PRRSV-1 but not PRRSV-2 challenge

Cited by 14 publications

References 18 publications

Commercial PRRS Modified-Live Virus Vaccines

Commercial PRRS Modified-Live Virus Vaccines

The Ability of Porcine Reproductive and Respiratory Syndrome Virus Isolates to Induce Broadly Reactive Neutralizing Antibodies Correlates With In Vivo Protection

Porcine Reproductive and Respiratory Syndrome Modified Live Virus Vaccine: A “Leaky” Vaccine with Debatable Efficacy and Safety

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