Evaluation of replicon particle vaccines for porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome (PRRS) is one of the most important diseases of domestic swine. The etiologic agent is a virus (PRRSV), and has proven to be a difficult target for control and eradication efforts. Therefore, it is desirable to develop an improved generation of PRRS vaccines to address these and other shortcomings. Alphavirus-derived replicon particle (RP) vaccines have demonstrated efficacy and safety in a wide range of disease and animal models. Recently, an RP platform derived from Venezuelan equine encephalitis virus (strain, TC-83) was developed for use in veterinary vaccines, including vaccines for swine. The key attributes of this technology are that RPs are propagation-defective, single-cycle RNA virus vectors, and are capable of eliciting potent humoral and cellular immune responses to a wide variety of antigens. In these studies, RP were used to express PRRSV proteins GP3, GP4, GP5, and M as vaccine antigens in young pigs. Vaccinated animals developed specific humoral and cellular immune responses, and also had reduced viremia and viral load post-challenge. Similar vaccine candidates were evaluated in pregnant gilts, but no significant reduction in disease were observed compared to controls. Additionally, an RP influenza vaccine administered 24 hours prior to PRRSV challenge reduced viremia and viral load in young pigs compared to controls. This effect was independent of PRRSV-derived antigens, highlighting the utility of the RP to investigate the host immune response to viral infection. Overall, these data demonstrate that RP represent a powerful tool for future PRRS vaccine research and disease control efforts

Passive Immunization of Piglets Using Equine Plasma Containing PRRS Virus-Neutralizing Antibodies

Horses were inoculated with several strains of virulent PRRS virus. Sera from the horses were tested for the presence of PRRS virus-neutralizing antibodies. Large volumes of equine plasma were collected and used to passively immunize piglets. Sera were collected at various time points after immunization and tested for virus-neutralizing activity. These results show that horses are capable of generating high neutralizing antibody titers to PRRSV when exposed to virulent virus. Piglets develop neutralizing antibody titers to PRRSV when passively immunized with a sufficient volume of ά-PRRSV equine plasma

Expression and Immunogenicity of an Alphavirus Replicon African Swine Fever Virus Vaccine Candidate in Swine

African swine fever virus (ASFV) proteins were expressed in an alphavirus based replicon expression system. Pigs vaccinated with the recombinant vectors developed ASFV-specific antibodies. This is the first known use of this technology against ASFV

Rapid Development of Efficacious Swine Vaccines for Pandemic H1N1

Pandemic H1N1 (pH1N1) influenza was first reported in the United States in April 2009. Since then, the virus has spread worldwide in both human and swine populations. Currently, pH1N1 influenza is the most common H1N1 virus infecting pigs in the United States. Vaccination of swine against pH1N1 represents the single best method of protecting against infection

Preparation of GP5-M Heterodimer Glycantype Specific Recombinant Protein and Replicon Particles

Porcine Reproductive and Respiratory Syndrome (PRRS) imposes a huge financial burden on the swine industry. Thus, there is a clear and immediate need for improved PRRS virus (PRRSV) vaccines. Our group has proposed a new classification scheme for PRRSV strains that allows for immunological differentiation based on level of GP5 glycosylation. This classification based on glycantype has allowed us to choose PRRSV strains that offer the best chance of protection against PRRS

Replicon Particle Porcine Reproductive and Respiratory Syndrome Virus Vaccine Provides Partial Protection from Challenge

Replicon particles (RPs) expressing the GP5 and Matrix structural proteins of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) were created and compared to inactivated PRRSV in a challenge study. Pigs that received the RP vaccine had lower live virus titers and showed lower IDEXX ELISA values following challenge when compared to other groups. These results show that the RP vaccine provided partial protection against challenge with virulent PRRSV. Also, the RP vaccine allows for differentiation between vaccinated and naturally infected animals

Replicon Particle Administration Prior to Challenge Reduces PRRSV Viremia

Vaccination of swine with an alphavirus-derived replicon particle vaccine stimulates a non-specific immune response. This effect was seen when animals were challenged with PRRSV at 24 hours post-vaccination. Animals that received vaccine had reduced viremia as measured by quantitative RT-PCR when compared to placebo. These results highlight the potential of replicon particle vaccines to induce robust immune responses in swine

Development of an Alphavirus Replicon Classical Swine Fever Virus Vaccine Candidate

Classical swine fever virus (CSFV) E2 glycoprotein was expressed in an alphavirus based replicon expression system. Vaccinated pigs developed CSFV-specific antibodies. This is the first known use of this technology against CSFV

Passive Immunization of Piglets with Hyperimmune Plasma Containing Virus Neutralizing Antibodies to Porcine Reproductive and Respiratory Syndrome Virus

Polyvalent hyperimmune plasma (HP) with high-titers of virus neutralizing (VN) antibody to porcine reproductive and respiratory syndrome virus (PRRSV) strains was produced in gilts and used to passively immunize 3 week old piglets. The piglets were subsequently challenged with live virus. Results showed delay of viremia, decrease in live virus titers, decrease in gross lung lesions, or delay in transmission to naïve, non-immunized sentinel pigs

Characterization of Newly Revealed Sequences in the Infectious Myonecrosis Virus Genome in \u3ci\u3eLitopenaeus vannamei\u3c/i\u3e

Infectious myonecrosis virus (IMNV) causes significant economic losses in farmed shrimp, where associated mortality in ponds can reach 70%. To explore host/pathogen interactions, a next-generation sequencing approach using lymphoid organ tissue from IMNV-infected Litopenaeus vannamei shrimp was conducted. Preliminary sequence assembly of just the virus showed that there were at least an additional 639 bp at the 5′ terminus and 23 nt at the 3′ terminus as compared with the original description of the IMNV genome (7561 nt). Northern blot and reverse transcription-PCR analysis confirmed the presence of novel sequence at both ends of the genome. Using 5′ RACE, an additional 4 nt were discovered; 3′ RACE confirmed the presence of 22 bp rather than 23 bp of sequence. Based on these data, the IMNV genome is 8226 bp in length. dsRNA was used to trigger RNA interference (RNAi) and suppress expression of the newly revealed genome sections at the 5′ end of the IMNV genome in IMNV-infected L. vannamei. An RNAi trigger targeting a 376 bp length of the 5′ UTR did not improve survival of infected shrimp. In contrast, an RNAi trigger targeting a 381 bp sequence in ORF1 improved survival to 82.2% as compared with 2.2% survival in positive control animals. These studies revealed the importance of the new genome sections to produce high-titre infection, and associated disease and mortality, in infected shrimp