Detection and Molecular Characterization of Porcine Parvovirus 7 in Eastern Inner Mongolia Autonomous Region, China

First Molecular Characterisation of Porcine Parvovirus 7 (PPV7) in Italy

Porcine parvoviruses (PPVs) are among the most important agents of reproductive failure in swine worldwide. PPVs comprise eight genetically different species ascribed to four genera: Protoparvovirus (PPV1, PPV8), Tetraparvovirus (PPV2-3), Copiparvovirus (PPV4-6), and Chaphamaparvovirus (PPV7). In 2016, PPV7 was firstly detected in the USA and afterwards in Europe, Asia, and South America. Recently, it was also identified in Italy in pig farms with reproductive failure. This study aimed to evaluate the circulation of PPV7 in domestic and wild pigs in Sardinia, Italy. In addition, its coinfection with Porcine Circovirus 2 (PCV2) and 3 (PCV3) was analysed, and PPV7 Italian strains were molecularly characterised. PPV7 was detected in domestic pigs and, for the first time, wild pigs in Italy. The PPV7 viral genome was detected in 20.59% of domestic and wild pig samples. PPV7 detection was significantly lower in domestic pigs, with higher PCV2/PCV3 co-infection rates observed in PPV7-positive than in PPV7-negative domestic pigs. Molecular characterisation of the NS1 gene showed a very high frequency of recombination that could presumably promote virus spreading.

Molecular Survey on Porcine Parvoviruses (PPV1-7) and Their Association with Major Pathogens in Reproductive Failure Outbreaks in Northern Italy

Successful reproductive performance is key to farm competitiveness in the global marketplace. Porcine parvovirus 1 (PPV1) has been identified as a major cause of reproductive failure, and since 2001 new species of porcine parvoviruses, namely PPV2-7, have been identified, although their role is not yet fully understood yet. The present study aimed to investigate PPVs' presence in reproductive failure outbreaks occurring in 124 farms of northern Italy. Fetuses were collected from 338 sows between 2019 and 2021 and tested for PPVs by real-time PCR-based assays and for other viruses responsible for reproductive disease. At least one PPV species was detected in 59.7% (74/124) of the tested farms. In order, PPV1, PPV5, PPV6, PPV7 and PPV4 were the most frequently detected species, whereas fewer detections were registered for PPV2 and PPV3. Overall, the new PPV2-7 species were detected in 26.6% (90/338) of the cases, both alone or in co-infections: PCV-2 (7.1%, 24/338), PCV-3 (8.2%, 28/338), and PRRSV-1 (6.2%, 21/338) were frequently identified in association with PPVs. Single PPVs detections or co-infections with other agents commonly responsible for reproductive failure should encourage future studies investigating their biological, clinical, and epidemiological role, for a better preparedness for potential emerging challenges in intensive pig production.

A Subunit Vaccine Based on the VP2 Protein of Porcine Parvovirus 1 Induces a Strong Protective Effect in Pregnant Gilts

Porcine parvovirus 1 (PPV1) is one of the most prevalent pathogens that can cause reproductive disorder in sows. The VP2 protein of PPV1 is the most important immunogenic protein that induces neutralizing antibodies and protective immunity. Thus, VP2 is considered an ideal target antigen for the development of a genetically engineered PPV1 vaccine. In this study, the baculovirus transfer vector carrying the HR5-P10-VP2 expression cassette was successfully constructed with the aim of increasing the expression levels of the VP2 protein. The VP2 protein was confirmed using SDS‒PAGE and Western blot analyses. Electronic microscope analysis showed that the recombinant VP2 proteins were capable of self-assembling into VLPs with a diameter of approximately 25 nm. The immunogenicity of the VP2 subunit vaccine was evaluated in pigs. The results showed that VP2 protein emulsified with ISA 201VG adjuvant induced higher levels of HI antibodies and neutralizing antibodies than VP2 protein emulsified with IMS 1313VG adjuvant. Furthermore, the gilts immunized with the ISA 201VG 20 μg subunit vaccine acquired complete protection against PPV1 HN2019 infection. In contrast, the commercial inactivated vaccine provided incomplete protection in gilts. Therefore, the VP2 subunit vaccine is a promising genetically engineered vaccine for the prevention and control of PPV1.

The Synergic Role of Emerging and Endemic Swine Virus in the Porcine Respiratory Disease Complex: Pathological and Biomolecular Analysis

Porcine respiratory disease complex (PRDC) represents a significant threat to the swine industry, causing economic losses in pigs worldwide. Recently, beyond the endemic viruses PRRSV and PCV2, emerging viruses such as TTSuV, PCV3, and PPV2, have been associated with PRDC, but their role remains unclear. This study investigates the presence of PCV2 and PRRSV and emerging viruses (PCV3, TTSuV, and PPV2) in the lungs of swine belonging to different age groups by histopathology and real-time PCR. The prevalent lung lesion was interstitial pneumonia with increased severity in post-weaning pigs. PRRSV was detected in 33% of piglets' lungs and in 20% of adults and post-weaning pigs with high Ct, while PCV2 was found in 100% of adult pigs, 33% of post-weaning pigs, and 22% of piglets, with low Ct in post-weaning pigs. PCV3 was present in all categories and coexisted with other viruses. TTSuV was detected in all swine in combination with other viruses, possibly influencing the disease dynamics, while PPV2 was detected in 100% of adults' and 90% of piglets' lungs. The detection of TTSuV, PCV3, and PPV2 in affected pigs prioritizes the need for comprehensive approaches in implementing appropriate control measures and minimizing economic losses associated with PRDC.