Genomic Stability for PCR Detection of Infectious Laryngotracheitis Virus and Infectious Bronchitis Virus in Poultry Dust Samples Stored Under Different Conditions.

Dust collected from the poultry house has been increasingly used as a population-level sample to monitor the presence of pathogens or to evaluate the administration of live vaccines. However, there are no guidelines for the storage of this sample type. This study investigated the stability of infectious laryngotracheitis virus (ILTV), a DNA virus, and infectious bronchitis virus (IBV), an RNA virus, in poultry dust kept under temperature and moisture conditions that mimic on-farm and laboratory storage. Dust samples were collected from chicks spray vaccinated with a live IBV vaccine and inoculated with a field ILTV strain via eye drop. Samples were stored under different moisture conditions (dry = 2% moisture, moist = 22%-71% moisture) and temperatures (-20, 4, 25, and 37 C) for different durations (0, 7, and 14 days, and 1, 2, 3, and 4 mo) in a factorial arrangement, followed by quantitative PCR for detection of virus genome copies (GC). The length of storage, moisture level, and storage temperature affected the viral genome load for ILTV and IBV but did not affect the number of positive samples for each virus. All treatment combinations were ILTV positive for at least 4 mo. In dry dust samples, all storage temperatures or durations had quantifiable ILTV or IBV GC. Moisture addition had a detrimental effect on viral genome load, causing an overall reduction of 0.3 log 10 for ILTV GC (7.29 and 6.97 log 10, P = 0.0001), and 1.3 log 10 for IBV GC (5.95 and 4.66 log 10, P = 0.0001), which are unlikely to have biologic significance. In conclusion, dry dust can be stored at any temperature up to 37 C for at least 4 mo without loss in qPCR detection of ILTV or IBV GC. Collection or storage of moist dust should be avoided, or air drying prior to storage is recommended if only moist dust is available.

Circulation of Porcine Parvovirus Types 1 through 6 in Serum Samples Obtained from Six Commercial Polish Pig Farms.

Porcine parvoviruses are small non-enveloped DNA viruses, very resistant to inactivation, and ubiquitous in the global pig population. Porcine parvovirus type 1 (PPV1) has been known since the 1960s and is a major causative agent of reproductive failure in breeding herds. During the last decade, several new parvoviruses have been identified in pigs by molecular methods and have been consecutively designated as PPV2 through PPV6. Epidemiology data for these viruses are limited, and the impact of these newly recognized parvoviruses on pigs is largely unknown. To further generate knowledge on the distribution of PPVs in pigs, a total of 247 serum samples were collected from six commercial Polish pig farms during 2013-2015 and tested by PCR assays and ELISAs. The pigs ranged from two to 18 weeks of age at sample collection. Breeding herds supplying the investigated farms were routinely vaccinated against PPV1. While all growing pig samples were negative for PPV1 DNA, young pigs were frequently negative for PPV1 antibodies and seroconversion to PPV1 was commonly seen at 9-10 weeks of age. The PPV2 antibody detection was highest in young pigs (2-6-week-old) and decreased in older pigs indicating passively acquired antibodies. The DNA prevalence rates in the serum samples analysed were 19% for PPV2, 7.7% for PPV3, 2.4% for PPV4, 4.0% for PPV5 and 6.1% for PPV6. Most PPV DNA-positive samples were identified in 9- to 18-week-old pigs with no obvious association with disease on the farm. All recently emerging PPV genotypes were detected in Polish farms. Similar to previous reports in other pig populations, PPV2 was the most frequent PPV genotype circulating in Poland.

A porcine reproductive and respiratory syndrome virus candidate vaccine based on the synthetic attenuated virus engineering approach is attenuated and effective in protecting against homologous virus challenge.

Current porcine reproductive and respiratory syndrome virus (PRRSV) vaccines sometimes fail to provide adequate immunity to protect pigs from PRRSV-induced disease. This may be due to antigenic differences among PRRSV strains. Rapid production of attenuated farm-specific homologous vaccines is a feasible alternative to commercial vaccines. In this study, attenuation and efficacy of a codon-pair de-optimized candidate vaccine generated by synthetic attenuated virus engineering approach (SAVE5) were tested in a conventional growing pig model. Forty pigs were vaccinated intranasally or intramuscularly with SAVE5 at day 0 (D0). The remaining 28 pigs were sham-vaccinated with saline. At D42, 30 vaccinated and 19 sham-vaccinated pigs were challenged with the homologous PRRSV strain VR2385. The experiment was terminated at D54. The SAVE5 virus was effectively attenuated as evidenced by a low magnitude of SAVE5 viremia for 1-5 consecutive weeks in 35.9% (14/39) of the vaccinated pigs, lack of detectable nasal SAVE5 shedding and failure to transmit the vaccine virus from pig to pig. By D42, all vaccinated pigs with detectable SAVE5 viremia also had detectable anti-PRRSV IgG. Anti-IgG positive vaccinated pigs were protected from subsequent VR2385 challenge as evidenced by lack of VR2385 viremia and nasal shedding, significantly reduced macroscopic and microscopic lung lesions and significantly reduced amount of PRRSV antigen in lungs compared to the non-vaccinated VR2385-challenged positive control pigs. The nasal vaccination route appeared to be more effective in inducing protective immunity in a larger number of pigs compared to the intramuscular route. Vaccinated pigs without detectable SAVE5 viremia did not seroconvert and were fully susceptible to VR2385 challenge. Under the study conditions, the SAVE approach was successful in attenuating PRRSV strain VR2385 and protected against homologous virus challenge. Virus dosage likely needs to be adjusted to induce replication and protection in a higher percentage of vaccinated pigs.

The effects of sow viremia and maternal antibodies in porcine circovirus 2 on viral infection and weight of piglets / Efeito da viremia da porca e de anticorpos maternos para circovírus suíno 2 na infecção e no peso da leitegada

The aim of this study was to characterize the porcine circovirus 2 (PCV2) infections in farrowing sows and to evaluate an association with piglet viremia and weight. Twenty sows and 100 newborn piglets were studied. Colostrum and serum of the sows were obtained on the day of parturition. Milk samples were collected on day 20 postpartum. Blood samples were taken and the piglets were weighed on days 1, 20, 42, 63 and 84 postpartum. Colostrum, milk and serum were evaluated for PCV2 DNA load. Serum was evaluated for neutralizing antibodies. PCV2 DNA was found in 17/20 serum samples, 14/20 colostrum samples and 11/20 milk samples. On day 1 postpartum 29% of piglets were viremic. PCV2 viral load ranged from 3.02 to 6.75 log10 copies/mL considering all sampled days. There was no correlation between sow viremia, antibody levels or PCV2 load in colostrum and piglet viremia on day 1 postpartum. The PCV2 load in colostrum and milk was associated with viremia in piglets from weaning to 84 days postpartum. Piglets' PCV2 viremia and viral load could not be associated with weight throughout this study...

O objetivo deste estudo foi caracterizar o efeito do infecção pelo circovírus suíno 2 (PCV2) em porcas gestantes na viremia e no peso da leitegada. Vinte porcas e 100 leitões recém-nascidos foram acompanhados. Amostras de colostro e soro das porcas foram obtidas no dia do parto. Amostras de leite foram coletadas no dia pós-parto 20. Os leitões foram pesados e tiveram amostras de soro coletadas nos dias um, 20, 42, 63 e 84 pós-parto. Soro, colostro e leite foram testados para carga viral do PCV2. Soro foi avaliado para presença de anticorpos neutralizantes. O DNA do PCV2 foi encontrado em 14 de 20 amostras de colostro e em 11 de 20 amostras de leite. No dia pós-parto 1, 29% dos leitões foram virêmicos. A carga viral do PCV2 variou 3,02-6,75 log10 cópias / mL, considerando todos os dias amostrados. Não houve correlação entre viremia das porcas e os níveis de anticorpos no soro ou na carga de PCV2 no colostro e na viremia dos leitões com um dia de vida. A carga de PCV2 no colostro e no leite foi associada à viremia em leitões do desmame até 84 dias pós-parto. A carga viral do PCV2 em leitões não foi associada com o peso ao longo deste estudo...

Lack of antibody protection against Porcine circovirus 2 and Porcine parvovirus in naturally infected dams and their offspring.

The aim of this study was to evaluate Porcine parvovirus (PPV) and Porcine circovirus 2 (PCV2) infection in dams and their offspring and the role of antibody protection on these infections. Sera were collected from gilts and sows by venipuncture and from umbilical cord of newborn pre-suckle piglets for the detection of PCV2 and PPV antibodies by immunoperoxidase monolayer and haemmaglutination inhibition assays, respectively. Gilts and sows sera were submitted to viral detection by PCR, as well as heart, lung, tonsil and lymph nodes samples from stillborn and mummified fetuses. High antibody titers before artificial insemination (AI) (>5.120 and >2.560 UHA for PCV2 and PPV, respectively), were found associated with viremia and fetal exposure for both PCV2 and PPV, respectively, in gilts and sows, regardless of pregnancy stage. These infections resulted in litters with mummified, stillborn, as well as seropositive and viable newborns. These findings bring new evidence about the lack of antibody protection against PCV2 and PPV infections in dams, indicating that more studies are necessary about the role of humoral response against both pathogens.