Infectivity and pathobiology of H7N1 and H5N8 high pathogenicity avian influenza viruses for pigeons (Columba livia var. domestica).

Avian influenza (AI) is one of the most important viral diseases in poultry, wildlife and humans. Available data indicate that pigeons play a minimum role in the epidemiology of AI. However, a degree of variation exists in the susceptibility of pigeons to highly pathogenic AI viruses (HPAIVs), especially since the emergence of the goose/Guangdong H5 lineage. Here, the pathogenesis of H5N8 HPAIV in comparison with a H7N1 HPAIV and the role of pigeons in the epidemiology of these viruses were evaluated. Local and urban pigeons (Columba livia var. domestica) were intranasally inoculated with 105 ELD50 of A/goose/Spain/IA17CR02699/2017 (H5N8) or A/Chicken/Italy/5093/1999 (H7N1) and monitored during 14 days. Several pigeons inoculated with H5N8 or H7N1 seroconverted. However, clinical signs, mortality, microscopic lesions and viral antigen were only detected in a local pigeon inoculated with H5N8 HPAIV. This pigeon presented prostration and neurological signs that correlated with the presence of large areas of necrosis and widespread AIV antigen in the central nervous system, indicating that the fatal outcome was associated with neurological dysfunction. Viral RNA in swabs was detected in some pigeons inoculated with H7N1 and H5N8, but it was inconsistent, short-term and at low titres. The present study demonstrates that the majority of pigeons were resistant to H5N8 and H7N1 HPAIVs, despite several pigeons developing asymptomatic infections. The limited viral shedding indicates a minimum role of pigeons as amplifiers of HPAIVs, regardless of the viral lineage, and suggests that this species may represent a low risk for environmental contamination. RESEARCH HIGHLIGHTS H7N1 and H5N8 HPAIVs can produce subclinical infections in pigeons. The mortality caused by H5N8 HPAIV in one pigeon was associated with neurological dysfunction. Pigeons represent a low risk for environmental contamination by HPAIVs.

Experimental infection of domestic geese (Anser anser var. domesticus) with H5N8 Gs/GD and H7N1 highly pathogenic avian influenza viruses.

Prior to the emergence of the Asian-origin H5 Goose/Guangdong/1/96 (Gs/GD) lineage, highly pathogenic avian influenza viruses (HPAIV) had rarely caused high mortalities in domestic geese. In 2016/2017 European epidemics, H5N8 Gs/GD clade 2.3.4.4 Group B produced an unprecedented number of outbreaks in waterfowl holdings. In this study, the pathogenesis of H5N8 HPAIV in comparison with H7N1 HPAIV, and the role of domestic geese in the epidemiology of these viruses, were evaluated. Local and commercial geese (Anser anser var. domesticus) were intranasally inoculated with 105 ELD50 of A/goose/Spain/IA17CR02699/2017 (H5N8) or A/Chicken/Italy/5093/1999 (H7N1) and monitored daily during 15 days. H5N8 was highly virulent to domestic geese, reaching 100% mortality by 10 days post-infection. Systemic microscopic necrotizing lesions associated with widespread AIV-antigen were detected by IHC techniques, the central nervous system being the most severely affected. High viral loads, measured by qRT-PCR, were present in all samples collected: oral and cloacal swabs, plasma tissues, and moderate levels in pool water. Domestic geese were also susceptible to H7N1 infection, as demonstrated by seroconversion and detection of viral RNA in tissues and plasma in some geese, but all lacked clinical signs. Viral shedding was confirmed in only some geese and was restricted to the oral route, but levels were high and still detected at the end of the study. Overall, H7N1 presents a lower lethality and shedding than H5N8 in geese; however, the viral shedding indicates that these species could play a role in the epidemiology of Gs/GD and other lineages of HPAIVs. RESEARCH HIGHLIGHTS H5N8 Gs/GD clade 2.3.4.4 Group B is highly virulent to domestic geese. The severity of H5N8 is associated with multisystemic replication. H7N1 can infect domestic geese but is avirulent to this species. Domestic geese could play a role in the epidemiology of Gs/GD HPAIVs.

A novel variant of the infectious bronchitis virus resulting from recombination events in Italy and Spain.

Infectious bronchitis is considered to be one of the most devastating diseases in poultry. Control of its spread is typically attempted through biosecurity measures and extensive vaccination. However, the remarkable genetic and antigenic variability of the virus, which originate from both mutations and recombination events, represents an unsolved challenge for this disease. The present study reports on the emergence and spread of recombinant clusters detected in Italy and Spain between 2012 and 2014. A total of 36 Spanish and Italian infectious bronchitis virus (IBV) field strains were investigated and genetically characterized using phylogenetic, molecular, recombination and selection pressure analyses of the complete S1 gene. Based on the partial S1 sequencing, 27 IBV strains originating from Spain and nine from Italy were initially classified as being closely related to the Guandong/Xindadi (XDN) genotype. Phylogenetic analysis of the complete S1 gene revealed that the XDN strains formed a homogeneous clade with the Spanish IBV isolates within the QX genotype, whereas there was higher variability within the Italian strains. Recombination analysis determined that these strains belonged to four groups, which originated from independent recombination events between the QX and 793B IBV genotypes. Our data support the hypothesis of two different scenarios: firstly, in Spain, the large and homogeneous clade probably originated from a single offspring of the recombinant founder, which became dominant and spread throughout the country. Secondly, the nine Italian recombinants, which are characterized by three different recombination patterns, probably represent less fitted strains, because they were less viable with respect to their recombinant parents.

Six-Year Follow-up of Slaughterhouse Surveillance (2008-2013): The Catalan Slaughterhouse Support Network (SESC).

Meat inspection has the ultimate objective of declaring the meat and offal obtained from carcasses of slaughtered animals fit or unfit for human consumption. This safeguards the health of consumers by ensuring that the food coming from these establishments poses no risk to public health. Concomitantly, it contributes to animal disease surveillance. The Catalan Public Health Protection Agency (Generalitat de Catalunya) identified the need to provide its meat inspectors with a support structure to improve diagnostic capacity: the Slaughterhouse Support Network (SESC). The main goal of the SESC was to offer continuing education to meat inspectors to improve the diagnostic capacity for lesions observed in slaughterhouses. With this aim, a web-based application was designed that allowed meat inspectors to submit their inquiries, images of the lesions, and samples for laboratory analysis. This commentary reviews the cases from the first 6 years of SESC operation (2008-2013). The program not only provides continuing education to inspectors but also contributes to the collection of useful information on animal health and welfare. Therefore, SESC complements animal disease surveillance programs, such as those for tuberculosis, bovine cysticercosis, and porcine trichinellosis, and is a powerful tool for early detection of emerging animal diseases and zoonoses.

Effectiveness and safety of a treatment regimen based on isoniazid plus vaccination with Mycobacterium tuberculosis cells' fragments: field-study with naturally Mycobacterium caprae-infected goats.

The identification of a herd of goats with tuberculosis let us test a new treatment regimen against latent tuberculosis infection (LTBI). Using large animal experimental models allows a better approach to understanding human tuberculosis according to immunopathological parameters. Based on an initial study showing a correlation between the ESAT-6-specific interferon (IFN)-gamma secretion and the severity of pulmonary lesions, this parameter was used in combination with an X-ray examination to screen the animals to be included in the efficacy and safety studies. All the animals proved to be infected with Mycobacterium caprae. The efficacy study was run in animals distributed in three experimental groups according to treatment: untreated (CT), treated with isoniazid (INH), and treated with INH + RUTI (a vaccine based on M. tuberculosis cell fragments) inoculated twice. RUTI temporarily increased the IFN-gamma production after stimulating the peripheral blood with ESAT-6, purified protein derivative and RUTI in vitro. The INH chemotherapy reduced both pulmonary and extra pulmonary affectation, but not disease in pulmonary lymph nodes. The addition of RUTI may have decreased extrapulmonary disease further but had no benefit to lung or lung lymph-nodes itself. Safety studies showed that inoculation of RUTI caused a temporary increase of rectal temperature (1-2 degrees C) and local swelling, both adverse effects being well tolerated. Neither systemic toxicity nor mortality was induced by the vaccination. The control of goats' infection by the therapeutic regimen consisting in INH chemotherapy + RUTI as well as its safety, represented a further step towards testing its effects in human LTBI in a future.

A proposal on porcine circovirus type 2 (PCV2) genotype definition and their relation with postweaning multisystemic wasting syndrome (PMWS) occurrence.

Porcine circovirus type 2 (PCV2) is the essential infectious agent of postweaning multisystemic wasting syndrome (PMWS). Despite first sequencing studies did not find any association between PCV2 sequences and PMWS occurrence, recent works have suggested the opposite. In the present study, 87 open reading frame 2 (ORF2) sequences obtained from pigs with different clinical conditions and coming from farms with different PMWS status were analyzed. Results further confirmed the existence of two genogroups and the definition of two PCV2 genotypes (1 and 2) is proposed. All sequences included in genotype 1 came from pigs from PMWS affected farms, while all sequences obtained from non-PMWS affected farms corresponded to genotype 2. Moreover, infection of single pigs from PMWS affected farms harbouring both genotypes is described. Present results suggest that PCV2 genotype 1 may potentially be more pathogenic than PCV2 genotype 2.

Non-linear quantization error reduction for the temperature measurement subsystem on-board LISA Pathfinder.

Laser Interferometer Space Antenna (LISA) Pathfinder is a mission to test the technology enabling gravitational wave detection in space and to demonstrate that sub-femto-g free fall levels are possible. To do so, the distance between two free falling test masses is measured to unprecedented sensitivity by means of laser interferometry. Temperature fluctuations are one of the noise sources limiting the free fall accuracy and the interferometer performance and need to be known at the ∼10 µK Hz-1/2 level in the sub-millihertz frequency range in order to validate the noise models for the future space-based gravitational wave detector LISA. The temperature measurement subsystem on LISA Pathfinder is in charge of monitoring the thermal environment at key locations with noise levels of 7.5 µK Hz-1/2 at the sub-millihertz. However, its performance worsens by one to two orders of magnitude when slowly changing temperatures are measured due to errors introduced by analog-to-digital converter non-linearities. In this paper, we present a method to reduce this effect by data post-processing. The method is applied to experimental data available from on-ground validation tests to demonstrate its performance and the potential benefit for in-flight data. The analog-to-digital converter effects are reduced by a factor between three and six in the frequencies where the errors play an important role. An average 2.7 fold noise reduction is demonstrated in the 0.3 mHz-2 mHz band.

Dynamics of Haemophilus parasuis genotypes in a farm recovered from an outbreak of Glässer's disease.

Haemophilus parasuis is a colonizer of the upper respiratory tract of pigs, although it is better known as the etiological agent of Glässer's disease. Interestingly, several strains can be isolated from a single farm, as determined by both genotyping and serotyping. However, it is not known how an outbreak and the subsequent treatment affect the population of H. parasuis strains. In this study, a farm was studied during an outbreak of Glässer's disease and 1 year after antimicrobial treatment and elimination of clinical signs. Bacterial isolation was attempted from nasal swabs and lesions. After isolation, antimicrobial susceptibility, serotype and genotype were determined. Two different genotyping techniques, enterobacterial repetitive intergenic consensus (ERIC)-PCR and multilocus sequence typing (MLST) were used. The H. parasuis strain that was isolated from lesions during the disease outbreak clustered with other virulent strains by both MLST and serotyping analysis. Nasal isolates were included in the corresponding nasal cluster by MLST, but they presented high variability by serotyping. These nasal isolates included serotypes previously classified as virulent and non-virulent. Finally, we found that during the antimicrobial treatment the diversity of strains isolated in the farm was affected and just one strain, which was resistant to the treatment, was detected. One year after the treatment strain diversity was back to normal (three strains).

Chronological study of Mycoplasma hyopneumoniae infection, seroconversion and associated lung lesions in vaccinated and non-vaccinated pigs.

A field trial was conducted to study Mycoplasma hyopneumoniae (Mh) infection dynamics by nested polymerase chain reaction (nPCR) and serology in pigs of a farm affected by enzootic pneumonia (EP). Moreover, correlation of Mh detection at different respiratory tract sites with presence of EP gross and microscopic lung lesions was assessed. These parameters were studied and compared between vaccinated (two doses at 1 and 3 weeks of age versus one dose at 6 weeks of age) and non-vaccinated pigs. Animals were monitored from birth to slaughter by nPCR from nasal swabs and by serology. From 3 to 22 weeks of age, an average of three pigs per treatment and per batch were necropsied (n = 302). The remaining pigs were sent to the slaughter (n = 103). Nasal, bronchial and tonsillar swabs were taken from the necropsied/slaughtered pigs; gross and microscopic EP-suggestive lung lesions were also assessed. Single and double vaccination resulted in earlier seroconversion and higher percentage of Mh seropositive pigs compared to control group. At slaughter, double vaccinated pigs showed lower percentage of EP-compatible gross lung lesions and lower Mh prevalence at upper respiratory tract sites (nasal cavity and tonsil) than control pigs.

Exploratory field study on Mycoplasma hyopneumoniae infection in suckling pigs.

The present study focused on Mycoplasma hyopneumoniae (M. hyopneumoniae) detection by nPCR in nasal swabs of 507 suckling pigs. These animals came from 69 sows (from 1 to 8 parity number) of a farrow-to-finish herd with Enzootic Pneumonia (EP) problems at finishing stages. At 1 and 3 weeks of age (still in the farrowing units), nasal swabs and blood samples were taken from all piglets. Moreover, from these 507 animals, 37 randomly selected pigs were necropsied at 3 weeks of age. From those necropsied pigs, M. hyopneumoniae presence was tested in bronchial and tonsillar swabs. At 1 week post-farrowing, blood samples from sows were collected and used to detect M. hyopneumoniae antibodies. From the 69 analysed sows, 19 (27.5%) were seropositive. Global percentage of pigs with M. hyopneumoniae detection in nasal swabs at 1 and 3 weeks of age was 1.5% (8 out of 507) and 3.8% (19 out of 507), respectively. From these nPCR positive pigs, 89% (24 out of 27) were seronegative and 11% were seropositive. From necropsied animals, the pathogen DNA was detected in two pigs at bronchus level and in another pig at tonsil. In this study, sow parity was not statistically related with sow seropositivity and piglet colonization. These results confirm that M. hyopneumoniae infection may be detected not only in nasal cavities of naturally infected suckling piglets but also at their low respiratory tract airways. Our results suggest that M. hyopneumoniae detection in lower and upper respiratory tract could be an indicator that respiratory problems associated to EP may start relatively early in the production system. In consequence, sow-to-piglet and/or piglet-to piglet transmission in farrowing barns should not be underestimated.

Thermal diagnostics front-end electronics for LISA Pathfinder.

Precision temperature measurements are required in the LTP, the LISA technology package, for various diagnostics objectives. In this article, we describe in detail the front-end electronics design and the associated temperature sensors to achieve the LTP requirements: noise equivalent temperature of 10 microK Hz(-12) in the frequency range from 1 to 30 mHz at room temperature. We designed an ac Wheatstone bridge and a subsequent digital demodulation to minimize 1/f noise. We show experimental results where the required sensitivity in the measurement bandwidth is fulfilled.

Transmission of Porcine reproductive and respiratory syndrome virus 1 to and from vaccinated pigs in a one-to-one model.

The present study examined transmission by contact of Porcine reproductive and respiratory syndrome virus (PRRSV) 1 in a one-to-one model to vaccinated and unvaccinated pigs and from vaccinated infected pigs to other vaccinated pigs. The experiment started by randomly assigning weaned pigs to groups V (n=24) and U (n=26). V pigs were vaccinated with a commercial live attenuated PRRSV vaccine and the U animals were kept as unvaccinated controls. Twenty-eight days later, 6U pigs were separated and allocated in individual boxes. The remaining 20U pigs were intranasally inoculated with PRRSV isolate 3267 (from now on designated as seeder (S) pigs) and 48h later were distributed in boxes where they were commingled with either V or U pigs in 1:1 groups (first contact phase), resulting in 6S:U and 14S:V pairs. As soon as a V pig was detected to be viremic because of contact with a S, the infected V (from now on designated as Vinf) was transferred (<24h after detection) to a new pen where it was comingled with a new V pig (designated as V2) in a second contact phase. For the first contact phase, pigs were maintained 21days at maximum and for the second contact phase the maximum exposure period was 14days. Two V pigs tested positive for the vaccine virus (>99.5% similarity) when they were relocated with the corresponding V2 pigs and they were removed; thus, only 12Vinf were finally considered. All V pigs (12/12) exposed to S animals became infected although the first detection of viremia occurred at 13.6±3.6days, one week later than in U (p<0.05). Also, duration of viremia was shorter for Vinf compared to U, (5.5±4.3days versus 12.5±2.7days). The Vinf group showed remarkable individual variability: eight animals had a viremic period of 5 or less days (3.0±1.4) while the remaining four had a longer viremic period of more than one week (10.8±2.9). This situation was not observed in U. In the second contact phase, transmission from Vinf to V2 pigs occurred in 7/8 cases (87.5%). The mean duration of viremia for V2 was 4.8±3.4 and two different patterns were again observed: two animals had viremias of 9-10days and the rest averaged 3.0±1.4days (range: 2-5days). Vaccinated groups Vinf and V2 had a significantly lower PRRSV shedding in oral fluids for at least the first 9days after the onset of the viremia compared to U, and shedding for V2 was even significantly lower (p<0.05) than shedding for Vinf. Our experimental design reproduced the worst-case scenario for evaluating the effect of vaccination and, under such conditions; it was still efficacious in slowering PRRSV transmission and decreasing the global viral load and particularly oral shedding.

Changes in peripheral blood leukocyte populations in pigs with naturally occurring exudative epidermitis.

The objective of the study was to analyze changes in peripheral blood leukocyte subsets in cases of naturally occurring exudative epidermitis (EE) in pigs. Five of ten piglets developed the chronic clinical form of EE 2-5 days after weaning (PW). Blood samples were obtained at 7, 14 and 21 days from both normal and clinically affected piglets for routine haematology and for the determination of CD45, CD21, CD4, CD8 and gammadeltaTCR cell markers by flow cytometry. When compared with clinically normal piglets EE affected pigs showed significantly decreased values of monocytes at 14 and 21 days PW, and increased numbers of neutrophils and leukocytes at 21 days PW. The EE affected pigs also had an early significant CD4(+) and CD8(high+) T lymphocyte proliferative response at 7 days PW. However affected pigs had a significantly reduced number of B (CD21(+)) and gammadeltaTCR(+) T lymphocytes in blood at 21 days PW. Although all values remained within the normal range, the significant differences in some peripheral blood leukocyte subsets between the two groups of piglets suggest that the generalised cutaneous infection with Staphylococcus hyicus is severe enough to induce a systemic inflammatory and immune responses.

Virological and serological characterization of vaccinated and non-vaccinated piglet subpopulations coming from vaccinated and non-vaccinated sows.

The present study describes the virological and serological profiles of PCV2 vaccinated (V) and non-vaccinated (NV) piglet subpopulations coming from V and NV sows in a PCV2 subclinically infected farm. Four hundred seventy-six piglets born from V or NV sows were further subdivided in a total of four groups: NV sows-NV pigs (NV-NV), NV sows-V pigs (NV-V); V sows-NV pigs (V-NV) and V sows-V pigs (V-V). Seventy-five pigs were randomly selected at the beginning of the trial from each group and they were bled at 4, 8, 12, 16, 21 and 25 weeks of age. All animals included in the trial were weighed at 4 and 25 weeks of age and their average daily weight gain (ADWG) was calculated. Serum samples obtained at different time points were used to assess PCV2 infection (viremia) and the level of antibodies by means of immunoperoxidase monolayer assay (IPMA) against this pathogen. IPMA titers (classified in high, medium or low) and PCR results (positive or negative) were analyzed using a multiple correspondence and K-means cluster analysis. According to these tests, animals included in the study were classified into the following four clusters: (1) 93 piglets that were viremic mainly from 12 to 25 weeks of age and with PCV2 antibody titers increasing over time; (2) 75 piglets with late PCV2 infection and seroconversion (later than 16 weeks of age); (3) 26 piglets with high but decreasing PCV2 antibody titers and low percentages of PCV2 PCR positive serum samples; and (4) 105 piglets with medium and high IPMA titers throughout the trial and sporadic PCR positive samples. The defined subpopulations of piglets were observed in all experimental groups (NV-NV, NV-V, V-NV and V-V) although in variable percentages. Thus, animals from clusters 1 and 2 belonged mainly to the NV-NV and V-NV groups and animals from clusters 3 and 4 were distributed mainly into the NV-V and V-V groups. Finally, the ADWG of pigs belonging to clusters 3 and 4 was significantly higher (p=0.02) than that of pigs belonging to clusters 1 and 2. Within each cluster, no statistically significant differences were found in ADWG between treatment groups.

Apoptosis in normal lymphoid organs from healthy normal, conventional pigs at different ages detected by TUNEL and cleaved caspase-3 immunohistochemistry in paraffin-embedded tissues.

The frequency and the distribution of apoptotic cells were investigated in formalin-fixed paraffin-embedded lymphoid tissues from healthy conventional pigs at four different ages (6 days, 2 months, 3.5 months and 5 months). Samples of tonsil, mesenteric lymph node, spleen, thymus and Peyer's patches were histologically processed and apoptosis evaluated with the TUNEL reaction and cleaved caspase-3 immunohistochemistry. In each technique, quantification of positive labelling was done for each particular lymphoid tissue area. The labelling pattern and distribution were similar for TUNEL and cleaved caspase-3. TUNEL stained mainly apoptotic bodies inside macrophages, but signal was also seen in free apoptotic bodies and in the nuclei of lymphocyte-like cells. The anti-cleaved caspase-3 antibody labelled mainly nuclei of lymphocyte-like cells. All tissues presented a similar distribution pattern of apoptosis, except for the 6-day-old group. In this group, a scattered distribution of positive cells was detected in tonsil, lymph node and spleen. In the tonsil and mesenteric lymph nodes from the older pigs, follicular areas presented higher amounts of positive cells than interfollicular areas. Moreover, the splenic white pulp showed more positive reaction than the red pulp, especially when they included germinal centres. In all groups, the follicular areas of ileal Peyer's patches presented more labelled cells than the dome and the lamina propria. In the thymus, the higher apoptotic rates were found in the cortex. In general, TUNEL yielded higher rates of positive cells than cleaved caspase-3 immunolabelling. A good correlation between the two techniques was found for thymus, tonsil and mesenteric lymph node, but not for Peyer's patches and spleen. This study describes a detailed histochemical characterization of apoptosis in pig lymphoid tissues using TUNEL and a cleaved caspase-3 immunolabelling at different ages. Moreover, our results indicate that TUNEL and cleaved caspase-3 techniques can be equivalent only when tissues have a high or low levels of apoptosis, since a considerable discrepancy was found in intermediate situations. Data from this study should be useful for future comparative studies under disease conditions.

Effect of porcine circovirus type 2 (PCV2) load in serum on average daily weight gain during the postweaning period.

Porcine circovirus type 2 (PCV2) is a ubiquitous virus that mainly affects nursery and fattening pigs causing systemic disease (PCV2-SD) or subclinical infection. A characteristic sign in both presentations is reduction of average daily weight gain (ADWG). The present study aimed to assess the relationship between PCV2 load in serum and ADWG from 3 (weaning) to 21 weeks of age (slaughter) (ADWG 3-21). Thus, three different boar lines were used to inseminate sows from two PCV2-SD affected farms. One or two pigs per sow were selected (60, 61 and 51 piglets from Pietrain, Pietrain×Large White and Duroc×Large White boar lines, respectively). Pigs were bled at 3, 9, 15 and 21 weeks of age and weighted at 3 and 21 weeks. Area under the curve of the viral load at all sampling times (AUCqPCR 3-21) was calculated for each animal according to standard and real time quantitative PCR results; this variable was categorized as "negative or low" (<10(4.3) PCV2 genome copies/ml of serum), "medium" (≥10(4.3) to ≤10(5.3)) and "high" (>10(5.3)). Data regarding sex, PCV2 antibody titre at weaning and sow parity was also collected. A generalized linear model was performed, obtaining that paternal genetic line and AUCqPCR 3-21 were related to ADWG 3-21. ADWG 3-21 (mean±typical error) for "negative or low", "medium" and "high" AUCqPCR 3-21 was 672±9, 650±12 and 603±16 g/day, respectively, showing significant differences among them. This study describes different ADWG performances in 3 pig populations that suffered from different degrees of PCV2 viraemia.

Humoral response and colostral antibody transfer following 'one-dose' pre-mating vaccination of sows against porcine circovirus type-2.

The objective of this study was to investigate the presence of porcine circovirus type 2 (PCV2) DNA and antibody to the virus in the serum and colostrum of sows vaccinated prior to mating and in their offspring. Seventy-seven sows were randomly distributed into vaccinated (V, n=36) and non-vaccinated (NV, n=41) groups. One week before mating, sows were given a PCV2 vaccine (V group) or PBS (NV group) IM. Blood samples were taken from the sows at fixed time-points and colostrum samples were taken at farrowing. Blood samples were also taken from the piglets of the sows at 4 weeks of age. The results indicated that vaccination prior to mating elicited a strong, homogeneous humoral response and, in consequence, more homogeneous colostral PCV2 antibody concentrations.

Simultaneous porcine circovirus type 2 and Mycoplasma hyopneumoniae co-inoculation does not potentiate disease in conventional pigs.

The aim of this study was to assess the effect of simultaneous experimental inoculation of porcine circovirus type 2 (PCV2; intranasal delivery) and Mycoplasma hyopneumoniae (Mhyo; transtracheal delivery) into conventional, seropositive 6-week-old piglets. Thirty-six male piglets were assigned randomly to four groups: control (n=6), PCV2 (n=6), Mhyo (n=12) and PCV2+Mhyo (n=12). Blood samples and faecal and nasal swabs were collected at 0, 7, 14 and 21 days post inoculation (dpi). No significant clinical signs attributable to PCV2 infection were observed during the experiment. Coughing was recorded in three pigs from the Mhyo group and six from the PCV2+Mhyo group. No significant differences in mean body weight and rectal temperature were observed between the groups. Mild microscopical lesions similar to those reported for post-weaning multisystemic wasting syndrome were observed in two PCV2 pigs and in one PCV2+Mhyo animal. Mhyo-compatible lung lesions were observed in 21/24 pigs inoculated with Mhyo (10 from the Mhyo group and 11 from the PCV2+Mhyo group). PCV2 was detected by in-situ hybridization in 3/12 PCV2 and in 4/12 PCV2+Mhyo animals. No significant differences in PCV2 load (serum and nasal and faecal swabs), duration of viraemia or antibody titre were detected between PCV2-inoculated groups. No significant differences in Mhyo load in nasal swabs, percentage of Mhyo-seropositive pigs and mean lung score was detected between Mhyo-inoculated groups. Under the conditions of the present study, concurrent inoculation of PCV2 and Mhyo did not result in potentiation of clinical signs and lesions attributed to either infection.

Enhancing DNA immunization by targeting ASFV antigens to SLA-II bearing cells.

One of the main criticisms to DNA vaccines is the poor immunogenicity that they confer on occasions, at least in large animals. Confirming this theory, immunization with plasmid DNA encoding two African swine fever virus genes in frame (pCMV-PQ), failed in inducing detectable immune responses in pigs, while it was successful in mice. Aiming to improve the immune responses induced in swine, a new plasmid was constructed, encoding the viral genes fused in frame with a single chain variable fragment of an antibody specific for a swine leukocyte antigen II (pCMV-APCH1PQ). Our results clearly demonstrate that targeting antigens to antigen professional cells exponentially enhanced the immune response induced in pigs, albeit that the DNA vaccine was not able to confer protection against lethal viral challenge. Indeed, a viremia exacerbation was observed in each of the pigs that received the pCMV-APCH1PQ plasmid, this correlating with the presence of non-neutralizing antibodies and antigen-specific SLA II-restricted T-cells. The implications of our discoveries for the development of future vaccines against African swine fever virus and other swine pathogens are discussed.

Risk factors associated with pleuritis and cranio-ventral pulmonary consolidation in slaughter-aged pigs.

Examination of lung lesions at the slaughterhouse is a useful tool to estimate the importance of respiratory disease at farm, regional or national level. The objective of the present work was to describe the prevalence of gross lung lesions at slaughter, with a special focus on pleuritis and cranio-ventral pulmonary consolidation, and to identify major risk factors for these lesions. Data from 107 farms involving approximately 11,000 pigs enabled gross lung lesions to be correlated with serology to different swine respiratory pathogens as well as with production system characteristics and vaccination schedules. Pleuritis and cranio-ventral pulmonary consolidation lesions were recorded in 26.8% and 55.7% of slaughter-aged pigs, respectively. Among lungs with pleuritis, 50.1% had lesions compatible with Actinobacillus pleuropneumoniae (App) infection. Antibodies to porcine reproductive and respiratory syndrome (PRRSV), three subtypes (H1N1, H1N2 and H3N2) of swine influenza virus (SIV), App and Mycoplasma hyopneumoniae (Mhyo) were highly prevalent (>82%) in most of the farms. In a multivariable analysis, it was estimated (R(2)=0.40) that the percentage of animals with pleuritis compatible with App infection depended on the existence of an all in-all out by room management system and App and PRRSV herd seroprevalence. Moreover, it was possible to foresee (R(2)=0.59) that cranio-ventral pulmonary consolidation lesions (EP-like lesions) were affected by the type of farm ventilation, the presence of respiratory symptoms during the fattening period and Mhyo and SIV H1N2 herd seroprevalence.