Highly Pathogenic Avian Influenza A(H5N1) Clade 2.3.4.4b Virus Infection in Domestic Dairy Cattle and Cats, United States, 2024.

We report highly pathogenic avian influenza A(H5N1) virus in dairy cattle and cats in Kansas and Texas, United States, which reflects the continued spread of clade 2.3.4.4b viruses that entered the country in late 2021. Infected cattle experienced nonspecific illness, reduced feed intake and rumination, and an abrupt drop in milk production, but fatal systemic influenza infection developed in domestic cats fed raw (unpasteurized) colostrum and milk from affected cows. Cow-to-cow transmission appears to have occurred because infections were observed in cattle on Michigan, Idaho, and Ohio farms where avian influenza virus-infected cows were transported. Although the US Food and Drug Administration has indicated the commercial milk supply remains safe, the detection of influenza virus in unpasteurized bovine milk is a concern because of potential cross-species transmission. Continued surveillance of highly pathogenic avian influenza viruses in domestic production animals is needed to prevent cross-species and mammal-to-mammal transmission.

Sialic Acid Receptor Specificity in Mammary Gland of Dairy Cattle Infected with Highly Pathogenic Avian Influenza A(H5N1) Virus.

In March 2024, the US Department of Agriculture's Animal and Plant Health Inspection Service reported detection of highly pathogenic avian influenza (HPAI) A(H5N1) virus in dairy cattle in the United States for the first time. One factor that determines susceptibility to HPAI H5N1 infection is the presence of specific virus receptors on host cells; however, little is known about the distribution of the sialic acid (SA) receptors in dairy cattle, particularly in mammary glands. We compared the distribution of SA receptors in the respiratory tract and mammary gland of dairy cattle naturally infected with HPAI H5N1. The respiratory and mammary glands of HPAI H5N1-infected dairy cattle are rich in SA, particularly avian influenza virus-specific SA α2,3-gal. Mammary gland tissues co-stained with sialic acids and influenza A virus nucleoprotein showed predominant co-localization with the virus and SA α2,3-gal. HPAI H5N1 exhibited epitheliotropism within the mammary gland, and we observed rare immunolabeling within macrophages.

Detection and disease diagnosis trends (2017-2022) for Streptococcus suis, Glaesserella parasuis, Mycoplasma hyorhinis, Actinobacillus suis and Mycoplasma hyosynoviae at Iowa State University Veterinary Diagnostic Laboratory.

BACKGROUND: Accurate measurement of disease associated with endemic bacterial agents in pig populations is challenging due to their commensal ecology, the lack of disease-specific antemortem diagnostic tests, and the polymicrobial nature of swine diagnostic cases. The main objective of this retrospective study was to estimate temporal patterns of agent detection and disease diagnosis for five endemic bacteria that can cause systemic disease in porcine tissue specimens submitted to the Iowa State University Veterinary Diagnostic Laboratory (ISU VDL) from 2017 to 2022. The study also explored the diagnostic value of specific tissue specimens for disease diagnosis, estimated the frequency of polymicrobial diagnosis, and evaluated the association between phase of pig production and disease diagnosis. RESULTS: S. suis and G. parasuis bronchopneumonia increased on average 6 and 4.3%, while S. suis endocarditis increased by 23% per year, respectively. M. hyorhinis and A. suis associated serositis increased yearly by 4.2 and 12.8%, respectively. A significant upward trend in M. hyorhinis arthritis cases was also observed. In contrast, M. hyosynoviae arthritis cases decreased by 33% average/year. Investigation into the diagnostic value of tissues showed that lungs were the most frequently submitted sample, However, the use of lung for systemic disease diagnosis requires caution due to the commensal nature of these agents in the respiratory system, compared to systemic sites that diagnosticians typically target. This study also explored associations between phase of production and specific diseases caused by each agent, showcasing the role of S. suis arthritis in suckling pigs, meningitis in early nursery and endocarditis in growing pigs, and the role of G. parasuis, A. suis, M. hyorhinis and M. hyosynoviae disease mainly in post-weaning phases. Finally, this study highlighted the high frequency of co-detection and -disease diagnosis with other infectious etiologies, such as PRRSV and IAV, demonstrating that to minimize the health impact of these endemic bacterial agents it is imperative to establish effective viral control programs. CONCLUSIONS: Results from this retrospective study demonstrated significant increases in disease diagnosis for S. suis, G. parasuis, M. hyorhinis, and A. suis, and a significant decrease in detection and disease diagnosis of M. hyosynoviae. High frequencies of interactions between these endemic agents and with viral pathogens was also demonstrated. Consequently, improved control programs are needed to mitigate the adverse effect of these endemic bacterial agents on swine health and wellbeing. This includes improving diagnostic procedures, developing more effective vaccine products, fine-tuning antimicrobial approaches, and managing viral co-infections.

Streptococcus gallolyticus and Bacterial Endocarditis in Swine, United States, 2015-2020.

To evaluate trends in bacterial causes of valvular endocarditis in swine, we retrospectively analyzed 321 cases diagnosed at Iowa State University Veterinary Diagnostic Laboratory (Ames, IA, USA) during May 2015--April 2020. Streptococcus gallolyticus was the causative agent for 7.59% of cases. This emerging infection in swine could aid study of endocarditis in humans.

IDENTIFICATION AND CORRELATION OF A NOVEL SIADENOVIRUS IN A FLOCK OF BUDGERIGARS (MELOPSITTACUS UNDULATES) INFECTED WITH SALMONELLA TYPHIMURIUM IN THE UNITED STATES.

A flock of budgerigars (Melopsittacus undulates) was purchased from a licensed breeder and quarantined at a zoologic facility within the United States in 2016. Following 82 deaths within the flock, the remaining 66 birds were depopulated because of ongoing clinical salmonellosis despite treatment. Gross necropsy was performed on all 66 birds. Histopathologic examination was performed on 10 birds identified with gross lesions and 10 birds without. Pathologic findings were most often observed in the liver, kidney, and spleen. Lesions noted in the livers and spleens were consistent with published reports of salmonellosis in psittacine species. Multisystemic changes associated with septicemia were not noted, most likely because of antibiotic intervention before euthanasia. Of the 20 budgerigars evaluated by histopathology, six had large basophilic intranuclear inclusion bodies within tubular epithelia in a portion of the kidneys. Electronic microscopy, next-generation sequencing, Sanger sequencing, and phylogenetic analyses were used to identify and categorize the identified virus as a novel siadenovirus strain BuAdV-1 USA-IA43444-2016. The strain was 99% similar to budgerigar adenovirus 1 (BuAdV-1), previously reported in Japan, and to a psittacine adenovirus 5 recently identified in a U.S. cockatiel. Salmonella typhimurium carriers were identified via polymerase chain reaction (PCR) and bacterial culture and compared with viral carriers identified via PCR. Inclusion bodies and Salmonella detection were significant in birds with gross lesions versus those without; however, there was no correlation between budgerigars positive with siadenovirus by PCR and concurrent Salmonella infection. Identifying subclinical siadenovirus strain BuAdV-1 USA-IA43444-2016 infection in this flock significantly differs from a previous report of clinical illness in five budgerigars resulting in death caused by BuAdV-1 in Japan. S. typhimurium remains a significant pathogen in budgerigars, and zoonotic concerns prompted depopulation to mitigate the public health risks of this flock.

Severe Disseminated Necrotizing and Granulomatous Lymphadenitis and Encephalitis in a Dog Due to Sporotrichum pruinosum (Teleomorph: Phanerochaete chrysosporium).

A 9-year-old female mixed breed dog presented for an acute onset of anorexia, vomiting, and cough. Initial examination and diagnostics revealed a large multilobular cranial mediastinal mass with unidentified fungal organisms on cytology. The disease progressed in spite of therapy until the dog was euthanized 8 months later. Gross necropsy findings were a large multilobular intrathoracic mass, mild pleuritis, and generalized lymphadenopathy. Histologic evaluation showed granulomatous inflammation and necrosis with numerous 20- to 70-micron, periodic acid-Schiff- and Gomori methenamine silver-positive spherules effacing lymph node parenchyma, as well as severe inflammation within the midbrain. Endosporulation was a common finding, and large numbers of fungal hyphae were also present in affected areas. Ribosomal RNA gene sequencing found 100% identity to published sequences of Phanerochaete chrysosporium, the teleomorph form of Sporotrichum pruinosum. This is the first published report of disease caused by natural infection with this basidiomycete organism in animals.

Evaluation of serological cross-reactivity and cross-neutralization between the United States porcine epidemic diarrhea virus prototype and S-INDEL-variant strains.

BACKGROUND: At least two genetically different porcine epidemic diarrhea virus (PEDV) strains have been identified in the United States (U.S. PEDV prototype and S-INDEL-variant strains). The current serological assays offered at veterinary diagnostic laboratories for detection of PEDV-specific antibody are based on the U.S. PEDV prototype strain. The objectives of this study were: 1) isolate the U.S. PEDV S-INDEL-variant strain in cell culture; 2) generate antisera against the U.S. PEDV prototype and S-INDEL-variant strains by experimentally infecting weaned pigs; 3) determine if the various PEDV serological assays could detect antibodies against the U.S. PEDV S-INDEL-variant strain and vice versa. RESULTS: A U.S. PEDV S-INDEL-variant strain was isolated in cell culture in this study. Three groups of PEDV-negative, 3-week-old pigs (five pigs per group) were inoculated orally with a U.S. PEDV prototype isolate (previously isolated in our lab), an S-INDEL-variant isolate or virus-negative culture medium. Serum samples collected at 0, 7, 14, 21 and 28 days post inoculation were evaluated by the following PEDV serological assays: 1) indirect fluorescent antibody (IFA) assays using the prototype and S-INDEL-variant strains as indicator viruses; 2) virus neutralization (VN) tests against the prototype and S-INDEL-variant viruses; 3) PEDV prototype strain whole virus based ELISA; 4) PEDV prototype strain S1-based ELISA; and 5) PEDV S-INDEL-variant strain S1-based ELISA. The positive antisera against the prototype strain reacted to and neutralized both prototype and S-INDEL-variant viruses, and the positive antisera against the S-INDEL-variant strain also reacted to and neutralized both prototype and S-INDEL-variant viruses, as examined by IFA antibody assays and VN tests. Antibodies against the two PEDV strains could be detected by all three ELISAs although detection rates varied to some degree. CONCLUSIONS: These data indicate that the antibodies against U.S. PEDV prototype and S-INDEL-variant strains cross-reacted and cross-neutralized both strains in vitro. The current serological assays based on U.S. PEDV prototype strain can detect antibodies against both U.S. PEDV strains.

An experimental universal swine influenza a virus (IAV) vaccine candidate based on the M2 ectodomain (M2e) peptide does not provide protection against H1N1 IAV challenge in pigs.

Swine flu is a common disease problem in North American pig populations and swine influenza A viruses (IAV) are extremely diverse and the lack of cross protection between heterologous strains is impacting vaccine efficacy in the field. The objective of this study was to design and test a novel swine flu vaccine targeting the M2 ectodomain (M2e) of IAV, a highly conserved region within the IAV proteome. In brief, an M2e peptide was designed to match the predominant swine IAV M2 sequence based on global analysis of sequences from pigs and humans. The resulting sequence was used to synthesize the M2e peptide coupled to a carrier protein. The final vaccine concentration was 200 µg per dose, and a commercial, microemulsion-based aqueous adjuvant was added. Nine 3-week-old IAV negative piglets were randomly assigned to three groups and rooms including non-vaccinated pigs (NEG-CONTROLs) and vaccinated pigs using the intramuscular (M2e-IM) or the intranasal route (M2e-IN). Vaccinations were done at weaning and again at 2 weeks later. An in-house enzyme-linked immunosorbent assay (ELISA) was developed and validated to study the M2e IgG antibody response and demonstrated M2e-IM pigs had a higher systemic antibody response compared to M2e-IN pigs. Subsequently, an IAV challenge study was conducted. The results indicated that M2e-IM vaccinated pigs were not protected from H1N1 (US pandemic clade, global clade 1A.3.3.2) challenge despite having a strong humoral anti-M2e immune response. In conclusion, while the experimental IAV vaccine was able to induce anti-M2e antibodies, when challenged with H1N1, the vaccinated pigs were not protected, perhaps indicating that reactivity to the M2e antigen alone is not sufficient to reduce clinical signs, lesions or shedding associated with experimental IAV challenge.

Genomic characterization of highly pathogenic avian influenza A H5N1 virus newly emerged in dairy cattle.

In March 2024, the emergence of highly pathogenic avian influenza (HPAI) A (H5N1) infections in dairy cattle was detected in the United Sates for the first time. We genetically characterize HPAI viruses from dairy cattle showing an abrupt drop in milk production, as well as from two cats, six wild birds, and one skunk. They share nearly identical genome sequences, forming a new genotype B3.13 within the 2.3.4.4b clade. B3.13 viruses underwent two reassortment events since 2023 and exhibit critical mutations in HA, M1, and NS genes but lack critical mutations in PB2 and PB1 genes, which enhance virulence or adaptation to mammals. The PB2 E627 K mutation in a human case associated with cattle underscores the potential for rapid evolution post infection, highlighting the need for continued surveillance to monitor public health threats.

Diagnosis of Anaplasma marginale in cattle at the Iowa State University veterinary diagnostic laboratory 2003-2021.

Anaplasma marginale is a blood-borne rickettsia-like organism that infects cattle erythrocytes and causes anaplasmosis. This study reviews diagnostic data of all A. marginale diagnostics performed from 2003 to August 2021 in the Iowa State Veterinary Diagnostic Laboratory. Typically, the referring veterinarian's initial tentative diagnosis was based on presenting clinical signs or necropsy findings. Confirmatory testing at the ISU-VDL consisted of light microscopy evaluation of stained blood smears or molecular diagnostic procedures. A total of 94 cases were submitted with tissue samples from deceased animals, of which 79 were from Iowa and 15 were from other states. The most typical gross lesions were widespread yellow adipose tissue and splenomegaly. Typical histopathological lesions included marked bile stasis and hemosiderin-laden macrophages in the liver and spleen, respectively. Starting in 2013, when PCR was implemented to confirm cases of anaplasmosis, 315/1125 (28%) were positive to A. marginale, and 810 were negative, using a cut-off of 35.0 Ct. The average (±SD) of the positive PCR Ct was 19.5 (±6.0), and the first and third quartiles were 14.9 and 23.4. Most cases occurred between August and November, peaking in September, whether from necropsies or positive blood samples by PCR. The most common tick observed in Iowa, Dermacentor variabilis, is likely the main vector for transmission. Further surveys should be conducted to estimate seroprevalence by geographical location, the density of cattle populations, distribution of known vectors according to season, and strains of A. marginale.

A recombinant porcine reproductive and respiratory syndrome virus type 2 field strain derived from two PRRSV-2-modified live virus vaccines.

A porcine reproductive and respiratory syndrome virus (PRRSV) type 2 (PRRSV-2) isolate was obtained from lung samples collected from a 4.5-month-old pig at a wean-to-finish site in Indiana, USA, although no gross or microscopic lesions suggestive of PRRSV infection were observed in the lung tissue. Phylogenetic and molecular evolutionary analyses based on the obtained virus sequences indicated that PRRSV USA/IN105404/2021 was a natural recombinant isolate from Ingelvac PRRS® MLV and Prevacent® PRRS, which are PRRSV-2-modified live virus vaccines commercially available in the United States. This study is the first to report the detection of a PRRSV-2 recombinant strain consisting entirely of two modified live virus vaccine strains under field conditions. Based on clinical data and the absence of lung lesions, this PRRSV-2 recombinant strain was not virulent in swine, although its pathogenicity needs to be confirmed by clinical trials.

Characterization of Two Porcine Parainfluenza Virus 1 Isolates and Human Parainfluenza Virus 1 Infection in Weaned Nursery Pigs.

Porcine parainfluenza virus 1 (PPIV1) is a newly characterized porcine respiratory virus. Recent experimental challenge studies in three-week-old nursery pigs failed to cause disease. However, it remains unclear how genetic differences contribute to viral pathogenesis. To characterize the pathogenesis of different PPIV1 isolates, three-week-old nursery pigs were challenged with either PPIV1 isolate USA/MN25890NS/2016 (MN16) or USA/IA84915LG/2017 (IA17). A human parainfluenza virus 1 (HPIV1) strain C35 ATCC® VR-94™ was included to evaluate swine as a model for human parainfluenza. All viruses were successfully re-isolated from bronchoalveolar lavage fluid and detected by RT-qPCR at necropsy. Microscopic lung lesions were more severe in the IA17 group compared to the non-challenged negative control (Ctrl) group whereas differences were not found between the MN16 and Ctrl groups. Immunohistochemistry staining in respiratory samples showed a consistent trend of higher levels of PPIV1 signal in the IA17 group followed by the MN16 group, and no PPIV1 signal observed in the HPIV1 or Ctrl groups. This study suggests potential pathogenesis differences between PPIV1 isolates. Additionally, these results indicate that HPIV1 is capable of replicating in nursery pigs after experimental inoculation. However, clinical disease or gross lung lesions were not observed in any of the challenge groups.

Bovine coronavirus in the lower respiratory tract of cattle with respiratory disease.

Bovine coronavirus (BCoV) is a known cause of enteric disease in cattle; however, its role in bovine respiratory disease (BRD) is poorly understood, with a dearth of evidence of the detection of the virus in respiratory tract lesions. We coupled histologic evaluation of tracheal and lower airway tissues from 104 calves with BRD in which BCoV was detected in the lungs via PCR followed by direct detection of BCoV by immunohistochemistry and an RNA in situ hybridization assay (ISH; RNAscope technology). RNAscope ISH detected BCoV in respiratory epithelium in more cases than did IHC. Using both methods of direct detection, tracheal epithelial attenuation and identification of the virus within lesions were observed commonly. Our results confirm a role of BCoV in respiratory tract infection and pathology, and show that the virus likely plays a role in the development of BRD.

Evaluation of the Efficacy of an S-INDEL PEDV Strain Administered to Pregnant Gilts against a Virulent Non-S-INDEL PEDV Challenge in Newborn Piglets.

A safe and efficacious live-attenuated vaccine for porcine epidemic diarrhea virus (PEDV) is not commercially available in the United States yet. Two major PEDV strains are currently circulating in US swine: highly virulent non-S-INDEL strain and milder virulent S-INDEL strain. In this study, the safety and protective efficacy of a plaque-purified S-INDEL PEDV isolate formulated as a vaccine candidate was evaluated. Ten pregnant gilts were divided into three groups and orally inoculated at 79 days of gestation and then boosted at 100 days gestation (T01: n = 4, vaccination/challenge; T02: n = 4, non-vaccination/challenge; T03: n = 2, non-vaccination/non-challenge). None of the gilts had adverse clinical signs after vaccination. Only one T01 gilt (#5026) had viral replication and detectible viral RNA in feces. The same gilt had consistent levels of PEDV-specific IgG and IgA antibodies in serum and colostrum/milk. Farrowed piglets at 3 to 5 days of age from T01 and T02 gilts were orally challenged with 103 TCID50/pig of the virulent non-S-INDEL PEDV while T03 piglets were orally inoculated with virus-negative medium. T01 litters had overall lower mortality than T02 (T01 36.4% vs. T02 74.4%). Specifically, there was 0% litter mortality from T01 gilt 5026. Overall, it appears that vaccination of pregnant gilts with S-INDEL PEDV can passively protect piglets if there is virus replication and immune response induction in the pregnant gilts.

Delivering an Immunocastration Vaccine via a Novel Subcutaneous Implant.

Immunocastration relies on the vaccine-mediated stimulation of an immune response to gonadotropin-releasing hormone (GnRH) in order to interrupt spermatogenesis. This approach offers a less painful alternative to traditional castration approaches but the current, commercially available options require multiple doses of vaccine to maintain sterility. Thus, a series of pilot studies were conducted to determine the feasibility of a single-dose immunocastration vaccine implant. These five studies utilized a total of 44 Holstein bulls to determine the optimal vaccine composition and validate the ability of a stainless-steel subcutaneous implant to deliver a vaccine. Outcome measures included the duration of implant retention, scrotal dimensions and temperature, implant site temperature, anti-GnRH antibodies, and serum testosterone concentration. Over the course of several studies, anti-GnRH antibodies were successfully stimulated by vaccine implants. No significant treatment effects on scrotal dimensions or testosterone were detected over time, but changes in spermatogenesis were detected across treatment groups. Results indicate that a single-dose implantable immunocastration vaccine elicits a humoral immune response and could impact spermatogenesis in bulls. These findings provide opportunities for the refinement of this technology to improve implant retention over longer periods of time. Taken together, this approach will offer producers and veterinarians an alternative to physical castration methods, to improve animal welfare during routine livestock management procedures.

Salmonella enterica serovar Brandenburg abortions in dairy cattle.

Two separate late-term abortion outbreaks in Jersey heifers in July 2020 and December 2020 were investigated by the Iowa State University Veterinary Diagnostic Laboratory. We evaluated 3 whole fetuses and 11 sets of fresh and formalin-fixed fetal tissues during the course of the outbreaks. The late-term abortions were first identified at a heifer development site and subsequently observed at the dairy farm. Aborted fetuses had moderate-to-marked postmortem autolysis with no gross lesions identified. Observed clinical signs in cows at the dairy farm ranged from intermittent loose stools to acute post-abortion pyrexia and reduced feed intake. Routine histopathology and reproductive bacterial culture revealed acute, suppurative placentitis with moderate-to-heavy growth of Salmonella spp. group B from stomach contents, liver, placenta, and heifer fecal contents. Serotyping identified Salmonella enterica subsp. enterica serovar Brandenburg in all 14 fresh tissue cases, as well as individual and pooled heifer feces. Whole-genome sequencing analysis revealed that all isolates belonged to ST type 873 and possessed typhoid toxin genes, several fimbrial gene clusters, type III secretion system genes, and several pathogenicity islands. Abortions caused by Salmonella Brandenburg have not been reported previously in dairy cattle in the United States, to our knowledge.

Ambient hydrogen sulfide exposure increases the severity of influenza A virus infection in swine.

Hydrogen sulfide (H2S) is common in concentrated pig feed operations from the decomposition of manure. Ambient H2S is a respiratory tract irritant and an environmental stressor for caretakers and pigs. Influenza A virus (IAV), a zoonotic pathogen, has caused prior pandemics. The effects of H2S or IAV alone on the respiratory system have been investigated, but their interaction has not. We hypothesized that exposure to environmentally-relevant H2S concentrations increases the pathogenicity of IAV infection in swine. Thirty-five, three-week old pigs of mixed sex were exposed to breathing air or H2S via inhalation 6 hours daily for 12 days. After 7 days, pigs were inoculated with H3N2 IAV (or a placebo). Results showed that ambient H2S increased the severity of respiratory distress and lung pathology. H2S also suppressed IL-IL-1ß, IL-6 and IL-8 cytokine response in BALF and increased viral loads and nasal shedding.

Comparative Analysis of Novel Strains of Porcine Astrovirus Type 3 in the USA.

Porcine astrovirus type 3 (PoAstV3) has been previously identified as a cause of polioencephalomyelitis in swine and continues to cause disease in the US swine industry. Herein, we describe the characterization of both untranslated regions, frameshifting signal, putative genome-linked virus protein (VPg) and conserved antigenic epitopes of several novel PoAstV3 genomes. Twenty complete coding sequences (CDS) were obtained from 32 diagnostic cases originating from 11 individual farms/systems sharing a nucleotide (amino acid) percent identity of 89.74-100% (94.79-100%), 91.9-100% (96.3-100%) and 90.71-100% (93.51-100%) for ORF1a, ORF1ab and ORF2, respectively. Our results indicate that the 5'UTR of PoAstV3 is highly conserved highlighting the importance of this region in translation initiation while their 3'UTR is moderately conserved among strains, presenting alternative configurations including multiple putative protein binding sites and pseudoknots. Moreover, two predicted conserved antigenic epitopes were identified matching the 3' termini of VP27 of PoAstV3 USA strains. These epitopes may aid in the design and development of vaccine components and diagnostic assays useful to control outbreaks of PoAstV3-associated CNS disease. In conclusion, this is the first analysis predicting the structure of important regulatory motifs of neurotropic mamastroviruses, which differ from those previously described in human astroviruses.

Distribution and persistence of atypical porcine pestivirus in experimentally inoculated pigs.

Atypical porcine pestivirus (APPV) is a cause of congenital tremors (CTs) in piglets and has been found in swine populations around the globe. Although systemic distribution of the virus has been reported, there is limited information regarding viral localization at the cellular level and distribution at the tissue level. We collected multiple tissues from 2-d-old piglets (n = 36) born to sows inoculated at 45 or 62 d of gestation with APPV via 3 simultaneous routes: intravenous, intranasal, and directly in amniotic vesicles. In addition, 2 boars from APPV-inoculated sows with CT were raised and euthanized when 11 mo old. In situ hybridization performed on tissue samples from piglets demonstrated a broad and systemic distribution of viral RNA including endothelial cells, fibroblasts, and smooth muscle. Labeling in tissues was more pronounced in piglet tissues compared to boars, with the notable exception of diffuse labeling of the cerebellum in boars. Presence of APPV in boar tissues well after resolution of clinical signs suggests persistence of APPV similar to other pestiviruses.

Effects of medium chain fatty acids as a mitigation or prevention strategy against porcine epidemic diarrhea virus in swine feed.

Feed has been shown to be a vector for viral transmission. Four experiments were conducted to: 1) determine if medium chain fatty acids (MCFA) are effective mitigants when applied to feed both pre- and post-porcine epidemic diarrhea virus (PEDV) inoculation measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR), 2) evaluate varying levels and combinations of MCFA measured by qRT-PCR, and 3) evaluate selected treatments in bioassay to determine infectivity. In exp. 1, treatments were arranged in a 2 × 2 + 1 factorial with main effects of treatment (0.3% commercial formaldehyde [CF] product, Sal CURB [Kemin Industries, Inc.; Des Moines, IA], or 1% MCFA blend (Blend) of 1:1:1 C6:C8:C10 [PMI, Arden Hills, MN]) and timing of application (pre- or post-inoculation with PEDV) plus a positive control (PC; feed inoculated with PEDV and no treatment). All combinations of treatment and timing decreased detectable PEDV compared with the PC (P < 0.05). Pre-inoculation treatment elicited decreased magnitude of PEDV detection (cycle threshold value) compared with post-inoculation (P = 0.009). Magnitude of PEDV detection was decreased for CF compared with Blend (P < 0.0001). In exp. 2, pre-inoculation treatments consisted of: 1) PC, 2) 0.3% CF, 3 to 5) 0.125% to 0.33% C6:0, 6 to 8) 0.125% to 0.33% C8:0, 9 to 11) 0.125% to 0.33% C10:0, and 12 to 15) 0.125% to 0.66% C5:0. Treating feed with 0.33% C8:0 resulted in decreased (P < 0.05) PEDV detection compared with all other treatments. Increasing concentration of each individual MCFA decreased PEDV detectability (P < 0.042). In exp. 3, pre-inoculation treatments consisted of: 1) PC, 2) 0.3% CF, 3 to 7) 0.25% to 1% Blend, 8 to 10) 0.125% to 0.33% C6:0 + C8:0, 11 to 13) 0.125% to 0.33% C6:0 + C10:0, and 14 to 16) 0.125% to 0.33% C8:0 + C10:0. Treating feed with CF, 0.5% Blend, 0.75% Blend, 1% Blend, all levels of C6:0+C8:0, 0.25% C6:0 + 0.25% C10:0, 0.33% C6:0 + 0.33% C10:0, 0.25% C8:0 + 0.25% C10:0, or 0.33% C8:0 + 0.33% C10:0 elicited decreased detection of PEDV compared with PC (P < 0.05). Increasing concentration of each MCFA combination decreased PEDV detectability (linear, P < 0.012). In exp. 4, feed was treated pre-inoculation with: 1) no treatment (PC), 2) 0.3% CF, 3) 0.5% Blend, or 4) 0.3% C8:0 and analyzed via qRT-PCR and bioassay. Adding 0.5% Blend or 0.3% C8:0 resulted in decreased PEDV compared with PC and only PC resulted in a positive bioassay. Therefore, MCFA can decrease detection of PEDV in feed. Further, inclusion of lower levels of MCFA than previously evaluated are effective against PEDV.