Effects of Compound Trace Minerals on the Growth Performance, Carcass Characteristics and Meat Quality of Fattening Pigs.

The objective of this study was to evaluate the effects of supplemental levels of compound minerals (CM), which was formulated from a mixture of 300 mg calcium, 150 mg magnesium, 25 mg zinc, 15 mg iron, 4 mg manganese, and 2 mg copper per gram, on the growth performance and feed conversion ratio of Duroc × (Landrace × Yorkshire) fattening pigs. A total of 53 female pigs and 45 male pigs at 35 days of age were individually notched and randomly allocated to three treatments, including0 (basal diet), 0.5 (basal diet with 0.5 mg CM/kg feed), and 1 (basal diet with 1 mg CM/kg feed). There were three replicates for each of the three treatments with 28, 34, and 36 pigs in the first, second, and third treatments, respectively. The experiment was divided into two phases, the growing stage, and the finishing stage. Supplementation of compound minerals in the diet led to an increased average daily weight gain and improved feed conversion ratio and meat quality without effects on the lean meat percentage. An addition of 1 mg of compound minerals per 1 kg of feed is the recommended dose to improve the production performance of fattening pigs. These results suggest that the use of compound minerals could improve the growth traits of fattening pigs under tropical environmental conditions.

O/SEA/Mya-98 lineage foot-and-mouth disease virus was responsible for an extensive epidemic that occurred in late 2018 in Vietnam.

Since late 2018, foot-and-mouth disease (FMD) has reemerged and rapidly swept through pig farms in North and Central Vietnam, despite widespread use of commercial FMD vaccines. To investigate the FMD virus (FMDV) strains responsible for the current epidemics, 40 FMDV samples were collected from 17 provinces during November-December 2018, and the VP1 coding genes were sequenced and analyzed. Phylogenetic analysis and sequence comparisons revealed that all of the reemerging Vietnamese FMDVs belonged to the Mya-98 lineage of the O/Southeast Asia topotype (O/SEA/Mya-98) and shared high nucleotide (99.06-100% identity) and amino acid (97.65-100% identity) sequence similarity with each other. The study results suggested that the reemerging FMDVs originated from local Vietnamese strains. Field viruses had different amino acids in the antigenic sites of VP1 when compared to the strains used in the vaccines. The present study provides an important basis for vaccine selection in the battle against FMD in Vietnam.

Distribution of infectious endogenous retroviruses in mixed-breed and purebred cats.

Endogenous retroviruses of domestic cats (ERV-DCs) are members of the genus Gammaretrovirus that infect domestic cats (Felis silvestris catus). Uniquely, domestic cats harbor replication-competent proviruses such as ERV-DC10 (ERV-DC18) and ERV-DC14 (xenotropic and nonecotropic viruses, respectively). The purpose of this study was to assess invasion by two distinct infectious ERV-DCs, ERV-DC10 and ERV-DC14, in domestic cats. Of a total sample of 1646 cats, 568 animals (34.5%) were positive for ERV-DC10 (heterozygous: 377; homozygous: 191), 68 animals (4.1%) were positive for ERV-DC14 (heterozygous: 67; homozygous: 1), and 10 animals (0.6%) were positive for both ERV-DC10 and ERV-DC14. ERV-DC10 and ERV-DC14 were detected in domestic cats in Japan as well as in Tanzania, Sri Lanka, Vietnam, South Korea and Spain. Breeding cats, including Singapura, Norwegian Forest and Ragdoll cats, showed high frequencies of ERV-DC10 (60-100%). By contrast, ERV-DC14 was detected at low frequency in breeding cats. Our results suggest that ERV-DC10 is widely distributed while ERV-DC14 is maintained in a minor population of cats. Thus, ERV-DC10 and ERV-DC14 have invaded cat populations independently.

Molecular epidemiology of canine parvovirus type 2 in Vietnam from November 2016 to February 2018.

BACKGROUND: Canine parvovirus type 2 (CPV-2) was first identified in the late 1970s; it causes intestinal hemorrhage with severe bloody diarrhea in kennels and dog shelters worldwide. Since its emergence, CPV-2 has been replaced with new genetic variants (CPV-2a, CPV-2b, and CPV-2c). Currently, information about the genotype prevalence of CPV-2 in Vietnam is limited. In the present study, we investigated the genotype prevalence and distribution of CPV-2 in the three regions of Vietnam. METHODS: Rectal swabs were collected from 260 dogs with suspected CPV-2 infection from northern, central, and southern Vietnam from November 2016 to February 2018. All samples were identified as parvovirus positive by real-time PCR, and further genotyping was performed using a SimpleProbe® real-time PCR assay. RESULTS: Of the 260 Vietnamese CPV-2 isolates, 6 isolates (2.31%) were identified as CPV-2a, 251 isolates (96.54%) were identified as CPV-2c and 3 isolates (1.15%) were untypable using the SimpleProbe® real-time PCR assay. In northern Vietnam, the percentages of CPV-2a and CPV-2c were 2.97% (3/101) and 97.3% (98/101), respectively. In central Vietnam, the percentages of CPV-2a and CPV-2c were 1.11% (1/90) and 98.89% (89/90), respectively. In southern Vietnam, the percentages of CPV-2a and CPV-2c were 3.03% (2/66) and 96.97% (64/66), respectively. CPV-2b was not observed in this study. The VP2 genes of CPV-2c in Vietnam are more genetically similar to those of CPV-2c strains in China and Taiwan than to those of prototype CPV-2c strains (FJ222821) or the first Vietnamese CPV-2c (AB120727). CONCLUSION: The present study provides evidence that CPV-2c is the most prevalent variant in Vietnam. Phylogenetic analysis demonstrated that the recent Vietnamese CPV-2c isolates share a common evolutionary origin with Asian CPV-2c strains.

Genetic characterization of bovine coronavirus in Vietnam.

A maximum clade credibility tree constructed using the full-length spike (S) and hemagglutinin-esterase genes revealed that Vietnamese Bovine coronavirus (BCoV) strains belong to a single cluster (C1); therefore, they might share a common origin with Cuban and Chinese BCoV strains. The omega values of cluster 1 (C1) and cluster 2 (C2) were 0.15734 and 0.11613, respectively, and naive empirical bayes analysis identified two amino acid positions (179 and 501) in the S protein in C1 and three amino acid positions (113, 501, and 525) in that of C2 that underwent positive selection (p > 99%). The evolutionary rate of C1 was estimated to be 7.6206 × 10-4 substitutions/site/year, and the most recent common ancestor (tMRCA) of Vietnamese BCoVs was estimated to date back to 1962 (95% HPD 1950-1973). The effective population sizes of C1 and C2 underwent a rapid reduction after 2000 and 2004, respectively.

Identification and characterization of the interactive proteins with cytotoxic T-lymphocyte antigen-2α.

Cytotoxic T-lymphocyte antigen-2α (CTLA-2α) is a potent inhibitor of cathepsin L-like cysteine proteases. Recombinant CTLA-2α is known to be a potent, competitive inhibitor of cathepsin L-like cysteine proteases. In this study, cathepsin L, cathepsin C, and tubulointerstitial nephritis antigen-related protein 1 (TINAGL1) were identified as novel interactive proteins of CTLA-2α by the yeast two-hybrid screening system. The direct interactions and co-localization of these proteins with CTLA-2α were confirmed using co-immunoprecipitation and immunofluorescence staining, respectively. The disulfide-bonded CTLA-2α/cathepsin L complex was isolated from mouse tissue. CTLA-2α was found to be specific and consistently expressed on the maternal side of the mouse placenta. Double immunofluorescence analysis showed that CTLA-2α was co-localized with cathepsin L, cathepsin C, and TINAGL1 in placenta. A simple cell-based fluorescence assay revealed that CTLA-2α exhibited inhibitory activity toward cathepsin C in live cells, which indicated that CTLA-2α is a novel endogenous inhibitor of cathepsin C.

Evaluation of Selective Culling as a Containment Strategy for African Swine Fever at a Vietnamese Sow Farm.

Selective culling, also known as the "tooth extraction approach", is a strategy for controlling African swine fever (ASF) by removing only sick and suspect animals instead of the entire herd in Vietnam. This method prioritizes preserving healthy animals, particularly valuable breeding pigs. Despite its implementation in various forms, no standardized protocol based on scientific principles has been established. Farms typically adapt this strategy based on their understanding, which can vary significantly. In implementing of selective culling that is not based on scientific principles, there is a significant risk of spreading the disease. The aim of this study is to evaluate the consequences of selective culling as currently implemented in Vietnam. Our analysis on a large sow farm revealed that current practices rely heavily on clinical observations without laboratory confirmations. This approach allows ASF-infected animals to remain on the farm longer, potentially exacerbating the spread of the virus. Thus, selective culling poses a substantial risk by potentially exacerbating the spread of disease. Our findings emphasize that early diagnosis of ASF and systematic removal of infected pigs are critical components for the effective implementation of selective culling strategies and that a high level of fragmentation to minimize contact between animals plays a key role. The optimal approach is to test conspicuous animals and separate them. Under no circumstances should suspect animals be left in the herd for several days before they become severely ill and succumb to the disease.

Implications of partial culling on African swine fever control effectiveness in Vietnam.

The introduction of the African swine fever (ASF) into previously unaffected countries often overwhelms veterinary authorities with the resource demanding control efforts that need to be undertaken. The approach of implementing total stamping out of affected herds is taken as "default" control measure in many countries, regardless of the transboundary animal disease addressed, leading to a variety of challenges when implemented. Apart from the organizational challenges and high demand for human and financial resources, the total stamping out approach puts a high burden on the livelihoods of the affected farmers. After the spread of ASF throughout the country in 2019, Vietnam changed the culling approach enabling partial culling of only affected animals in the herd, in order to save resources, and reduce the environmental impact because of the carcass disposal and allow farmers to protect valuable assets. Until now, field data comparing these disease control options in their performance during implementation has not been evaluated scientifically. Analyzing the effect of the change in a control policy, the present study concludes that partial culling can on average save over 50% of total stock with an 8-day prolongation of the implementation of control measures. With 58% of farms undergoing partial culling scoring high on a time-livelihoods matrix, while total stamping out fails to score on livelihoods, much-needed clarity on the livelihood-protecting effects of alternative culling strategies is given. In the future, this will allow veterinary authorities to adjust control measures according to differing priorities, targeting peculiarities of ASF and acknowledging resource constraints faced.

Blood parameters and pathological lesions in pigs experimentally infected with Vietnam's first isolated African swine fever virus.

African swine fever virus (ASFV) is a notable virus and one of the most serious global threats to the pig industry. Improving awareness about host-virus interactions could facilitate the understanding of the disease pathogenesis. Therefore, we investigated changes in blood parameters, viral loads, and pathological changes in ASFV-inoculated pigs according to the time of death after the onset of viremia. For the analyses, the ASFV-infected pigs (n = 10) were divided into two groups (five pigs/group) according to their time of death after the onset of viremia. The blood cell count dynamics and serum biochemistry profiles were similar between the groups; however, viral load distribution was different. A comparison of the histopathological changes and immunohistochemistry results between the two groups indicated that the lymphoid system, particularly the spleen, was more damaged in the early stage of the disease than in the last stage. Additionally, the virus-induced lesions in other organs (liver and kidney) were more severe in the late stage than in the early stage. Our findings provide invaluable information on the characteristics of blood parameters and pathological lesions in pigs infected with the Asia-epidemic ASFV strain and the course of ASF, targeting internal organs in pigs. Overall, this study characterizes the host-pathogen interaction in ASFV infection, offering insight for the establishment of ASF control strategies.

Rapid and highly sensitive portable detection of African swine fever virus.

African swine fever (ASF) continues to spread across Asia, devastating pig populations. The disease is nearly 100% fatal in pigs, and currently, there is no effective vaccine available. Therefore, early detection of ASF is critical for effective disease control. The testing process usually requires samples to be shipped to a central laboratory, which may take many hours of travel or shipping time, delaying the results needed for a rapid response. The ability to confirm ASFV-infected animals on-site or in a regional laboratory that has limited technical capacity and/or infrastructure should eliminate these issues. This study describes the successful transfer of a highly sensitive and specific laboratory-validated real-time PCR assay to a portable pen-side thermocycler, which can be operated in the field for rapid detection of ASFV following a quick manual nucleic acid extraction from a wide array of clinical samples including aggregate samples such as oral fluids. The performance of the portable assay was comparable to the laboratory-based assay. The true portability of the assay was evaluated in seven ASF-suspected farms in Vietnam by testing eighty-nine freshly collected whole blood samples on-site. The results obtained on-site were in agreement with the laboratory data obtained the following day. Availability of this field-deployable molecular assay would eliminate the need to ship samples to a central laboratory, when rapid laboratory results are required, ultimately improving the response time.

Clinical and Pathological Study of the First Outbreak Cases of African Swine Fever in Vietnam, 2019.

African swine fever (ASF) is a devastating disease of swine and the most important disease for the pork industry. Since the outbreaks in 2007 in the Caucasian region, it has been spreading to the West and East quite swiftly. In this study we have analyzed the clinical signs and pathological features of the first outbreaks on ASF in Vietnam in 2019, caused by an isolate with 100% similarity to the genotype II (p72) isolates from Georgia in 2007 and China in 2018. The disease onset with a peracute to acute clinical course with high mortality. Some animals showed very unspecific clinical signs with other showing severe hyperthermia, respiratory distress, diarrhea, or vomit. Hemorrhagic splenomegaly and lymphadenitis were the main lesions observed at post mortem examination, with histopathological changes confirming the lymphoid depletion and multiorganic hemorrhages. Monocyte-macrophages were identified by means of immunohistochemical methods as the main target cell for the ASF virus in tissue sections.

Cathepsin L coexists with Cytotoxic T-lymphocyte Antigen-2 alpha in distinct regions of the mouse brain.

Cathepsins B and L are two prominent members of cystein proteases with broad substrate specificity and are known to be involved in the process of intra- and extra-cellular protein degradation and turnover. The propeptide region of cathepsin L is identical to Cytotoxic T-lymphocyte antigen-2α (CTLA-2α) discovered in mouse activated T-cells and mast cells. CTLA-2α exhibits selective inhibitory activities against papain and cathepsin L. We previously demonstrated the distribution pattern of the CTLA-2α protein in mouse brain by immunohistochemistry, describing that it is preferentially localized within nerve fibre bundles than neuronal cell bodies. In the present study we report colocalization of cathepsin L and CTLA-2α by double labeling immunofluorescence analysis in the mouse brain. In the telencephalon, immunoreactivity was identified in cerebral cortex and subcortical structures, hippocampus and amygdala. Within the diencephalon intense colocalization was detected in stria medullaris of thalamus, mammillothalamic tract, medial habenular nucleus and choroid plexus. Colocalization signals in the mesencephalon were strong in the hypothalamus within supramammillary nucleus and lateroanterior hypothalamic nucleus while in the cerebellum was in the deep white matter, granule cell layer and Purkinje neurons but moderately in stellate, and basket cells of cerebellar cortex. The distribution pattern indicates that the fine equilibrium between synthesis and secretion of cathespin L and CTLA-2α is part of the brain processes to maintain normal growth and development. The functional implication of cathespin L coexistence with CTLA-2α in relation to learning, memory and disease mechanisms is discussed.