Genetic analysis of NS5B gene from bovine viral diarrhea virus-infected cattle in Central and East Java, Indonesia.

BACKGROUND AND AIM: A previous study divided Indonesian bovine viral diarrhea virus (BVDV)-1 into subgenotypes BVDV-1a to BVDV-1d based on the partial NS5B gene using strain Bega as reference for BVDV-1a. In fact, it is clustered into BVDV-1c with strain Bega-like Australia. BVDV genotyping has been done on isolates from Jakarta, West and Central Java, but East Java isolates have not been genotyped. This study aimed to analyze genetic variability and amino acid residues in the nucleotide-binding pocket of the NS5B gene from infected cattle. MATERIALS AND METHODS: Samples were obtained from the Sera Bank originating from active and passive surveillance of cattle that had been tested for BVDV antigen from 2013 to 2017. Detection of the p80 antibody and BVDV genotyping was carried out using ELISA and nested-multiplex-polymerase chain reaction (PCR), respectively. We defined 15 nested PCR products for partial sequencing of NS5B. Those field samples were selected from each location and year using proportional calculation as a representative sample. Homological and phylogenetic analyses of the partial NS5B gene were performed using BLAST and MEGA version 6. RESULTS: Based on the phylogenetic tree analysis using 360 nucleotides as the partial NS5B gene, Indonesian BVDV-1 isolates from Central and East Java were subdivided to BVDV-1a (n=9), BVDV-1b (n=1), and BVDV-1c (n=5). In the present study, the homology of BVDV subgenotype -1a, -1b, and -1c was compared to the BVDV GenBank data and found 90-93%, 93%, and 92-95% respectively with the average pairwise distance of 0.207. A point mutation was shown at R283K of all BVDV isolates based on the sequence of three amino acid residues R283, R285, and I287 in the nucleotide-binding pocket as a part of the encoded RNA-dependent RNA polymerase. CONCLUSION: This study revealed the genetic variability of BVDV infecting cattle in Central Java and East Java, Indonesia, the subtypes BVDV-1a, BVDV-1b, BVDV-1c, and a point mutation at the R283K residue.

Phagocytic uptake and killing of virulent and avirulent strains of Pasteurella multocida of capsular serotype A by chicken macrophages.

The susceptibility of two highly virulent (VP161 and VP138) and two less virulent (VP17 and VP21) strains of Pasteurella multocida to phagocytic uptake and killing by chicken macrophages was compared using in vitro phagocytosis and bactericidal assays. When compared with VP17 and VP21, particularly after they were preopsonised with specific immune serum, VP161 and VP138 were more resistant to phagocytosis by chicken macrophages. The uptake of these bacteria increased following the removal of the bacterial capsules with hyaluronidase. All strains preopsonised with specific immune serum were killed to some extent by chicken macrophages. However, the percentages of killing for VP17 and VP21 were higher than those of VP161 and VP138. When the capsules of VP161 and VP138 were removed, the susceptibility of the bacteria to bactericidal activity of chicken macrophages increased. It can be concluded that the virulent strains of P. multocida were more resistant to phagocytosis and phagocytic killing by chicken macrophages compared with the less virulent strains. The hyaluronic acid capsule was considered to be important in the resistance, but might not be the only factor contributing to the resistance since the less virulent strains of P. multocida also possess capsules.

Cellular responses in experimental chronic and acute dermatophilosis infections of sheep.

The cellular infiltrate into the dermis in dermatophilosis lesions is composed of a range of cell types. The aim of this study was to establish if the composition of the cellular infiltrate in chronic lesions was different from that in healing lesions. Experimental Dermatophilus congolensis infections of sheep were used to study the sequential changes in cell types during the course of chronic and acute infections. Infestations of adult Amblyomma variegatum ticks were used to produce chronic lesions on infected sheep, infections of tick-free sheep provided acute lesions. Histopathology and immunohistochemistry were used to stain and label cell types in the dermis of infection sites. Neutrophils dominated the early response and were present in larger numbers in chronic lesions. Plasma cells were present in both types of lesion, however they persisted in chronic lesions but disappeared from the skin at acute lesion sites after the lesions had resolved. There were 2-3 times as many mononuclear cells in chronic than acute lesions from as early as 4 days post infection and these cells persisted in the chronic lesions. In the chronic lesions the mononuclear cell population was composed of T-helper and T-cytotoxic/suppressor lymphocytes in equal proportions whereas in acute lesions at 14 days post infection, when lesion resolution is underway, there were greater numbers of T-helper cells than T-cytotoxic/suppressor cells.