Isolation and Phylogenetic Analysis of Reemerging Pseudorabies Virus Within Pig Populations in Central China During 2012 to 2019

To understand the biological characteristics of the reemerging pseudorabies virus (PRV) strains, a total of 392 tissue samples were collected from diseased pigs during reemerging PR outbreaks between 2012 and 2019 on farms in central China where swine had been immunized with Bartha-K61 and 51 (13. 01%) were positive for the gE gene by PCR. Sixteen PRV strains were isolated and caused clinical symptoms and death in mice. Subsequently, gE, gC, gB, and gD complete genes were amplified from the 16 PRV isolates and sequenced. Phylogenetic analysis based on these four gene sequences shows that the 16 PRV isolates were more closely related to the Chinese PRV variants (after 2012) but genetically differed from early Chinese PRV isolates (before 2012). Sequence analysis reveals that PRV isolates exhibited amino acid insertions, substitutions, or deletions compared with early Chinese PRV isolates and European–American PRV strains. In addition, this is the first report that eight isolates (8/16) in this study harbor a unique amino acid substitution at position 280 (F to L) of the gC protein, and six isolates have an amino acid substitution at position 338 (A to V) of the gD protein compared with the Chinese PRV variants. The emulsion containing inactivated PRV NY isolate could provide complete protection against the NY isolate. This study might enrich our understanding of the evolution of reemerging PRV strains as well as pave the way for finding a model virus to develop a novel vaccine based on reemerging PRV strains.

Single Nucleotide Polymorphisms in Bmy1 Intron III Alleles Conferring the Genotypic Variation in β-amylase Activity under Drought Stress Between Tibetan Wild and Cultivated Barley

β-amylase activity is related to the polymorphism of Bmy1 intron III; however, no attention has been given to such relationship under environmental stresses like drought. In this study, 73 cultivated barley genotypes and 52 Tibetan wild barley accessions were used to test the association between Bmy1 gene intron III polymorphisms and β-amylase activity under drought stress. Our results showed that three alleles, Bmy1.a, Bmy1.b and Bmy1.c, existed in the examined barley genotypes. Tibetan wild barley had higher proportion of Bmy1.b, whereas cultivated barley showed higher proportion of Bmy1.a. Impressively, barley genotypes with Bmy1.b showed significant increase in β-amylase activity under drought stress, compared with those with Bmy1.a or Bmy1.c, indicating that Bmy1.b allele might provide more chances for developing barley cultivars with higher β-amylase activity under water stress than both Bmy1.a and Bmy1.c alleles. Furthermore, the Tibetan wild barley XZ147, belonging to Bmy1.b allele type, showed significant higher β-amylase activity than the cultivar Triumph under drought stress. This might result from the unique amino acid substitution M527 or the amino acid composition of R115, D165, A233, S347 and M527 of XZ147.

Genetic Analyses of Penicillin Binding Protein Determinants in Multidrug-Resistant Streptococcus pneumoniae Serogroup 19 CC320/271 Clone with High-Level Resistance to Third-Generation Cephalosporins

ABSTRACTWe describe the dissemination of a multidrug-resistant (MDR) serogroup 19 pneumococcal clone of representative multilocus sequence type 271 (ST271) with high-level resistance to cefotaxime in Hong Kong and penicillin binding protein (pbp) genes and its relationships to Taiwan19F-14 and the prevalent multidrug-resistant 19A clone (MDR19A-ST320). A total of 472 nonduplicate isolates from 2006 and 2011 were analyzed. Significant increases in the rates of nonsusceptibility to penicillin (PEN) (MIC ≥ 4.0 μg/ml; 9.9 versus 23.3%;P= 0.0005), cefotaxime (CTX) (MIC ≥ 2.0 μg/ml; 12.2 versus 30.3%;P< 0.0001 [meningitis MIC ≥ 1.0 μg/ml; 30.2 versus 48.7%;P= 0.0001]), and erythromycin (ERY) (69.2 versus 84.0%;P= 0.0003) were noted when rates from 2006 and 2011 were compared. The CTX-resistant isolates with MICs of 8 μg/ml in 2011 were of serotype 19F, belonging to ST271. Analyses of the penicillin binding protein 2x (PBP2x) amino acid sequences in relation to the corresponding sequences of the R6 strain revealed M339F, E378A, M400T, and Y595F substitutions found within the ST271 clone but not present in Taiwan19F-14 or MDR19A. In addition, PBP2bs of ST271 strains and that of the Taiwan19F-14 clone were characterized by a unique amino acid substitution, E369D, while ST320 possessed the unique amino acid substitution K366N, as does that of MDR19A in the United States. We hypothesize that ST271 originated from the Taiwan19F-14 lineage, which had disseminated in Hong Kong in the early 2000s, and conferred higher-level β-lactam and cefotaxime resistance through acquisitions of 19 additional amino acid substitutions in PBP2b (amino acid [aa] positions 538 to 641) and altered PBP2x via recombination events. The serogroup 19 MDR CC320/271 clone warrants close monitoring to evaluate its effect after the switch to expanded conjugate vaccines.

Herbicide Cross-Resistance and Mutations of the psbA Gene in Chlamydomonas reinhardtii

The resistance against herbicides (inhibitors of the electron accepting side) of photosystem II originates from mutations of the psb A gene, coding for the D 1 or QB binding protein. Each of the five mutants used in the present study had single base changes in the psbA gene that resulted in a unique amino acid substitution at a different residue of the D1 protein (Val-219, Ala-251, Phe-255, Ser-264, Leu-275). The differences of the I50-values in the electron transfer reaction of H2O to dichlorophenolindophenol were used to analyze the correlation of these amino acid residue changes to their impact on the binding of diverse chemical classes of inhibitors. The binding domains on the D1 protein of the inhibitors overlap, but are nevertheless distinct. Even minor changes in the chemical structure of the inhibitors resulted in changes of the resistance toward a specific amino acid residue. A pattern of response of the inhibitors to the amino acid substitutions evolves that allows easy differentiation between the groups of PS II inhibitors. Two principally different response curves emerge for two different families of PS II inhibitors, that had been proposed earlier already on functional studies with wild types. But the response pattern of newly described inhibitors, like ketonitrile and quinolone derivatives, in the mutants allows to group them with confidence and in turn generalize the phenol type family. In none of the five mutants, studied here, is there a marked cross-resistance to the new phenol type inhibitors. Just the opposite, in several cases, there is negative cross-resistance (or supersensitivity). Because of this response pattern this group of inhibitors cannot be oriented with certainty in the three dimensional folding model of the D1 protein.