ABSTRACT
Porcine circovirus type 2 (PCV2), the causative agent of porcine circovirus-associated diseases (PCVADs), has a worldwide distribution, and is considered as one of the most important emerging viral pathogens of economic importance. In Kerala, a total of 62 tissue samples were collected during post mortem from pigs suspected to have died of PCV2 infection. The animals exhibited symptoms like respiratory illness, gradual wasting, rough hair coat, polypnoea, dyspnoea, pallor, diarrhoea, icterus, etc. PCV2 was detected in 36 (58.06%) samples by PCR. Phylogenetic analyses of complete ORF2, and complete genome sequences were carried out and genotypes 2d, 2 h and 2b were detected. The genotype predominant in Kerala was 2d. It was observed that genotypes 2 h and 2b have been recently introduced into North Kerala as it was not detected in the region prior to 2016. Close relationship of Kerala sequences with sequences from Tamil Nadu, Uttar Pradesh and Mizoram were noticed in the phylogenetic tree and also at the amino acid level. A unique K243N mutation was observed in one of the samples. It was also noticed that the most variable amino acid position in ORF2 was 169 where the occurrence of three possible amino acids were observed. The results of the study indicate that multiple genotypes of PCV2 are prevalent in pigs in Kerala and that the percent positivity is higher than that recorded in the State previously. Supplementary Information: The online version contains supplementary material available at 10.1007/s13337-023-00814-1.
ABSTRACT
The ultrasonic attenuation and backscatter coefficients of tissues are relevant acoustic parameters due to their wide range of clinical applications. In this paper, a linear least-squares method for the estimation of these coefficients in a homogeneous region of interest based on pulse-echo measurements is proposed. The method efficiently fits an ultrasound backscattered signal model to the measurements in both the frequency and depth dimension simultaneously at a low computational cost. It is demonstrated that the inclusion of depth information has a positive effect particularly on the accuracy of the estimated attenuation. The sensitivity of the attenuation and backscatter coefficients' estimates to several predefined parameters such as the window length, window overlap and usable bandwidth of the spectrum is also studied. Comparison of the proposed method with a benchmark approach based on dynamic programming highlights better performance of our method in estimating these coefficients, both in terms of accuracy and computation time. Further analysis of the computation time as a function of the predefined parameters indicates our method's potential to be used in real-time clinical settings.
