Applicability of Raman spectroscopy on porcine parvovirus and porcine circovirus type 2 detection

Porcine parvovirus (PPV) is one of the major infectious causes of reproductive failure of swine. This disease is characterized by embryonic and fetal infection and death, responsible for important economic losses. PPV is also implicated as a trigger in the development of post-weaning multisystemic wasting syndrome (PMWS) caused by Porcine circovirus type 2 (PCV2). Their detection is PCR-based, which is quite sensitive and specific, but laborious, costly and time-demanding. Therefore, this study aimed to assess Raman spectroscopy (RS) as a diagnostic tool for PPV and PCV2 due to its label-free properties and unique ability to search and identify molecular fingerprints. Briefly, swine testis (ST) cells were inoculated with PPV or PCV2 and in vitro cultured (37 °C, 5% CO₂) for four days. Fixed cells were then submitted to RS investigation using a 633 nm laser. A total of 225 spectra centered at 1300 cm^-1 was obtained for each sample (5 spectra/cell; 15 cells/replicate; 3 replicates) of PPV-, PCV2-infected and uninfected (control) ST cells. Clear statistical discrimination between samples from both virus-infected cells was achieved with a Principal Component - Linear Discriminant Analysis (PCA-LDA) model, reaching sensitivity rates from 95.55% to 97.77%, respectively to PCV2- and PPV-infected cells. These results were then submitted to a Leave-One-Out (LOO) validation algorithm resulting in 99.97% of accuracy. Extensive band assignment was analyzed and compiled for better understanding of PPV and PCV2 virus-cell interaction, demonstrating that specific protein, lipids and DNA/RNA bands are the most important assignments related to discrimination of virus-infected from uninfected cells. In conclusion, these results represent promising bases for RS application on PCV2 and PPV detection for future diagnostic applications.

Histopathological Findings in the Viscera of Malformed Neotropical Viperids

Congenital malformations (CMs) or developmental abnormalities are pathological processes defined as morphological defects that originate during embryonic stages. A wide variety of CMs is observed in reptiles, most of which are incompatible with normal life. Characterization of CMs and their pathogenesis are of great importance for the conservation of reptiles, including neotropical viperids (NVs). External CMs are often reported in these species, but little is known about concomitant microscopical findings in the viscera of malformed individuals. In order to partially fill in this gap in knowledge, we aimed to investigate and characterize histopathological findings in the viscera of malformed NVs, jararacas (Bothrops jararaca) and South American rattlesnakes (Crotalus durissus), correlating these findings with features of external CMs. From 78 malformed snakes analysed, 100% (19/19) of rattlesnakes and 98.3% (58/59) of jararacas had histopathological changes in the viscera. Liver and/or kidney fatty degeneration was the most common finding in malformed and control animals. Renal glomerulocystic and tubular disease was significantly correlated with brachygnathia (P < 0.05) in jararacas. These results add to the body of knowledge of snake pathology and demonstrate some associations between external CMs and visceral histopathological findings, some of which could have implications for individual survival.