Several coronaviruses (CoVs) have been identified as human pathogens, including the α-CoVs strains HCoV-229E and HCoV-NL63 and the β-CoVs strains HCoV-HKU1 and HCoV-OC43. SARS-CoV, MERS-CoV, and SARS-CoV-2 are also classified as β-coronavirus. New SARS-CoV-2 spike genomic variants are responsible for human-to-human and interspecies transmissibility, consequences of adaptations of strains from animals to humans. The receptor-binding domain (RBD) of SARS-CoV-2 binds to receptor ACE2 in humans and animal species with high affinity, suggesting there have been adaptive genomic variants. New genomic variants including the incorporation, replacement, or deletion of the amino acids at a variety of positions in the S protein have been documented and are associated with the emergence of new strains adapted to different hosts. Interactions between mutated residues and RBD have been demonstrated by structural modelling of variants including D614G, B.1.1.7, B1.351, P.1, P2; other genomic variants allow escape from antibodies generated by vaccines. Epidemiological and molecular tools are being used for real-time tracking of pathogen evolution and particularly new SARS-CoV-2 variants. COVID-19 vaccines obtained from classical and next-generation vaccine production platforms have entered clinicals trials. Biotechnology strategies of the first generation (attenuated and inactivated virus–CoronaVac, CoVaxin; BBIBP-CorV), second generation (replicating-incompetent vector vaccines–ChAdOx-1; Ad5-nCoV; Sputnik V; JNJ-78436735 vaccine-replicating-competent vector, protein subunits, virus-like particles–NVX-CoV2373 vaccine), and third generation (nucleic-acid vaccines–INO-4800 (DNA); mRNA-1273 and BNT 162b (RNA vaccines) have been used. Additionally, dendritic cells (LV-SMENP-DC) and artificial antigen-presenting (aAPC) cells modified with lentiviral vector have also been developed to inhibit viral activity. Recombinant vaccines against COVID-19 are continuously being applied, and new clinical trials have been tested by interchangeability studies of viral vaccines developed by classical and next-generation platforms.

Chromosomal abnormalities or aberrations were investigated in ten bovines, three canines and three equines presenting cutaneous papillomatosis. The aim of the present study was to evaluate possible chromosomal abnormalities as a biomarker of genomic instability induced by the interaction of the viral genome with the chromatin of the host cell in peripheral blood lymphocytes and skin warts lesion cultures. Genomic DNA was extracted from blood samples and epithelial biopsies. Amplification products from PCR using degenerated primer pair FAP59/FAP64 were sequenced. Peripheral blood lymphocytes and tumor cell cultures were performed. Structural chromosomal aberrations were verified as associations, chromosomal fragments, centric fusions, open chromatids, gaps, rearrangements and rings. Several levels of premature chromosome condensation were observed in both cultures. Numeric abnormalities as aneuploidy were also detected and hipoployd cells were found in a larger number than the hiperployd cells. This cytogenetic study in detecting premature chromosome condensation in the three species investigated describes by the first time the structural and numerical abnormalities in canines and equines presenting papillomatosis lesions. These abnormalities are similar of the three groups of animals, but virus specific.

Computer modeling is an area of broad multidisciplinary knowledge that includes the study of various biological systems. This chapter will describe the molecular aspects of viral infections and molecular modeling techniques applied to drug discovery with examples of applications in protein activity inhibition in several pathologies. The first part will cover topics of computational chemistry methods, DNA technologies, structural modeling of virus proteins, molecular biology, viral vectors, virus-like particles, and pharmaceutical bioprocess with application in some specific viruses such as papillomavirus, hepatitis B virus, hepatitis C virus, Coronavirus, and Zika Virus. The second part will deal with methods in Virtual Screening for the drug design based on ligands and on the structure of target macromolecules. Molecular docking in drug design, its search algorithms, and scoring functions will be covered in the third part. Finally, a protocol of the Molecular Dynamics technique for studies of protein-ligand complexes and analysis of free energy of binding will be exposed in the last part.