**3.2 Baltimore classification**

This is based on the mechanism of mRNA production. Viruses produce proteins from their genomes and replicate themselves. Viral genome can be single-stranded (ss) and or double stranded (ds). ssRNA viruses may be either antisense (−) or sense (+) [11]. Viruses are classified in seven groups:

i. ssDNA viruses (+strand or sense) DNA (e.g., Parvovirus)

