HSPD1 and streptococcal pneumonia: Interestingly, as a chaperone protein, GroEL showed significant vaccine potential in many bacterial pathogens, such as Streptococcus pneumonia (Mohammed Nadeem et al., 2006), Bacillus anthracis (Sinha and Bhatnagar, 2010) and E. tarda (Liu et al., 2016).