Abstract: AimTo explore the changes of rat platelet phospholipase A₂ (PLA₂) mRNA content in bacteria infected rat and study the cDNA and amino acid sequences of the PLA₂ structure to lay a good foundation for the development of new antibiotics. MethodsThe PLA₂ mRNA level in blood was determined by RT-PCR. The DNA sequence was cloned and analyzed. ResultsAfter injection of bacteria in rats, the mRNA level of PLA₂ in blood increased markedly. The cDNA and amino acid sequence were highly homologous to other PLA₂ cDNA from different tissues of the rat. ConclusionPlatelet PLA₂ in blood responded quickly to bacteria infection in gene level. Therefore, the PLA₂ protein was produced increasingly which was shown to control the infection with bacteria. Although there are little difference between PLA₂ cDNA cloned from blood and other sources in DNA and amino acid sequences, the catalytic site for enzymatic activity and basic structure are identical.