Cholera epidemics in India in 1992 due to new V. cholerae 0139 generated by horizontal gene transfer from non-O1 strain to an earlier pandemic strain 01 EL Tor. The entire orientation of genetic engineering is to enhance horizontal gene transfer and to break down species barriers. It depends on vectors for multiplying and transferring genes made by recombining disease-causing viruses, plamids and transposons which carry and spread virulence and antibiotic resistance genes. Artificial vectors are chimaeric combinations which do not occur in nature. Artificial vectors have increased host ranges and increased tendency for horizontal gene transfer and recombination.
Artificial vectors contain antibiotic resistance genes as selectable markers.
Antibiotics increase the frequency of horizontal gene transfer 10 to 10000 fold. Current guidelines are based on old assumptions which have been overturned by recent scientific findings. Crippled laboratory strains of bacteria can survive in the environment. DNA released from dead and living cells persist in the environment and transform other bacteria. DNA resist digestion in the gut.