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[SANET-MG] transgenic cows with sythetic genes
Recently there has been publicity on USDA's introduction of cows with
synthetic genes. Essentially the synthetic genes are made up an
antibacterial gene from Staphylococcus (lyphostatin) joined to a gene
from a Streptococcus bacteria phage specifying endolysin that dissolves
bacteria. The genes are altered in DNA sequence and truncated. The
synthetic gene is used to modify cows so they produce milk that kills
bacteria. One problem discussed was allergy of the milk protein. It was
pointed out that the cows bearing the synthetic gene were unlikely to be
allergic to the toxin because it is a part of their genome thus
recognized as self. They failed to mention that kids drink the
allergenic milk and do not recognize it as self. Efforts were made to
alter the DNA sequences specify sugar additions to the protein to avoid
human allergy (allergy sites on proteins are often have signals for
sugar added to the protein) but that approach was only partly effective.
The problem I see is that USDA regulates the things that they own
patents for.The cows with synthetic genes are likely to cause a lot of
injury to people if they are rushed to commerce. However, USDAs
synthetic genes may solve on of Monsanto's greatest problems with its
growth hormone, that is the good news, the bad news is that kids who
drink the milk may suffer injury or death from allergy.
Publisher: Springer Netherlands
ISSN: 0962-8819 (Paper) 1573-9368
Issue: Volume 14, Number 5
Date: October 2005
Pages: 563 - 567
Engineering Disease Resistant Cattle
David M. Donovan1, David E. Kerr2 and Robert J. Wall1
Abstract Mastitis is a disease of the mammary gland caused by pathogens
that find their way into the lumen of the gland through the teat canal.
Mammary gland infections cost the US dairy industry approximately $2
billion dollars annually and have a similar impact in Europe. In the
absence of effective treatments or breeding strategies to enhance
mastitis resistance, we have created transgenic dairy cows that express
lysostaphin in their mammary epithelium and secrete the antimicrobial
peptide into milk. Staphylococcus aureus, a major mastitis pathogen, is
exquisitely sensitive to lysostaphin. The transgenic cattle resist S.
aureus mammary gland challenges, and their milk kills the bacteria, in a
dose dependent manner. This first step in protecting cattle against
mastitis will be followed by introduction of other genes to deal with
potential resistance issues and other mastitis causing organisms. Care
will be taken to avoid altering milk’s nutritional and manufacturing
properties. Multi-cistronic constructs may be required to achieve our
goals as will other strategies possibly involving RNAi and gene
targeting technology. This work demonstrates the possibility of using
transgenic technology to address disease problems in agriculturally
Applied and Environmental Microbiology, April 2006, p. 2988-2996, Vol.
72, No. 4
Peptidoglycan Hydrolase Fusions Maintain Their Parental Specificities
David M. Donovan,1* Shengli Dong,2 Wes Garrett,1 Geneviève M. Rousseau,3
Sylvain Moineau,3 and David G. Pritchard2
The increased incidence of bacterial antibiotic resistance has led to a
renewed search for novel antimicrobials. Avoiding the use of broad-range
antimicrobials through the use of specific peptidoglycan hydrolases
(endolysins) might reduce the incidence of antibiotic-resistant
pathogens worldwide. Staphylococcus aureus and Streptococcus agalactiae
are human pathogens and also cause mastitis in dairy cattle. The
ultimate goal of this work is to create transgenic cattle that are
resistant to mastitis through the expression of an antimicrobial
protein(s) in their milk. Toward this end, two novel antimicrobials were
produced. The (i) full-length and (ii) 182-amino-acid, C-terminally
truncated S. agalactiae bacteriophage B30 endolysins were fused to the
mature lysostaphin protein of Staphylococcus simulans. Both fusions
display lytic specificity for streptococcal pathogens and S. aureus. The
full lytic ability of the truncated B30 protein also suggests that the
SH3b domain at the C terminus is dispensable. The fusions are active in
a milk-like environment. They are also active against some lactic acid
bacteria used to make cheese and yogurt, but their lytic activity is
destroyed by pasteurization (63°C for 30 min). Immunohistochemical
studies indicated that the fusion proteins can be expressed in cultured
mammalian cells with no obvious deleterious effects on the cells, making
it a strong candidate for use in future transgenic mice and cattle.
Since the fusion peptidoglycan hydrolase also kills multiple human
pathogens, it also may prove useful as a highly selective,
multipathogen-targeting antimicrobial agent that could potentially
reduce the use of broad-range antibiotics in fighting clinical infections.
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