[ACVM] To heat inactivate or not heat inactivate ... that's the question; MORE Serious Problem

Krakowka, George krakowka.1 at osu.edu
Wed Jun 15 09:05:19 EDT 2016 

In my opinion, the only way to test for various pathogens in avian serum is to do ELISAs BEFORE heat inactivation. Of course the major caveat:  You can ONLY look for pathogens that you know about....What about the ones that we don't know about and have no "test" for them????  74C seems extreme versus 56C for 30 minutes. Is chicken serum complement (assuming that they have this) only susceptible to 74C??? Seems to me that somebody in avian immunology must know about this...... Regards to all, Steve Krakowka
________________________________________
From: ACVM_diplomates [acvm_diplomates-bounces+krakowka.1=osu.edu at lists.osu.edu] on behalf of Dr. Arun Kulkarni [akulkarni at gapoultrylab.org]
Sent: Wednesday, June 15, 2016 8:54 AM
To: ACVM - The American College of Veterinary Microbiologists Listserv; discussion at aavld.org
Subject: Re: [ACVM] To heat inactivate or not heat      inactivate      ...     that's  the     question; MORE Serious Problem

Thank you all for the input.

I am facing more serious problem.

 I just reviewed two USDA import permits (Form VS16-6A) for chicken serum. This chicken serum will be tested for various poultry pathogens using commercial ELISA kits.  USDA is asking the importer

to heat inactivate the serum at 74 C for 30 min before shipping it to the US.  We certainly do not want to bring any foreign animal disease to the US; however I seriously doubt the science (and wisdom) behind this.  Is chicken serum complement so heat resistant? What surprised me that the people are justifying that ELISA titers are good even after heating(?).  Here is my take:

It is well-known that proteins are denatured at high temperature.  If the hypervariable domain of the Fab-region of antibody undergoes conformational change due to heat, how will it interact with

the bound antigen on the coated plate in an epitope-specific way? Even if it binds just like any protein binding to another protein in a non-specific way, so called "titer" end point may not be the

correct reflection of specific binding.

Can someone offer more explanation please? Thanks,

Arun Kulkarni, BVSc, MVSc, PhD, dACVM
Virology Director,
Georgia Poultry Laboratory,
3235 Abit Massey Way
Gainesville, GA 30507
tel: 770-766-6827 (w)



-----Original Message-----
From: ACVM_diplomates [mailto:acvm_diplomates-bounces+akulkarni=gapoultrylab.org at lists.osu.edu] On Behalf Of Tewari, Deepanker
Sent: Tuesday, June 14, 2016 11:14 PM
To: ACVM - The American College of Veterinary Microbiologists Listserv; discussion at aavld.org
Subject: Re: [ACVM] To heat inactivate or not heat inactivate ... that's the question

Agree, C inact. is the main reason for heat treatment at 56. More important during testing assays (e.g. SN) to stay consistent and avoid any outside influence.

Complement in presence of any abodies in serum (even low level) has been shown to activate C. Alternatively, certain pathogens are known to activate C with direct binding.

Good one Jerry,

Thanks
Deep Tewari

Sent from my Verizon Wireless 4G LTE smartphone


-------- Original message --------
From: Yan.Zhang at Agri.ohio.gov
Date: 06/14/2016 4:35 PM (GMT-05:00)
To: ACVM - The American College of Veterinary Microbiologists Listserv <acvm_diplomates at lists.osu.edu>, discussion at aavld.org
Subject: Re: [ACVM] To heat inactivate or not heat inactivate ... that's the question

I believe the heat inactivation is to inactivate the complement in the fetal bovine serum so that your assays (virus isolation, virus neutralization and etc) will not be affected.

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Yan Zhang, DVM, Ph.D, DACVM
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-----Original Message-----
From: ACVM_diplomates [mailto:acvm_diplomates-bounces at lists.osu.edu] On Behalf Of Krakowka, George
Sent: Tuesday, June 14, 2016 3:24 PM
To: ACVM - The American College of Veterinary Microbiologists Listserv; discussion at aavld.org
Subject: Re: [ACVM] To heat inactivate or not heat inactivate ... that's the question

We done this since the beginning of time (1971 at least) but probably because we have always done it.  I have to believe that Heat Inactivation did some good although what I am not too sure. Regardless, I am reluctant to change this part of the SOP now in case there ARE differences between them and these are reflected in viral titrations, etc etc etc, Steve Krakowka) ________________________________________
From: ACVM_diplomates [acvm_diplomates-bounces at lists.osu.edu] on behalf of Jerry Saliki [jsaliki at uga.edu]
Sent: Tuesday, June 14, 2016 12:45 PM
To: discussion at aavld.org; ACVM - The American   College of Veterinary Microbiologists Listserv
Subject: [ACVM] To heat inactivate or not heat inactivate ... that's the        question

To all of you cell culturists out there, I wonder if you still heat inactivate your fetal bovine serum prior to use in cell cultures and other assays. And if you heat inactivate, is it because it has been in your SOP forever or because you actually believe heat inactivation is beneficial?

________________________________________
Jeremiah T. Saliki, DVM, PhD, DACVM
Professor and Director
Athens Veterinary Diagnostic Laboratory
University of Georgia, Athens GA 30602
Tel: 706-542-5568
Website: www.ugavetlab.org<http://www.ugavetlab.org/>

Reminder: This message and any responses to it constitute public records that may be made publicly available to anyone who requests them.
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