Canine Distemper….in humans?

The Society for General Microbiology (#sgmman) is on for one more day so here is another quick post on viruses.

General schematic of Canine Distemper Virus
http://viralzone.expasy.org/all_by_protein/86.html

http://viralzone.expasy.org/all_by_protein/86.html
See supplemental material below.

Canine Distemper virus has a wide host range which include lions, tigers, hyenas, wolves, coyotes, raccoons, seals, martens, badger, bears and monkeys.

But not humans, not yet

Humans get measles, a closely related virus. So closely related that macaques and dogs vaccinated with measles are also immunized to CDV and monkeys vaccinated with CDV vaccine are protected from measles.

Measles and Canine Distemper Virus

• Paramyxoviridae family
• Morbillivirus genus
• single-stranded negative-sense RNA genome
• 15690 bases
• 150 nm

Interested to explore CDV’s potential to cross species and infect human hosts researchers from University of Würzburg and Bern tested the idea on two human cell lines that express the receptors targeted by the distemper virus – SLAM (aka CD150) and nectin-4.

One mutation, that’s all. 

The experiment found that a single mutation in the viral protein hemagglutinin (the “H” in H1N1) effectively improves the ability of distemper to bind human CD150 receptor; specifically a change from aspartic acid to lysine at position 540 and impressively, the change took only 3 passages.

As an interesting aside,it is believed that the measles virus emerged about 1000 years ago from the rinderpest virus

Of course receptor binding is only the first step in adapting to a new host, it takes a few more adaptive changes, though not as many as we would think.

A large un-vaccinated population makes a perfect evolutionary crucible; if CDV ever makes the jump to humans, I’m pointing the finger at the anti-vaxxers for giving evolution a helping hand.

Related Articles

• Bacterial pathogens: from natural ecosystems to human hosts
• Virus-host co-evolution: How specialised should a strain of a multi-host virus be?
• Pathogen evolution and disease emergence in carnivores
• Many Neglected Tropical Diseases May Have Originated in the Paleolithic or Before: New Insights from Genetics

REFERENCES

Bieringer, M., Han, W.J., Kendl, S., Khosravi, M., Plattet, P., and Schneider-Schaulies, J. (2013): Experimental adaptation of canine distemper virus (CDV) to the human entry receptor CD150. PLoS ONE 8(3): e57488. doi: 10.1371/journal.pone.0057488

Supplemental Material

Canine distemper virus NC_001921	Measles virus NC_001498
GI:9630646 PRODUCT:nucleocapsid protein N	GI:9626946 PRODUCT:nucleocapsid protein
GI:9630647 PRODUCT:phosphoprotein P	GI:9626947 PRODUCT:phosphoprotein P
GI:9630648 PRODUCT:C protein	GI:9626948 PRODUCT:C protein
GI:9630649 PRODUCT:matrix protein M	GI:9626949 PRODUCT:matrix protein M
GI:9630650 PRODUCT:fusion protein F	GI:9626950 PRODUCT:fusion protein
GI:9630651 PRODUCT:haemagglutinin protein H	GI:9626951 PRODUCT:hemagglutinin protein H
GI:9630652 PRODUCT:large polymerase protein L	GI:9626952 PRODUCT:large polymerase protein

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