One Health

Zoonosis: General Info

• 60% of existing human diseases are zoonotic
• At least 75% of emerging infectious diseases in humans have an animal origin
• 80% of agents with potential bioterrorist use are zoonotic pathogens
• 5 new human diseases appear every year, with 3 of them being of animal origin
• One health approach is necessary to trace the origin of zoonotic viruses
• One health is not only about zoonoses, but also animals who are at threat from human viruses

SARS-CoV (2002-2003)

• Recombination and mutation events of the virus took place within bats
• Rapid mutations and successful spread among animals took place in wet markets, facilitated by stress, crowding, and immunosuppression
• In humans, several independent spillovers took place, with some strains of the virus undergoing further mutations, leading to an epidemic

MERS-CoV

• MERS-CoV in bats uses the same host receptor as MERS-CoV
• The virus originated in bats and spilled over into camels at least 30 years ago
• The virus is now prevalent in camels, and they have spread the virus to humans

SARS-CoV-2 (Covid-19)

• Bat CoV RaTG13 has 96% sequence homology with key differences in its genetic features
• The virus spread to pangolins and other intermediate hosts before spreading to humans in wet markets
• The spread of this virus to intermediate hosts is closely related to RBD
• Bat CoV RmYN02 has S1/S2 cleavage site insertion, 97% homology replicate gene, and 82% overall homology
• SARS-CoV-2 in humans acted similarly to FIP in cats, causing an increased release of cytokines (cytokine shower)
• The cytokine shower alone killed people, and for those who survived, it triggered a hyperimmune response, causing the release of inflammatory fluid, killing people by essentially drowning from fluid buildup in their lungs

Coronavirus: General Info

• Lessons from animal viruses aid in tackling emerging human viruses and vice versa
• CoV = coronavirus

Coronaviruses are Enigmatic due to their Behavior

• Pantropic Canine Coronavirus in dogs:
  • Started as causing self-limiting diarrhea in puppies and generally mild infection
  • Progressed to being a highly virulent pantropic CoV with acute systemic disease after 2006
  • Has tropism for internal organs and has a high case fatality
• TGEV to PRCoV in swine:
  • TGEV is an enteric virus that causes severe diarrhea and has a high mortality rate in piglets
  • TGEV had a part of its RNA removed, causing the virus to transform into PRCoV
  • PRCoV causes mild upper respiratory disease in pigs and induces an immunity against TGEV
• Feline Coronavirus in cats:
  • Causes FIP in 1-3% of cats with the virus
  • 70% of these cats will have a transient infection with mild diarrhea
  • 5-10% of these cats will have a resistant infection
  • FIP involves the cat's monocytes becoming infected, which triggers the release of cytokines (cytokine shower)
  • The cytokine shower causes systemic inflammation

Animal Coronavirus Vaccine Issues

• Lack of complete protection
• Short duration of immunity
• Virus shedding from vaccinated animals
• Correlates of protection against CoVs
• Emergence of multiple serotypes/subtypes, including virulent recombinants between vaccine and field strains
• ADE (antibody-dependent enhancement) enhanced disease

Learning from Coronaviruses in Animals

• Animal coronaviruses allow humans to learn from host-pathogen interactions in bats and other intermediate hosts
• Animal coronaviruses allow humans to learn from molecular epidemiology, pathogenesis, and therapeutic and prophylactic strategies in animals
• Enigmatic coronaviruses of animals have changes in viral genome that alter tissue tropism and pathogenicity
• Animal coronavirus vaccines have shown humans various strategies, whether or not they are effective, and possible side effects (ADE)
• The use of animal models teaches humans about pathogenesis, immune responses, therapeutics, diagnostics, and vaccines

One Health

• Pathogens and toxins are transmitted to the environment, animals, and humans through channels like water, soil, and animal handling
• Food safety requires teamwork to identify these channels
• The one health approach of "food safety" makes our food safer
• Risks of improper food safety can lead to Norovirus and Rotavirus in humans
• Food security is a threat of transboundary viral diseases, such as Rinderpest (in South Africa)
• One health plays a role in economics
• One health aids mental health by educating people about illnesses to prevent their ignorance and stereotyping
• The one health triad includes: healthy people, healthy environment, and healthy animals