Zoonosic Viruses PDF

Zoonotic viruses Dr. Marine Petit [email protected] Virology Lectures in BMS2037 • Introduction to Virology & Virus structure and Classification • Clinical Virology and diagnostics • Virology practical • The infectious cycle of virus replication mechanisms • Gastroenteritis viruses • Respirato...

Zoonotic viruses Dr. Marine Petit [email protected] Virology Lectures in BMS2037 • Introduction to Virology & Virus structure and Classification • Clinical Virology and diagnostics • Virology practical • The infectious cycle of virus replication mechanisms • Gastroenteritis viruses • Respiratory viruses • Zoonotic viruses Zoonotic viruses learning outcomes Appreciate the emergence potential of Zoonoses Learn about a few important Zoonotic viruses Understand key facts including: Virology Pathogenesis Treatment One Health approach Similarities and differences between Zoonoses Viral Zoonoses Viral Zoonoses Vector Borne Food Borne Air Borne Over 90% of all human viruses known today were unknown at the end of World War II Viral Zoonoses – Bigger risk for the Global South Definitions Spillover: The transmission of a pathogen from an animal to a human. In most cases, spillover does not cause the human to get sick or transmit the pathogen to other humans. Shedding: The release of a virus from an infected person into the environment. Those pathogens that have been shed into the environment can often be infectious, and this is how the pathogen gets transmitted from one person to another. Zoonosis: A pathogen/virus that has spread from animals to humans. Not all pathogens are zoonoses. Important info! Spillover Spillover Reservoir: The place where a pathogen normally lives and reproduces. Vector: An organism that transmits a pathogen to other organisms. Host: A human or animal that is a carrier for a pathogen. Spillover 1.Contact Spillover 1.Contact Virus exchange between donor and recipients Takes place by chance Spillover Important info! 1.Contact Virus exchange between donor and recipients Takes place by chance Recipient cells need to have the right receptors Spillover 1.Contact Virus exchange between donor and recipients Takes place by chance Recipient cells need to have the right receptors Closest host genetically have more chance to get similar cell receptors Spillover 2. Infection When the spillover event occurs Spillover 3. Transmission Infected person transmit viruses to other people. The jump from animal to human is complete. Spillover barrier Increasing the risk of Spillover Wet market Close contact with animal Husbandry Destruction of natural environment Wild life illegal trade Wild life hunting Viral Zoonoses – Are we doing enough? State of the research Recent Spillover in human population Coronavirus 252,000 publications Ebola 11,877 publications Viral Zoonoses – Are we doing enough? State of the research Recent Spillover in human population Coronavirus 252,000 publications Ebola 11,877 publications Up-coming Spillover in human population Nipah virus 1,368 publications Crimea-Congo hemorrhagic fever 17 publications How do we prioritise? Human transmissibility (or likelihood). What’s the R0? R0 = Basic reproduction number or R naught or R zero Different for all viruses, even if they have the same transmission mode Important info! How do we prioritise? Human transmissibility (or likelihood). What’s the R0? Case fatality rate (Hendra=60%!) Spillover potential Evolutionary potential Available countermeasures (vaccines antivirals) Difficulty of detection Public health aspect of the affected area (is there good health & research infrastructure?) Potential scope of outbreak Potential societal impacts How do we prioritise? How do we fight Zoonotic viruses? Spread knowledge in and out the lab And connect with public actors to design new policy Important info! eradication of Rabies –One health approach Strong case for integrated controls Management of rabies in animals as a key public health intervention Tools are available (Vaccine for animal and human), they just need to be properly applied Policy makers need to acknowledge the problem eradication of Rabies –One health approach Strong case for integrated controls Management of rabies in animals as a key public health intervention Tools are available (Vaccine for animal and human), they just need to be properly applied Policy makers need to acknowledge the problem Diagnosis and surveillance Wildlife and human Vaccination campaign Vet and Medical doctors together Study of the Rabies virology to predict the epidemics If we work in collaboration, we could eradicate Rabies epidemics eradication of Rabies –One health approach 5 min Break Surrey attendance code: The Ebola outbreak: 2013-2016 Multiple Ebola outbreaks Ebolavirus-virology Classification: Enveloped, negative sense ssRNA genome Mononegavirales –Filoviridae – Ebolavirus Viral strains: 6 main strains identified named after their place of discovery: Tai forest ebolavirus, Zaire ebolavirus 30-40% variations in sequence between strains. Description: 1 segment encoding 7 proteins 4 non-structural proteins and 3 structural proteins Important info! Ebolavirus-virology EBOLA-disease Incubation periods from 3 days to 3 weeks Hemorrhagic fever in Human and other non-human primates Non-specific symptoms: Fever, sore throat, muscle pain and headaches Severe cases symptoms: Vomiting, diarrhea, rash and decreased liver and kidney function Death often causes by shock from fluid loss, 6 to 16 days after the first symptoms Ebolavirus kills 50% of those infected Virus spreads through direct contact with body fluids of infected human/animal or fomite Important info! Ebolavirus Ecology Enzootic Cycle: Enzootic means “native” to the place. An infection is enzootic in a population when the infection is maintained in the population without the need for external inputs. Could also refer as endemic disease VERSUS Epizootic cycle: epi “upon” + “zootic” animal in Greek. Epizootic viral disease occurs in a special place (an outbreak) and target non-human animals. Could also refer as epidemic disease Important info! Ebolavirus Diagnosis and treatment Diagnosis: Isolating the virus, detecting its RNA (PCR) or proteins (ELISA), or detecting antibodies against the virus in a person's blood. Nipah virus Nipah virus outbreaks Natural host: Pteropodidae family of fruit bats Virus first appeared in Malaysia in 1998 Infections previously reported in Malaysia, Singapore, Bangladesh, and India. More than 260 people have been killed by the virus worldwide since 1998 Important info! Nipah virology Classification: Enveloped, negative sense ssRNA genome Mononegavirales –Paramyxoviridae – Henipavirus Viral strains: Henipavirus is including Hendra (Australia), and Nipah (Malaysia) viruses. Description: 1 segment encoding 9 proteins 5 non-structural proteins and 4 structural proteins Important info! Nipah virus disease Incubation period is 4 to 14 days Transmission from infected bats or pigs, also by contaminated food, or human to human contact Non-specific symptoms: Flu-like, fever and sometimes diarrhea, and vomiting. Severe symptoms: Pneumonia, encephalitis and/or meningitis. Disease can be also observed in pigs Rapid progression to critical illness occurs in 60% of infected people. Nipah virus kills 40 to 75% of infected patient. Important info! Encephalitis detection by Magnetic resonance imaging Nipah virus Diagnosis & Treatment No treatment or vaccine is available for Nipah virus Primary treatment is supportive care for infected people Initial signs and symptoms of Nipah virus infection are nonspecific, and the diagnosis is often not suspected at the time of presentation. The main tests used are real time polymerase chain reaction (RT-PCR) from bodily fluids to detect viral RNA and antibody detection via enzyme-linked immunosorbent assay (ELISA). Crimea-Congo Hemorrhagic Fever virus Crimea-Congo Hemorrhagic fever -Outbreaks Hosts Goats Cattle Dead-end host Vectors Outbreaks three billion people are at risk of infection globally, and 10,000 to 15,000 infections — 500 death— occur every year. Hotspot: Turkey, Albania, Georgia (2023) Crimea-Congo Hemorrhagic fever -virology Classification: Enveloped, negative single stranded RNA genome Bunyavirales –Nairoviridae – Orthonairovirus Viral strains: Genetic diversity link to geographic localization Biggest amino acids diversities in GPC Description: 3 segments encoding 4 proteins 1 non-structural proteins and 3 structural proteins Important info! Crimea-Congo Hemorrhagic fever -disease Crimea-Congo Hemorrhagic fever (CCHF) virus Incubation period 7 days Nonspecific symptoms : Fever, fatigue, and myalgia, diarrhea and vomiting. Severe symptoms: Thrombocytopenia (low platelets causing bleeding), hemorrhagic manifestation like ecchymosis. Mild to severe hemorrhagic fever, exclusively in humans (dead-end host) Symptoms are due to: High viremia Low antibody counts High pro-inflammatory cytokines Multi-organ infection causing organs failure CCHF outbreaks have a case fatality rate of up to 40% Important info! Important info! Crimea-Congo Haemoraghic fever –The tick vector Crimea-Congo Haemoraghic fever –The tick vector Crimea-Congo Haemoraghic fever –The tick vector Hyalomma tick species Chasing tick Warm and dry climate CCHFV – diagnosis and treatment Diagnosis: Treatment: Very difficult because low to no antibody detected in patients. Main way of detection viral RNA (RT-PCR) or virus detection in blood (microscopy). No Human or Animal vaccine No specific treatment Ribavirin (antiviral drogue that stop viral RNA synthesis) Testing patient is very hazardous and risky, must be done in high containment laboratory. Important info! BSL-4 facilities World wide CCHFV – prevention is our best tool Develop vector control strategies • By understanding how virus and tick interact researcher try to find ways to stop the viral transmission from tick to vertebrates. • Development of an anti-tick vaccine targeting tick saliva proteins to attract immune cells on the place of infection. CCHFV – prevention is our best tool Develop vector control strategies • By understanding how virus and tick interact researcher try to find ways to stop the viral transmission from tick to vertebrates. • Development of an anti-tick vaccine targeting tick saliva proteins to attract immune cells on the place of infection. If you want to participate to tick-borne virus research, you could apply to summer school or join my lab next year for the research lab project! Movie on viral emergence: Contagion Soderbergh #VaccineWorks You are now expert in virology and understand more than the general population, so please spread your knowledge Link to go further Health care lessons for rich countries from the Global South : Goats and Soda : NPR https://www.npr.org/sections/goatsandsoda/2023/02/04/1149848139/understanding-the-vocabulary-ofspillover-viruses https://speakingofmedicine.plos.org/2014/11/11/factors-might-led-emergence-ebola-west-africa/ https://www.nytimes.com/interactive/2014/12/30/science/history-of-ebola-in-24-outbreaks.html Scientific literature https://www.nature.com/articles/nrmicro.2017.45 Definition + Barrier link to spillover https://www.nature.com/articles/s42003-022-03797-9 Model to predict spillover risk https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4848600/ CCHFV descriptions Videos on Zoonosis https://youtu.be/lFo_NAHupZY?si=kEJKEUVcthyyQXAX One health Literature