건강과 대안 » 항체

[구제역] Foot and Mouth Disease(Fiebre Aftosa)

건강과대안 — Fri, 31 Dec 2010 11:31:48 +0000

미국 주류학계의 구제역에 대한 입장을 잘 정리한 자료입니다.

마지막 인간에게 미치는 영향(공중보건, Public Health)을 기술한 부분을 보면… 구제역이 인수공통전염병(zoonosis)라는 사실 자체는 부정하지 않고… 인체에 전염된 사례가 40건 정도 있긴 하지만 공중보건 상 고려해야 할 정도는 아니라는 입장을 개진하고 있습니다.

“구제역은 공중보건 상 문제가 될 것으로 고려되지 않는다. 인간에게 구제역 바이러스가 감염된 것은 1921년 후 40건 정도가 진단될 정도로 아주 드물다. (감염된 인간에서는) 병변 부위에 수포가 생기고, 인플루엔자와 유사한 증상이 나타날 수 있다. 이 질병은 일반적으로 약하게 증상이 나타나고, 바이러스가 인체에서 생존하는 기간이 짧으며, 인간대 인간 전염이 이루어지지 않아 감염이 제한적이다.(Foot-and-mouth disease is not considered to be a public health problem. FMDV infections in humans are very rare, with approximately 40 cases diagnosed since 1921. Vesicular lesions and influenza-like symptoms can be seen; the disease is generally mild, short-lived and self-limiting.)”

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Foot and Mouth Disease

Fiebre Aftosa

Last Updated: September 24, 2007

Importance
Foot-and-mouth disease (FMD) is a highly contagious viral disease that primarily affects cloven-hooved livestock and wildlife. Although adult animals generally recover, the morbidity rate is very high in naïve populations, and significant pain and distress occur in some species. Sequelae may include decreased milk yield, permanent hoof damage and chronic mastitis. High mortality rates can be seen in young animals. Although foot-and-mouth disease was once found worldwide, it has been eradicated from some regions including North America and most of Europe. Where it is endemic, this disease is a major constraint to the international livestock trade. Unless strict precautions are followed, FMD can be readily re-introduced into disease-free livestock. Once this occurs, the disease can spread rapidly through a region, particularly if detection is delayed. Outbreaks can severely disrupt livestock production, result in embargoes by trade partners, and require significant resources to control. Direct and indirect economic losses equivalent to several billion US dollars are not uncommon. Since 1997, a PanAsia lineage virus has caused a series of outbreaks in Asia, Africa, the Middle East and Europe. Some outbreaks, particularly those in Taiwan and the United Kingdom, have been devastating.

Etiology
The foot-and-mouth disease virus (FMDV) is a member of the genus Aphthovirus in the family Picornaviridae. There are seven immunologically distinct serotypes – O, A, C, SAT 1, SAT 2, SAT 3 and Asia 1 – and over 60 strains within these serotypes. New strains occasionally develop spontaneously.
FMDV serotypes and strains vary within each geographic region. Serotype O is the most common serotype worldwide. This serotype is responsible for a pan-Asian epidemic that began in 1990 and has affected many countries throughout the world. Other serotypes also cause serious outbreaks. Immunity to one serotype does not provide any cross-protection to other serotypes. Cross-protection against other strains varies with their antigenic similarity.

Transmission
FMDV can be found in all secretions and excretions from acutely infected animals, including expired air, saliva, milk, urine, feces and semen. Pigs, in particular, produce large quantities of aerosolized virus. Animals can shed FMDV for up to four days before the onset of symptoms. This virus is also found in large quantities in vesicle fluid, and peak transmission usually occurs when vesicles rupture. Transmission can occur by direct or indirect contact with infected animals and contaminated fomites; routes of spread include inhalation of aerosolized virus, ingestion of contaminated feed, and entry of the virus through skin abrasions or mucous membranes. The importance of each of these routes varies with the species. For example, pigs are less susceptible to aerosolized virus than cattle or sheep. Sheep may have less obvious symptoms than other species, and have been important in disseminating the virus in some outbreaks. Sexual transmission could be a significant route of spread for the SAT type viruses in African buffalo populations.
Some animals carry FMDV for prolonged periods after recovering from acute disease. Animals with natural or vaccine-induced immunity can also become carriers if they are later exposed to virus; these animals can remain asymptomatic.

FMDV can persist for up to nine months in sheep and up to four months in goats. Most cattle carry this virus for six months or less, but some animals remain persistently infected for up to 3.5 years. Individual African buffalo have been shown to be carriers for at least five years, and the virus can persist in a herd of African buffalo for at least 24 years. Llamas do not become carriers. A single study suggested that pigs may become carriers, but many other studies have found that this species cleared the infection within 3 to 4 weeks. In carriers, FMDV is found only in the esophageal-pharyngeal fluid.

The amount of virus is small, and it may be found only intermittently. Carriers might be able to transmit FMDV to other animals if they come in close contact; the importance of this route of transmission is controversial. Unequivocal evidence for transmission from carriers has been reported only from Africa, where African buffalo can spread the disease to cattle. With the exception of African buffalo, wildlife seems to be infected by contact with domesticated animals; FMDV disappears from the wildlife populations when outbreaks in livestock are controlled. Persistent infections have been reported in some experimentally infected wildlife including fallow (Dama dama) and sika deer (Cervus nippon) and kudu (Tragelaphus strepsiceros), and occasionally in red deer (Cervus elaphus). Deer could carry FMDV for up to 11 weeks.

FMDV can be transmitted on fomites including vehicles, as well as mechanically by animals and other living vectors. Airborne transmission can occur under favorable climatic conditions. FMDV is thought to have been transmitted via aerosols from Brittany to Jersey (approximately 30 miles or 48 km) and for approximately 70 miles (113 km) from Jersey to the Isle of Wight. There is limited information on the survival of FMDV in the environment, but most studies suggest that it remains viable, on average, for three months or less. In very cold climates, survival up to six months may be possible. Virus stability increases at lower temperatures; in cell culture medium at 4°C (39°F), this virus can remain viable for up to a year. It was reported to survive on bran and hay for more than three months in a laboratory. It can also remain viable for approximately two months on wool at 4°C, with significantly decreased survival when the temperature increases to 18°C (64°F), and for 2 to 3 months in bovine feces. Organic material protects the virus from drying, and enhances its survival on fomites. Virus survival is also enhanced when FMDV is protected from sunlight. FMDV is inactivated at pH below 6.5 or above 11. This virus can persist in meat and other animal products when the pH remains above 6.0,but it is inactivated by acidification of muscles during rigor mortis. It can survive for long periods in chilled or frozen lymph nodes or bone marrow.
In humans, FMDV may be carried in the nasal passages for a period of time. In one study, this virus was detected in the nasal passages of one of eight people 28 hours after exposure to infected animals, and from none of the eight at 48 hours. More recent studies have found that FMDV is not transmitted by people when personal hygiene and biosecurity protocols are followed, and suggest that nasal carriage of the virus may be unimportant. The discrepancy between these studies remains to be resolved.

Incubation Period
In cattle, the incubation period varies from two to 14 days, depending on the dose of the virus and route of infection. In pigs, the incubation period is usually two days or more, but can be as short as 18-24 hours. The incubation period in sheep is usually 3 to 8 days. Incubation periods as short as 24 hours and as long as 12 days have been reported in this species after experimental infection.

Good biosecurity measures should be practiced on uninfected farms to prevent entry of the virus.
Vaccination may be used to reduce the spread of FMDV or protect specific animals (e.g. those in zoological collections) during some outbreaks. The decision to use vaccination is complex, and varies with the scientific, economic, political and societal factors specific to the outbreak. Vaccines are also used in endemic regions to protect animals from clinical disease. FMDV vaccines must closely match the serotype and strain of the infecting strain. Vaccination with one serotype does not protect the animal against other serotypes, and may not protect the animal completely or at all from other strains of the same serotype. Currently, there is no universal FMD vaccine. Vaccine banks contain a wide variety of strains, particularly those judged to be the greatest threat of introduction, for use in an outbreak. Some countries maintain individual vaccine banks. There are also three international vaccine banks: the North American FMD Vaccine Bank (for Canada, the U.S. and Mexico), the E.U. Vaccine Bank (for all EU countries) and the International Vaccine Bank (for a variety of countries including Australia, New Zealand and some European nations).
Humans are thought to carry FMDV mechanically for a short period of time, based on a study that found this virus in the nasal passages of one of eight people 28 hours after they had been exposed to infected animals and none of the eight people at 48 hours. People who have been exposed to infected animals should avoid susceptible livestock for a designated period, usually a few days to a week. Some recent studies suggest that extended avoidance periods may not be necessary if good biosecurity practices, including effective personal hygiene protocols (showering or washing hands, and changing clothing), are followed. The discrepancy between these studies remains to be resolved, and government authorities should be consulted for the most recent waiting period recommendations.
Transmission of FMDV from wildlife in southern Africa is controlled by separating wildlife from domesticated livestock with fences, and by vaccination of livestock.

Public Health
Foot-and-mouth disease is not considered to be a public health problem. FMDV infections in humans are very rare, with approximately 40 cases diagnosed since 1921. Vesicular lesions and influenza-like symptoms can be seen; the disease is generally mild, short-lived and self-limiting.

[광우병] 캐나다에서 암, 광우병 모두 예방할 수 있는 항체 발견 주장

건강과대안 — Fri, 06 Aug 2010 16:31:21 +0000

캐나다의 브리티쉬 콜럼비아(BC) 대학교의 연구진들이 인간의 암과 동물의 소모성 뇌질환(광우병, 스크래피, 사슴의 만성소모성질환 등) 등의 진행을 중단시킬 수 있는 백신을 개발할 수 있는 길을 열어줄 수 있는 놀라운 연구결과를 발표했다는 소식입니다.

연구팀은 epitopes이라 불리는 항원(抗原) 결정기(決定基)에 작용하는 특정한 항체들을 분리해냈다고 합니다.

그런데 더욱 놀라운 것은 이 항체들이 특정 암세포에 반응을 했다고 합니다.

연구진의 희망은 이 항체들을 이용하여 암과 광우병을 동시에 예방할 수 있는 백신을 개발하는 것이라고 합니다.

물론 광우병과 관련하여 치료제나 예방약 개발했다는 주장이 과학적 사실임이 입증된 적은
한 번도 없습니다만… 이번 연구결과가 획기적 연구결과일지, 아니면 1회성 해프닝일지는
앞으로 과학계의 검증을 지켜보아야 할 것 같습니다.

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Unique link found between mad cow disease and cancer

Angela Mulholland, CTV.ca News Staff

Date: Monday Aug. 2, 2010 4:05 PM ET
http://www.ctv.ca/CTVNews/Health/20100730/prion-seiases-cancer-vaccine-100802/

Researchers led by University of British Columbia researcher Neil Cashman say they’ve made a surprise find about human cancer and brain-wasting diseases in animals that could pave the way for vaccines to halt all the diseases.

Cashman, a neurologist and researcher, was working on therapies for preventing transmissible spongiform encephalopathies, a group of animal brain-wasting diseases that include BSE in cows, scrapie in sheep, and chronic wasting disease in deer and other cervids.

Though the illnesses each affect different animals they are all caused by prions, which are unique infectious agents that cause the normal prion protein to go “rogue.”

Cashman explains that a protein is a chain of amino acids that only acquires its function by being folded properly. When a prion protein becomes misfolded after contact with another misfolded prion protein, it exposes certain regions in the normal prion protein, technically called “epitopes”.

His team had identified a group of antibodies they thought could target these epitopes, and thus halt the disease. But in order to test the antibodies, using a technique called “immunostaining,” they needed a line of easy-to-grow, regular cells to act as “negative controls.”

“And lo and behold, we found a few that stained intensely with these antibodies,” Cashman explained to CTV.ca.

Quite to Cashman’s surprise, some of the cancer cell lines reacted to the same antibody he was testing on prion-infected brain cells.

“We realized that if these [cancer] tumour cells stain for these antibodies, [the epitopes] could be a target for cancer immunotherapies,” Cashman said.

“We spent months trying to disprove the findings, thinking perhaps it was some kind of mistake. And eventually, we proved to our satisfaction that this antibody staining was real.”

He says teams at UBC and B.C. Cancer Research Centre are now testing how these antibodies can be used to develop a vaccine to treat cancer in mice.

If all goes well, it’s possible a vaccine could one day be tested on human cancers too, though Cashman cautions these are still “very early days.”

One aspect that makes dreams of a vaccine against cancer exciting is that the therapy would target only “misfolded” prion proteins, while sparing normal prion proteins. So unlike chemotherapies that kill off healthy cells along with cancer, therapies that target misfolded prion protein would attack only rogue cells, sparing the healthy ones.

Cashman said it’s possible that the same immunotherapy could also work in human prion diseases, such as “mad cow disease” and classical Creutzfeldt-Jakob Disease – but only if there were a way to identify infections in their earliest stages, before the illness caused symptoms.

“CJD is a very rapidly progressive disease, so by the time you make a definitive diagnosis, usually the patient has only a few weeks to live,” Cashman explained.

“Perhaps if we had a good diagnostic for the incubating phase [of CJD], then yes, it’s possible that a vaccine against these epitopes could block the infection before it gets to the brain. But that’s theoretical,” he said.

This new area of research is being funded under PrioNet Canada’s Bootstrap program and with the assistance of two industry partners: Amorfix Life Sciences Ltd.; and Saskatoon-based PREVENT – the Pan Provincial Vaccine Initiative.

Cashman is the scientific founder and board member of Amorfix, and is the scientific director of PrioNet Canada.