Influenza C virus is the only species in the genus Gammainfluenzavirus, in the virus family Orthomyxoviridae, which like other influenza viruses, causes influenza.
Influenza C viruses are known to infect humans and pigs.[1]
Flu due to the Type C species is rare compared with Types B or A, but can be severe and can cause local epidemics. Type C has 7 RNA segments and encodes 9 proteins, while Types A and B have 8 RNA segments and encode at least 10 proteins.
Influenza viruses are members of the family Orthomyxoviridae.[2] Influenza viruses A, B, C, and D represent the four antigenic types of influenza viruses.[3] Of the four antigenic types, influenza A virus is the most severe, influenza B virus is less severe but can still cause outbreaks, and influenza C virus is usually only associated with minor symptoms.[4][5][6][7]
Influenza D virus is 50% similar in amino acid composition to influenza C virus, similar to the level of divergence between types A and B, while types C and D have a much greater level of divergence from types A and B.[8][9] Influenza viruses C and D were estimated to have diverged from a common ancestor over 1,500 years ago, around 482 AD.[8] Influenza viruses A and B are estimated to have diverged from a single ancestor around 4,000 years ago, while the ancestor of influenza viruses A and B and the ancestor of influenza virus C are estimated to have diverged from a common ancestor around 8,000 years ago.[10]
Influenza A virus can infect a variety of animals as well as humans, and its natural reservoir (natural host) is birds, whereas influenza viruses B, C, and D do not have animal reservoirs.[4][11][8] Influenza C virus is not as easily isolated so less information is known of this type, but studies show that it occurs worldwide.[12] Influenza C virus currently has 6 lineages, which were estimated to have emerged around 1896 AD.[8]
This virus may be spread from person to person through respiratory droplets or by fomites (non-living material) due to its ability to survive on surfaces for short durations.[4] Influenza viruses have a relatively short incubation period (lapse of time from exposure to pathogen to the appearance of symptoms) of 18–72 hours and infect the epithelial cells of the respiratory tract.[4] Influenza virus C tends to cause mild upper respiratory infections.[13] Cold-like symptoms are associated with the virus including fever (38–40 °C), dry cough, rhinorrhea (nasal discharge), headache, muscle pain, and achiness.[4][14] The virus may lead to more severe infections such as bronchitis and pneumonia.[13]
After an individual becomes infected, the immune system develops antibodies against that infectious agent. This is the body's main source of protection.[4] Most children between five and ten years old have already produced antibodies for influenza virus C.[14] As with all influenza viruses, type C affects individuals of all ages, but is most severe in young children, the elderly and individuals with underlying health problems.[4][15] Young children have less prior exposure and have not developed the antibodies and the elderly have less effective immune systems.[4] Influenza virus infections have one of the highest preventable mortalities in many countries of the world.[15]
Influenza viruses, like all viruses in the family Orthomyxoviridae, are enveloped RNA viruses with single stranded genomes.[2] The antigens, matrix protein (M1) and nucleoprotein (NP), are used to determine if an influenza virus is type A, B, C, or D.[4] The M1 protein is required for virus assembly and NP functions in transcription and replication.[16][17] These viruses also contain proteins on the surface of the cell membrane called glycoproteins. Type A and B have two glycoproteins: hemagglutinin (HA) and neuraminidase (NA). Types C and D have only one glycoprotein: hemagglutinin-esterase fusion (HEF).[4][18][8] These glycoproteins allow for attachment and fusion of viral and cellular membranes. Fusion of these membranes allows the viral proteins and genome to be released into the host cell, which then causes the infection.[19] Types C and D are the only influenza viruses to express the enzyme esterase. This enzyme is similar to the enzyme neuraminidase produced by Types A and B in that they both function in destroying the host cell receptors.[13] Glycoproteins may undergo mutations (antigenic drift) or reassortment in which a new HA or NA is produced (antigenic shift). Influenza virus C is only capable of antigenic drift whereas Type A undergoes antigenic shift, as well. When either of these processes occur, the antibodies formed by the immune system no longer protect against these altered glycoproteins. Because of this, viruses continually cause infections.[4]
Influenza virus C is different from Types A and B in its growth requirements. Because of this, it is not isolated and identified as frequently. Diagnosis is by virus isolation, serology, and other tests.[14] Hemagglutination inhibition (HI) is one method of serology that detects antibodies for diagnostic purposes.[12] Western blot (immunoblot assay) and enzyme-linked immunosorbent assay (ELISA) are two other methods used to detect proteins (or antigens) in serum. In each of these techniques, the antibodies for the protein of interest are added and the presence of the specific protein is indicated by a color change.[20] ELISA was shown to have higher sensitivity to the HEF than the HI test.[11] Because only Influenza viruses C and D produce esterase, In Situ Esterase Assays provide a quick and inexpensive method of detecting just Types C and D.[13] If more individuals were tested for Influenza virus C as well as the other three types, infections not previously associated with Type C may be recognized.[13]
Because influenza virus A has an animal reservoir that contains all the known subtypes and can undergo antigenic shift, this type of influenza virus is capable of producing pandemics.[11] Influenza viruses A and B also cause seasonal epidemics almost every year due to their ability to antigenic drift.[3] Influenza virus C does not have this capability and it is not thought to be a significant concern for human health.[11] Therefore, there are no vaccinations against influenza virus C.[4]
Influenza C virus is the only species in the genus Gammainfluenzavirus, in the virus family Orthomyxoviridae, which like other influenza viruses, causes influenza.
Influenza C viruses are known to infect humans and pigs.
Flu due to the Type C species is rare compared with Types B or A, but can be severe and can cause local epidemics. Type C has 7 RNA segments and encodes 9 proteins, while Types A and B have 8 RNA segments and encode at least 10 proteins.
El influenzavirus C es un género perteneciente a la familia de virus Orthomyxoviridae, que incluye a los virus que causan gripe (influenza). La única especie en este género es el virus influenza C. Son virus que se sabe infectan a humanos y cerdos, pero por lo general no produce epidemias y sólo provoca infecciones sin síntomas o con cuadros clínicos poco trascendentes, aunque en casos aislados puede causar enfermedad severa y epidemias localizadas.
El influenzavirus C es un género perteneciente a la familia de virus Orthomyxoviridae, que incluye a los virus que causan gripe (influenza). La única especie en este género es el virus influenza C. Son virus que se sabe infectan a humanos y cerdos, pero por lo general no produce epidemias y sólo provoca infecciones sin síntomas o con cuadros clínicos poco trascendentes, aunque en casos aislados puede causar enfermedad severa y epidemias localizadas.
Cet article court présente un sujet plus développé dans : virus de la grippe C.
Gammainfluenzavirus est un genre de virus à ARN monocaténaire de polarité négative de la famille des Orthomyxoviridae. Ce genre contient une seule espèce de virus répertoriée : le virus de la grippe C.
Cet article court présente un sujet plus développé dans : virus de la grippe C.
Gammainfluenzavirus est un genre de virus à ARN monocaténaire de polarité négative de la famille des Orthomyxoviridae. Ce genre contient une seule espèce de virus répertoriée : le virus de la grippe C.
Gammainfluenzavirus è un genere di virus appartenente alla famiglia degli Orthomyxoviridae, in grado di infettare gli umani e i suini. L'unica specie appartentente è il virus dell'influenza C.
Influenzavirus C é um género da família de vírus Orthomyxoviridae e que provoca a gripe. A única espécie deste género é denominada vírus influenza C e afeta seres humanos e porcos.[1] A gripe do tipo C é rara quando comparada com os tipos A e B, mas pode ser igualmente grave e provocar epidemias locais. O subtipo C tem sete segmentos de ARN e codifica nove proteínas, enquantos os tipos A e B têm 8 segmentos de ARN e codificam, no mínimo, 10 proteínas.[2]
Influenzavirus C é um género da família de vírus Orthomyxoviridae e que provoca a gripe. A única espécie deste género é denominada vírus influenza C e afeta seres humanos e porcos. A gripe do tipo C é rara quando comparada com os tipos A e B, mas pode ser igualmente grave e provocar epidemias locais. O subtipo C tem sete segmentos de ARN e codifica nove proteínas, enquantos os tipos A e B têm 8 segmentos de ARN e codificam, no mínimo, 10 proteínas.
인플루엔자바이러스 C형(Influenzavirus C)은 오르토믹소바이러스과를 이루는 속(屬)의 하나이다. 이 속으로 분류되는 바이러스는 C형 인플루엔자 바이러스(Influenza C virus) 하나뿐이다. 인플루엔자바이러스 C형으로 분류되는 바이러스는 오로지 사람과 돼지만을 숙주로 삼는다고 알려져 있으며[1], 감염되면 숙주에게 인플루엔자를 일으킨다. 인플루엔자바이러스 A형이나 B형에 비해 발병 빈도는 적지만, 일단 감염되면 심각한 상태를 일으키고, 국소적인 유행을 일으킬 수도 있다. 그러나 다른 인플루엔자 바이러스에 비해서 변이 속도가 느리기 때문에 범유행을 일으키지는 않는다. 인플루엔자바이러스 C형에 대한 백신은 2010년 3월 현재 개발된 것이 없다.[2]
유전물질로는 단일가닥 RNA를 가지고 있다. 총 9개의 단백질은 7개의 RNA 가닥에 나뉘어 담겨 있다.[3] 이에 비해 인플루엔자바이러스 A형이나 인플루엔자바이러스 B형은 8개의 RNA 세그먼트를 가지고, 10개 이상의 단백질로 구성되어 있다. 인플루엔자바이러스 D형은 아미노산 구성이 인플루엔자바이러스 C형과 59% 유사하다. 인플루엔자 바이러스 C와 D는 지금으로부터 약 1,500년 전 약 482년에 분기된 것으로 추정된다.[4] 인플루엔자바이러스 C형은 현재 숙주로부터 다른 종의 숙주로 쉽게 옮겨가지 않으므로, 발생 빈도가 낮아 연구 결과가 적다. 인플루엔자바이러스 C형은 현재 6개의 계통이 있으며, AD 1896년 경에 발현한 것으로 추정한다.[5]
인플루엔자바이러스 C형은 호흡기에서 발생하는 비말이나, 비생물 접촉 물질에 의해서 전파될 수 있다.[6] 인플루엔자바이러스는 잠복기간이 약 18-72시간이며, 호흡기의 상피 세포를 감염시킨다.[6] 인플루엔자바이러스 C형은 경증의 상부 호흡기 감염을 일으키는 경향이 있다. 감기와 유사한 증상을 발현시키며, 열(38–40°C), 마른 기침, 비염(비강 분비물 과다 발생), 두통, 근육통 및 무력감을 가져올 수 있다. 기관지염 및 폐렴과 같은 더 심각한 감염을 일으킬 수 있다.[7]
|date= (도움말) |date= (도움말) 인플루엔자바이러스 C형(Influenzavirus C)은 오르토믹소바이러스과를 이루는 속(屬)의 하나이다. 이 속으로 분류되는 바이러스는 C형 인플루엔자 바이러스(Influenza C virus) 하나뿐이다. 인플루엔자바이러스 C형으로 분류되는 바이러스는 오로지 사람과 돼지만을 숙주로 삼는다고 알려져 있으며, 감염되면 숙주에게 인플루엔자를 일으킨다. 인플루엔자바이러스 A형이나 B형에 비해 발병 빈도는 적지만, 일단 감염되면 심각한 상태를 일으키고, 국소적인 유행을 일으킬 수도 있다. 그러나 다른 인플루엔자 바이러스에 비해서 변이 속도가 느리기 때문에 범유행을 일으키지는 않는다. 인플루엔자바이러스 C형에 대한 백신은 2010년 3월 현재 개발된 것이 없다.
