Feline leukemia virus
Encyclopedia
Feline leukemia virus is a retrovirus
that infects cat
s. FeLV can be transmitted between infected cats when the transfer of saliva or nasal secretions is involved. If not defeated by the animal’s immune system
, the virus can be lethal. The disease caused by this virus is a form of cancer of the blood cells called lymphocytes (a leukemia
).
(swollen lymph nodes), skin lesions, fatigue, fever
, weight loss
, stomatitis
, gingivitis
, litter box avoidance, pancytopenia
, poor grooming, recurring bacterial and viral illnesses, anemia
, diarrhea
, and jaundice
.
s infected with FeLV can serve as sources of infection. Transmission is related to the subgroup (see below). Cats can possibly pass the virus between themselves through saliva and close contact, by biting another cat, through a litter box or food dish used by an infected cat (rarely happens), and from milk during nursing. Transmission can also take place from an infected mother cat to her kittens, either before they are born or while they are nursing.
Initially thought to survive only about 2 hours in a dry environment, and about 48 hours in a damp environment (such as a litter box) a new paper published by Cornell vets (http://www.vet.cornell.edu/FHC/news/) titled "Can FeLV survive in the environment?" likened FeLV to HIV (which can survive for several weeks in the environment and is structurally related to FeLV). In the absence of any meaningful studies in to the survival of FeLV in the environment, it may be sensible to exercise caution when assuming FeLV survival in the environment is so short (2 hours to 2 days).
FeLV causes immunosuppression
in pet cats, and there is also evidence for existence of the virus in larger wild cat populations also (e.g. lynx
, cheetah
s, and lion
s). Overwhelming epidemiologic
evidence suggests FeLV is not transmissible to either humans or dogs. This statement is based on the fact that approximately one pet dog in five lives with a cat, and all pet cats live with humans (some 60 million pet cats in the USA). It is species-specific, and does not infect other animals, such as dogs (in fact, there is apparently no canine version of this disease at all).
Approximately 0.5% of pet cats are persistently infected with FeLV, but many more pet cats (>35%) have specific IgG antibodies which indicate prior exposure and subsequent development of immunity instead of infection
. Transmission of FeLV is mainly via saliva
and friendly behaviors, such as sharing feeding bowls and mutual grooming (as distinct from fighting and biting).
There is strong evidence kittens under 4 months of age are susceptible to infection, but by 8 months are resistant to it.
Kittens can be born with it, having contracted it from their mother while in utero.
Infection is far higher in city cats, stray or owned, than in rural cats: this is entirely due to the amount of contact the cats have with each other.
Four subgroups of FeLV exist: A; B; C, and T, but only subgroup A is transmissible between cats. The other subgroups arise de novo and as results of recombination
with an endogenous DNA feline sequence. Hence, there is very good evidence this virus is quite ancient, and may well have evolved more than one time over the last 10,000,000 years.
Subgroups are defined on the basis of viral interference and in vitro host range. The differences are due to polymorphism in the envelope glycoprotein gp70 with the highest level of divergence lying in the region of gp70 which is thought to interact with the cellular receptor. In an infected cell, gp70 is thought to block viral receptors, so preventing further infection by the same subgroup.
Once the virus has entered the cat, there are six phases to a FeLV infection:
If the cat's immune system does not fight off the virus, then it goes onto:
Cats diagnosed as persistently infected by ELISA
testing may die within a few months or may remain asymptomatic for longer. The fatal diseases are leukemias, lymphomas
, and non-regenerative anemias. Although there is no known cure for the virus infection, in 2006 the United States Department of Agriculture approved Lymphocyte T-Cell Immunomodulator as a treatment aid for FeLV and/or FIV infections.
s, an aggressive tumour, at the injection site. The development of sarcomas with the use of the old FeLV and other vaccines may be due to the inflammation caused by aluminium
adjuvants
in the vaccines. It is worth noting that no causal link has been demonstrated between sarcomas and vaccination, that no statistical difference has been shown between prevalence of Sarcomas in those animals vaccinated with adjuvented or unadjuvented vaccines, and that the occurrence of sarcomas is significantly lower in Europe and Great Britain than the USA regardless of the use of similar vaccines.
Merial
produces a recombinant
vaccine consisting of canarypox virus carrying FeLV gag and env genes (sold as PUREVAX FeLV in the USA and Eurifel FeLV in Europe). This is thought to be safer than the old vaccine as it does not require an adjuvant to be effective. Although this is a live virus, it originates from a bird host and so does not replicate in mammals. However, it has not been shown to reduce the incidence of sarcomas in any clinical or field study.
Since the virus is very weak and dies within two hours in a dry environment, the incidence of transmission will drop considerably if the litterbox is kept from remaining damp between uses. One method is to clean all damp litter out of a standard box after each use; however, this is sometimes not practical.
Another option is a specialized three-part litterbox that uses either a ground corncob or safflower seed litter in a slotted top unit, which allows the liquid to drain into a reservoir that is emptied regularly. The litter material air-dries quickly, thus killing the virus quickly.
This litterbox was originally designed for diabetic cats, to allow regular testing of the sugar level in the cat's system. By coincidence, the box also helps prevent FeLV infection between household cats .
or oncornavirus first described by W. Jarrett (et al., Nature 202:566) at University of Glasgow
, School Veterinary Medicine, in 1964. The virus
comprises 5' and 3' LTRs and three genes: Gag (structural), Pol (enzymes) and Env (envelope and transmembrane); the total genome
is about 9,600 base pairs.
See the entry on retrovirus
es for more details on the life cycle of FeLV.
In 2006, the United States Department of Agriculture
issued a conditional license for a new treatment aid termed Lymphocyte T-Cell Immune Modulator
. Lymphocyte T-Cell Immune Modulator is by T-Cyte Therapeutics, Inc.
Lymphocyte T-Cell Immune Modulator is intended as an aid in the treatment of cats infected with feline leukemia virus (FeLV) and/or feline immunodeficiency virus
(FIV), and the associated symptoms of lymphocytopenia
, opportunistic infection
, anemia
, granulocytopenia, or thrombocytopenia
. The absence of any observed adverse events in several animal species suggests that the product has a very low toxicity profile.
Lymphocyte T-Cell Immune Modulator is a potent regulator of CD-4 lymphocyte
production and function. It has been shown to increase lymphocyte numbers and Interleukin 2
production in animals.
Lymphocyte T-Cell Immune Modulator is a single chain polypeptide. It is a strongly cationic glycoprotein
, and is purified with cation exchange resin. Purification of protein from bovine-derived stromal cell
supernatants produces a substantially homogeneous factor, free of extraneous materials. The bovine protein is homologous with other mammalian species and is a homogeneous 50 kDa glycoprotein with an isoelectric point of 6.5. The protein is prepared in a lyophilized 1 microgram dose. Reconstitution in sterile diluent produces a solution for subcutaneous injection.
The drug is quite expensive, dosage being dependent on body-weight, but will be covered by most pet insurers.
are in the same family, and are sometimes mistaken for one another. However, the viruses differ in many ways. Their shapes are quite different: FeLV is more circular while FIV is elongated. The two viruses are also quite different genetically, and their protein coats differ in size and composition. Although many of the diseases caused by FeLV and FIV are similar, the specific ways in which they are caused also differs. Also, while the feline leukemia virus typically causes symptomatic illness in an infected cat, an FIV infected cat can remain completely asymptomatic its entire lifetime.
Retrovirus
A retrovirus is an RNA virus that is duplicated in a host cell using the reverse transcriptase enzyme to produce DNA from its RNA genome. The DNA is then incorporated into the host's genome by an integrase enzyme. The virus thereafter replicates as part of the host cell's DNA...
that infects cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s. FeLV can be transmitted between infected cats when the transfer of saliva or nasal secretions is involved. If not defeated by the animal’s immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
, the virus can be lethal. The disease caused by this virus is a form of cancer of the blood cells called lymphocytes (a leukemia
Leukemia
Leukemia or leukaemia is a type of cancer of the blood or bone marrow characterized by an abnormal increase of immature white blood cells called "blasts". Leukemia is a broad term covering a spectrum of diseases...
).
Signs and symptoms
The signs and symptoms of infection with feline leukemia virus are quite varied and include loss of appetite, poor coat condition, infections of the skin, bladder and respiratory tract, oral disease, seizures, lymphadenopathyLymphadenopathy
Lymphadenopathy is a term meaning "disease of the lymph nodes." It is, however, almost synonymously used with "swollen/enlarged lymph nodes". It could be due to infection, auto-immune disease, or malignancy....
(swollen lymph nodes), skin lesions, fatigue, fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
, weight loss
Weight loss
Weight loss, in the context of medicine, health or physical fitness, is a reduction of the total body mass, due to a mean loss of fluid, body fat or adipose tissue and/or lean mass, namely bone mineral deposits, muscle, tendon and other connective tissue...
, stomatitis
Stomatitis
Stomatitis is an inflammation of the mucous lining of any of the structures in the mouth, which may involve the cheeks, gums, tongue, lips, throat, and roof or floor of the mouth...
, gingivitis
Gingivitis
Gingivitis is a term used to describe non-destructive periodontal disease. The most common form of gingivitis is in response to bacterial biofilms adherent to tooth surfaces, termed plaque-induced gingivitis, and is the most common form of periodontal disease...
, litter box avoidance, pancytopenia
Pancytopenia
Pancytopenia is a medical condition in which there is a reduction in the number of red and white blood cells, as well as platelets.If only two parameters from the full blood count are low, the term bicytopenia can be used...
, poor grooming, recurring bacterial and viral illnesses, anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
, diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, and jaundice
Jaundice
Jaundice is a yellowish pigmentation of the skin, the conjunctival membranes over the sclerae , and other mucous membranes caused by hyperbilirubinemia . This hyperbilirubinemia subsequently causes increased levels of bilirubin in the extracellular fluid...
.
Transmission
CatCat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s infected with FeLV can serve as sources of infection. Transmission is related to the subgroup (see below). Cats can possibly pass the virus between themselves through saliva and close contact, by biting another cat, through a litter box or food dish used by an infected cat (rarely happens), and from milk during nursing. Transmission can also take place from an infected mother cat to her kittens, either before they are born or while they are nursing.
Initially thought to survive only about 2 hours in a dry environment, and about 48 hours in a damp environment (such as a litter box) a new paper published by Cornell vets (http://www.vet.cornell.edu/FHC/news/) titled "Can FeLV survive in the environment?" likened FeLV to HIV (which can survive for several weeks in the environment and is structurally related to FeLV). In the absence of any meaningful studies in to the survival of FeLV in the environment, it may be sensible to exercise caution when assuming FeLV survival in the environment is so short (2 hours to 2 days).
FeLV causes immunosuppression
Immunosuppression
Immunosuppression involves an act that reduces the activation or efficacy of the immune system. Some portions of the immune system itself have immuno-suppressive effects on other parts of the immune system, and immunosuppression may occur as an adverse reaction to treatment of other...
in pet cats, and there is also evidence for existence of the virus in larger wild cat populations also (e.g. lynx
Lynx
A lynx is any of the four Lynx genus species of medium-sized wildcats. The name "lynx" originated in Middle English via Latin from Greek word "λύγξ", derived from the Indo-European root "*leuk-", meaning "light, brightness", in reference to the luminescence of its reflective eyes...
, cheetah
Cheetah
The cheetah is a large-sized feline inhabiting most of Africa and parts of the Middle East. The cheetah is the only extant member of the genus Acinonyx, most notable for modifications in the species' paws...
s, and lion
Lion
The lion is one of the four big cats in the genus Panthera, and a member of the family Felidae. With some males exceeding 250 kg in weight, it is the second-largest living cat after the tiger...
s). Overwhelming epidemiologic
Epidemiology
Epidemiology is the study of health-event, health-characteristic, or health-determinant patterns in a population. It is the cornerstone method of public health research, and helps inform policy decisions and evidence-based medicine by identifying risk factors for disease and targets for preventive...
evidence suggests FeLV is not transmissible to either humans or dogs. This statement is based on the fact that approximately one pet dog in five lives with a cat, and all pet cats live with humans (some 60 million pet cats in the USA). It is species-specific, and does not infect other animals, such as dogs (in fact, there is apparently no canine version of this disease at all).
Approximately 0.5% of pet cats are persistently infected with FeLV, but many more pet cats (>35%) have specific IgG antibodies which indicate prior exposure and subsequent development of immunity instead of infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
. Transmission of FeLV is mainly via saliva
Saliva
Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...
and friendly behaviors, such as sharing feeding bowls and mutual grooming (as distinct from fighting and biting).
There is strong evidence kittens under 4 months of age are susceptible to infection, but by 8 months are resistant to it.
Kittens can be born with it, having contracted it from their mother while in utero.
Infection is far higher in city cats, stray or owned, than in rural cats: this is entirely due to the amount of contact the cats have with each other.
Four subgroups of FeLV exist: A; B; C, and T, but only subgroup A is transmissible between cats. The other subgroups arise de novo and as results of recombination
Genetic recombination
Genetic recombination is a process by which a molecule of nucleic acid is broken and then joined to a different one. Recombination can occur between similar molecules of DNA, as in homologous recombination, or dissimilar molecules, as in non-homologous end joining. Recombination is a common method...
with an endogenous DNA feline sequence. Hence, there is very good evidence this virus is quite ancient, and may well have evolved more than one time over the last 10,000,000 years.
Subgroups are defined on the basis of viral interference and in vitro host range. The differences are due to polymorphism in the envelope glycoprotein gp70 with the highest level of divergence lying in the region of gp70 which is thought to interact with the cellular receptor. In an infected cell, gp70 is thought to block viral receptors, so preventing further infection by the same subgroup.
Progression
The disease has a wide range of effects. The cat can fight off the infection and become totally immune, can become a healthy carrier that never gets sick itself but can infect other cats, or a mid-level case in which the cat has a compromised immune system. Nevertheless, the development of lymphomas is considered the final stage of the disease. Although it is thought that virus protein has to be present to induce lymphomas in cats, newer evidence shows that a high percentage of FeLV-Antigen negative lymphomas contain FeLV-DNA, indicating a "hit-and-run" mechanism of virus induced tumor development.Once the virus has entered the cat, there are six phases to a FeLV infection:
- Phase One: The virus enters the cat, usually through the pharynx where it infects the epithelial cells and infects the tonsorial B-lymphocytes and macrophages. These white blood cells then filter down to the lymph nodes and begin to replicate.
- Phase Two: The virus enters the blood stream and begins to distribute throughout the body.
- Phase Three: The lymphoid system (which produces antibodies to attack infected and cancerous cells) becomes infected, with further distribution throughout the body.
- Phase Four: The main point in the infection- where the virus can take over the body's immune system and cause viremia. During this phase the hemolymphatic system and intestines become infected.
If the cat's immune system does not fight off the virus, then it goes onto:
- Phase Five: The bone marrowBone marrowBone marrow is the flexible tissue found in the interior of bones. In humans, bone marrow in large bones produces new blood cells. On average, bone marrow constitutes 4% of the total body mass of humans; in adults weighing 65 kg , bone marrow accounts for approximately 2.6 kg...
becomes infected. At this point, the virus will stay with the cat for the rest of its life. In this phase, the virus replicates and is released four to seven days later in infected neutrophils (white blood cellWhite blood cellWhite blood cells, or leukocytes , are cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a...
s), and sometimes lymphocytes, monocytes (white blood cell formed in the bone marrow), and eosinophils (another white blood cell).
- Phase Six: The cat's body is overwhelmed by infection and mucosal and glandular epithelial cells (tissue that forms a thin protective layer on exposed bodily surfaces and forms the lining of internal cavities, ducts, and organs) become infected. The virus replicates in epithelial tissues including salivary glands, oropharynx, stomach, esophagus, intestines, trachea, nasopharynx, renal tubules, bladder, pancreas, alveolar ducts, and sebaceous ducts from the muzzle.
Cats diagnosed as persistently infected by ELISA
ELISA
Enzyme-linked immunosorbent assay , is a popular format of a "wet-lab" type analytic biochemistry assay that uses one sub-type of heterogeneous, solid-phase enzyme immunoassay to detect the presence of a substance in a liquid sample."Wet lab" analytic biochemistry assays involves detection of an...
testing may die within a few months or may remain asymptomatic for longer. The fatal diseases are leukemias, lymphomas
Lymphoma in animals
Lymphoma in animals is a type of cancer defined by a proliferation of malignant lymphocytes within solid organs such as the lymph nodes, bone marrow, liver and spleen. The disease also may occur in the eye, skin, and gastrointestinal tract. It is also known as lymphosarcoma.-Lymphoma in...
, and non-regenerative anemias. Although there is no known cure for the virus infection, in 2006 the United States Department of Agriculture approved Lymphocyte T-Cell Immunomodulator as a treatment aid for FeLV and/or FIV infections.
Prevention
Vaccines for FeLV are available (ATCvet code and various combination vaccines), though no currently available vaccine offers 100% protection from the virus. Serious side effects have also been reported as a result of FeLV vaccination; in particular, a small percentage of cats who received FeLV vaccines subsequently developed vaccine-associated sarcomaVaccine-associated sarcoma
A vaccine-associated sarcoma is a type of malignant tumor found in cats that has been linked to certain vaccines. VAS has become a concern for veterinarians and cat owners alike and has resulted in changes in recommended vaccine protocols...
s, an aggressive tumour, at the injection site. The development of sarcomas with the use of the old FeLV and other vaccines may be due to the inflammation caused by aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
adjuvants
Immunologic adjuvant
In immunology, an adjuvant is an agent that may stimulate the immune system and increase the response to a vaccine, without having any specific antigenic effect in itself. The word “adjuvant” comes from the Latin word adiuvare, meaning to help or aid...
in the vaccines. It is worth noting that no causal link has been demonstrated between sarcomas and vaccination, that no statistical difference has been shown between prevalence of Sarcomas in those animals vaccinated with adjuvented or unadjuvented vaccines, and that the occurrence of sarcomas is significantly lower in Europe and Great Britain than the USA regardless of the use of similar vaccines.
Merial
Merial
Merial is a multinational animal health company. It was formed as a joint venture between Merck & Co. and Sanofi-Aventis in 1997. Merial is now the animal health subsidiary of Sanofi-Aventis. Merial is a company leader in innovation, and provides an ample range with products to improve the...
produces a recombinant
Recombinant DNA
Recombinant DNA molecules are DNA sequences that result from the use of laboratory methods to bring together genetic material from multiple sources, creating sequences that would not otherwise be found in biological organisms...
vaccine consisting of canarypox virus carrying FeLV gag and env genes (sold as PUREVAX FeLV in the USA and Eurifel FeLV in Europe). This is thought to be safer than the old vaccine as it does not require an adjuvant to be effective. Although this is a live virus, it originates from a bird host and so does not replicate in mammals. However, it has not been shown to reduce the incidence of sarcomas in any clinical or field study.
Since the virus is very weak and dies within two hours in a dry environment, the incidence of transmission will drop considerably if the litterbox is kept from remaining damp between uses. One method is to clean all damp litter out of a standard box after each use; however, this is sometimes not practical.
Another option is a specialized three-part litterbox that uses either a ground corncob or safflower seed litter in a slotted top unit, which allows the liquid to drain into a reservoir that is emptied regularly. The litter material air-dries quickly, thus killing the virus quickly.
This litterbox was originally designed for diabetic cats, to allow regular testing of the sugar level in the cat's system. By coincidence, the box also helps prevent FeLV infection between household cats .
Viral structure
Feline Leukemia Virus (FeLV) is an RNA retrovirusRetrovirus
A retrovirus is an RNA virus that is duplicated in a host cell using the reverse transcriptase enzyme to produce DNA from its RNA genome. The DNA is then incorporated into the host's genome by an integrase enzyme. The virus thereafter replicates as part of the host cell's DNA...
or oncornavirus first described by W. Jarrett (et al., Nature 202:566) at University of Glasgow
University of Glasgow
The University of Glasgow is the fourth-oldest university in the English-speaking world and one of Scotland's four ancient universities. Located in Glasgow, the university was founded in 1451 and is presently one of seventeen British higher education institutions ranked amongst the top 100 of the...
, School Veterinary Medicine, in 1964. The virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
comprises 5' and 3' LTRs and three genes: Gag (structural), Pol (enzymes) and Env (envelope and transmembrane); the total genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
is about 9,600 base pairs.
See the entry on retrovirus
Retrovirus
A retrovirus is an RNA virus that is duplicated in a host cell using the reverse transcriptase enzyme to produce DNA from its RNA genome. The DNA is then incorporated into the host's genome by an integrase enzyme. The virus thereafter replicates as part of the host cell's DNA...
es for more details on the life cycle of FeLV.
Approved US Treatment
The first vaccine for FeLV became available in 1985.In 2006, the United States Department of Agriculture
United States Department of Agriculture
The United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
issued a conditional license for a new treatment aid termed Lymphocyte T-Cell Immune Modulator
Lymphocyte T-Cell Immune Modulator
Lymphocyte T-Cell Immune Modulator is an immune regulating polypeptide manufactured by T-Cyte Therapeutics and distributed by . Lymphocyte T-Cell Immune Modulator is a potent regulator of CD-4 lymphocyte production and function. It has been shown to increase lymphocyte numbers and Interleukin-2 ...
. Lymphocyte T-Cell Immune Modulator is by T-Cyte Therapeutics, Inc.
Lymphocyte T-Cell Immune Modulator is intended as an aid in the treatment of cats infected with feline leukemia virus (FeLV) and/or feline immunodeficiency virus
Feline immunodeficiency virus
Feline immunodeficiency virus is a lentivirus that affects domesticated housecats worldwide and is the causative agent of feline AIDS. From 2.5% up to 4.4% of cats worldwide are infected with FIV...
(FIV), and the associated symptoms of lymphocytopenia
Lymphocytopenia
Lymphocytopenia, or lymphopenia, is the condition of having an abnormally low level of lymphocytes in the blood. Lymphocytes are a white blood cell with important functions in the immune system...
, opportunistic infection
Opportunistic infection
An opportunistic infection is an infection caused by pathogens, particularly opportunistic pathogens—those that take advantage of certain situations—such as bacterial, viral, fungal or protozoan infections that usually do not cause disease in a healthy host, one with a healthy immune system...
, anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
, granulocytopenia, or thrombocytopenia
Thrombocytopenia
Thrombocytopenia is a relative decrease of platelets in blood.A normal human platelet count ranges from 150,000 to 450,000 platelets per microliter of blood. These limits are determined by the 2.5th lower and upper percentile, so values outside this range do not necessarily indicate disease...
. The absence of any observed adverse events in several animal species suggests that the product has a very low toxicity profile.
Lymphocyte T-Cell Immune Modulator is a potent regulator of CD-4 lymphocyte
Lymphocyte
A lymphocyte is a type of white blood cell in the vertebrate immune system.Under the microscope, lymphocytes can be divided into large lymphocytes and small lymphocytes. Large granular lymphocytes include natural killer cells...
production and function. It has been shown to increase lymphocyte numbers and Interleukin 2
Interleukin 2
Interleukin-2 is an interleukin, a type of cytokine immune system signaling molecule, which is a leukocytotrophic hormone that is instrumental in the body's natural response to microbial infection and in discriminating between foreign and self...
production in animals.
Lymphocyte T-Cell Immune Modulator is a single chain polypeptide. It is a strongly cationic glycoprotein
Glycoprotein
Glycoproteins are proteins that contain oligosaccharide chains covalently attached to polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. In proteins that have segments extending...
, and is purified with cation exchange resin. Purification of protein from bovine-derived stromal cell
Stromal cell
In cell biology, stromal cells are connective tissue cells of any organ, for example in the uterine mucosa , prostate, bone marrow, and the ovary. They are cells that support the function of the parenchymal cells of that organ...
supernatants produces a substantially homogeneous factor, free of extraneous materials. The bovine protein is homologous with other mammalian species and is a homogeneous 50 kDa glycoprotein with an isoelectric point of 6.5. The protein is prepared in a lyophilized 1 microgram dose. Reconstitution in sterile diluent produces a solution for subcutaneous injection.
Approved European treatment
Interferon-ω (omega) is sold in Europe at least under the name Virbagen Omega and manufactured by Virbac. When used in treatment of cats infected with FeLV in non-terminal clinical stages (over the age of 9 weeks) there have been substantial improvements in mortality rates; in non-anemic cats, mortality rate of 50% was reduced by approximately 20% following treatment.The drug is quite expensive, dosage being dependent on body-weight, but will be covered by most pet insurers.
Comparison with FIV
FeLV and Feline immunodeficiency virusFeline immunodeficiency virus
Feline immunodeficiency virus is a lentivirus that affects domesticated housecats worldwide and is the causative agent of feline AIDS. From 2.5% up to 4.4% of cats worldwide are infected with FIV...
are in the same family, and are sometimes mistaken for one another. However, the viruses differ in many ways. Their shapes are quite different: FeLV is more circular while FIV is elongated. The two viruses are also quite different genetically, and their protein coats differ in size and composition. Although many of the diseases caused by FeLV and FIV are similar, the specific ways in which they are caused also differs. Also, while the feline leukemia virus typically causes symptomatic illness in an infected cat, an FIV infected cat can remain completely asymptomatic its entire lifetime.