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Chinese Hamster serves as SARS-CoV-2 infection model

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Chinese Hamster serves as SARS-CoV-2 infection model

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The uncontrollable worldwide spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has urged testing of prophylactic and therapeutic measures. Several SARS-CoV-2 animal models have been investigated, including non-human primates, ferrets, transgenic mice, cats and hamsters. The study was carried out to determine SARS-CoV-2 susceptibility to Chinese hamster (Cricetulus griseus) and establish this species as novel small animal model for SARS-CoV-2 research.

Compared to Syrian hamster, transient but significant body weight loss and subtle drops in body temperatures at early time points after infection. Also, the course of bronchitis and pneumonia was milder than in Syrian hamsters but pneumonia was more prolonged in Chinese hamster. Taken together, the results suggested the suitability of Chinese hamster, the small animal model to study SARS-CoV-2 infections with prolonged period of significantly reduced body weights as a robust clinical disease parameter. Moreover, the considerably smaller size of the Chinese hamster offers an important practical advantage which allows allows husbandry in smaller cages and larger groups compared to the rather large Syrian hamster (Bertzbach et al, 2021).

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Syrian Hamster acts as an animal model for Oral Carcinogenesis

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Syrian Hamster acts as an animal model for Oral Carcinogenesis

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The Syrian hamster cheek-pouch carcinogenesis model is one of the most accepted animal models to study oral tumor formation and progression as they have human skin-like characteristics.

To study the tumor formation, carcinogens, 7,12-dimethylbenz(a)anthracene  (DMBA) was administered repeatedly by topical application to the buccal pouch which would then induce carcinomas rapidly. This administration technique involves anesthetizing the hamster and brushing the desired carcinogens onto the buccal surface of the cheek pouch.

A key advantage of the hamster cheek pouch carcinogenesis is the predictable nature of tumor progression. Also, the cellular and molecular alterations in the hamster display many similarities to human oral squamous cell carcinoma (OSCC). A recent study has shown that it is possible to isolate the buccal pouch stem cells which can be studied in vitro and may provide data on novel treatment (Vairaktaris et al., 2009).

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A number of studies have proved that clinical symptoms shown by Syrian hamster are similar to that of symptoms developed after human infection. Moreover, compared to other animal models, the Syrian hamster immune response is more physiological similar to human immune response. Therefore, this animal models do contribute enormously to our understanding of infectious diseases and also demonstrates the strong potential for future research and development of antiviral and antibacterial drug discovery.

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Syrian Hamster as an Animal Model for the Study on Infectious Diseases

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Infectious diseases still remain one of the biggest challenges for human health. In order to gain a better understanding of the pathogenesis of infectious diseases and develop effective diagnostic tools, therapeutic agents, and preventive vaccines, a suitable animal model which can represent the cha…

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Syrian Hamster used for Research in Bacterial and Parasitic Infections

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Syrian Hamster used for Research in Bacterial and Parasitic Infections

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Other than viral infection, Syrian hamster is also an ideal animal model for the study of a series of human bacterial and parasite infections. For example, pathogens like Clostridium difficile, Entamoeba histolytica, Babesia and Helicobacter spp. have been studied by researchers.

The use of mouse animal model is unable to provide Clostridium difficile infection (CDI) drug discoveries, so Syrian hamster is used in the following study. Several studies have shown that CDI-infected hamsters developed many of clinical symptoms observed in infected humans. The efficacy of antibiotic against Clostridium difficile such as LFF571 was also assessed using Syrian hamster as their animal model.

The Syrian hamster is highly susceptible to visceral Leishmania species, thus it is considered the best experimental model to study visceral leishmaniasis (VL) as it reproduces the clinicopathological features of human disease and quite distinct from those noted in murine models of infection (Miao, Chard, Wang, & Wang, 2019)。

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Besides studying the pathogenesis of the viral infection, Syrian hamster also serves as animal model for validating antiviral drugs and antiviral therapies. Recent findings have shown that treatment with the antiviral compounds 2'-C-methyl cytidine, T-1106, IFN alfacon-1, and BCX4430 pre- and post-YFV exposure can significantly improve Yellow Fever virus-infected Syrian hamster survival (Widman et al., 2009). Furthermore, in a recent study, the results of Ebola virus infection in hamsters demonstrate that CD4+ T cells are required for natural immunity and CD4-dependent antibody responses are required for immunity against the virus in this animal model (Miao, Chard, Wang, & Wang, 2019).

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Syrian Hamster used for Research in Viral Infections

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Syrian Hamster used for Research in Viral Infections

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Several studies have documented that Syrian hamsters represent better models for analysis of viral infections compared to murine models as the similarity to humas concerning disease symptoms, pathogenesis and immune responses is greater. For instance, human cytokines like granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-12 (IL-12), are fully functional in hamster models, but not in mouse models (Miao, Chard, Wang & Wang, 2019).

At present, over 70 different viruses have been investigated using Syrian hamster. In spite of this, more viral infection studies will be explored in the future. Many viruses have been studied by introducing them into Syrian hamster for research on human-associated disease such as Nipah virus, Marburg Virus, Zika virus and many more other viruses.

According to studies, infected Syrian hamsters with West-Nile virus (WNV) and Nipah virus develop neurological disease where histologic abnormalities and appearance were observed. Meanwhile, in WNV-infected immunocompromised hamsters which corresponds to immunocompromised cancer patient, the animals were shown to develop chronic viremia and sustained renal infection for 8 months. The pathology caused by Ebola virus is similar to that of humans, which includes significant spleen and liver damage, cytokine dysregulation, severe coagulopathy, lymphocyte apoptosis, and infected organ necrosis or apoptosis.

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Syrian Hamster serves as an animal model for various studies

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Syrian Hamster serves as an animal model for various studies

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The Syrian hamster(Mesocricetus auratus) has been used as an animal model to study human-associated diseases for over 60 years. Studies found out that Syrian hamster immune responses to infectious pathogens are similar to humans. Therefore, it is advantageous for studying pathogenesis of infection including post-bacterial, viral and parasitic pathogens. Also, this animal model can be used to assess the efficacy and interactions of medications and vaccines for those pathogens.

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There is a pair of flank glands at the lateral side of both female and male hamster body. These glands appear as dark spots within the hair coat.

However, the glands are much more obvious and larger in males than in females. These glands serve as “scent
marking” to establish territory and for reproductive success. They scent-mark their territory by secreting substances from the flank glands which emits an odor. Thus, the flank glands are also called as scent glands.

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The most obvious difference in adult female hamsters will be the presence of nipples on the belly. Only female Syrian hamster has 6 pairs of nipples which line up in parallel on the belly while male Syrian hamster do not have any.

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Hamsters have two openings, which are their sexual organs (vagina or penis) and their anus.

In females, the gap between the two is hardly noticeable and the area around them will be bald.

In males, however, there is a much larger gap and there is likely to be hair. Also, male hamsters have testicles but would not be observed if they are feeling cold or anxious as they retract the testicles.

Besides that, female Syrian hamsters are larger, heavier than males and generally are more aggressive than male hamsters. Non-estrous females can behave especially aggressively toward young males and may kill them.

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The easiest way to distinguish the sex of Syrian hamster is by looking at its genitalia and the anogenital distance.

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1. The respiratory system of the hamster consists of the nasal cavity, nasal sinuses, pharynx, larynx, trachea, and lungs.
2. The hamster nasal cavity consists of vestibular, olfactory, and non-olfactory portions.
3. The larynx is composed of the epiglottic, thyroid, cricoid, and arytenoid cartilage.
4. The lung lobes consist of a single lobe on the left and four lobes on the right.

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1. During pregnancy, liver weight significantly increases with a rate that is proportionately greater than the increase in body weight.
2. Increase in liver weight lead to a decrease in bile flow.
3. Compared to a non-pregnant female hamster, the mean rate of bile flow in an 8-day pregnant and a 14-day pregnant hamster is reduced by 37% and 64%, respectively.
4. In addition, a reduced secretion of total bile acids can be due to decreased cholic acid secretion, a decrease in sodium, potassium, ATPase activity and a decrease in the acid-dependent bile flow.

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1. Liver consists of 4 lobes: Right dorsocaudal, left dorsocaudal, dorsal median, and ventral median
2. Gall bladder is located in the right cranioventral section of the ventral median lobe of the liver.
3. The gall bladder wall consists of 3 major layers: mucosa, muscularis and serosa.
4. Hamster bile acids have a similar composition to human bile.

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Cheek Pouches, Liver and Gall Bladder

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1. Female hamsters with newborn pups may place the young in cheek pouches if stressed😶.
2. The pouches are emptied by a massaging action with the front feet and action of the tongue.
3. The pouches have been termed as "immunologically privileged" due to the lack of an intact lymphatic drainage system.

* The unique anatomical and physiological characteristics of the cheek pouches have contributed to their extensive use for microvascular studies of tumor growth, carcinogenesis and inflammation.

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1. Distensible
2. Well-vascularized
3. Thin-walled
4. Lined with stratified squamous epithelium
5. Devoid of lymphatic tissue
6. Rich in mast cells
7. Approximately 35-40 mm long; 4-8 mm wide when empty, up to 20mm wide when full

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This gene is sex-linked, therefore this pattern exists in female hamster only. Tortoiseshell hamsters have patches of the main color, yellow and white.

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The placing of the spots is random. Some only have a few spots, whilst others have so many spots that they appear to be joined up with very little white showing. Dominant spot hamsters often have a blaze of white up the middle of their faces. Common colors include black, yellow, cinnamon and golden.

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The most common pattern can be found in pet shops. Ideally, a banded hamster will have a perfectly straight band around the middle of the body and the width of the band will be exactly one third of the length of the body. However, in nature, the quality of a band is random.

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A roan hamster looks like a white hamster with splattered color concentrated at the head and then gradually getting lighter towards the rear. The colored parts on a roan will be lighter than the same color on a non-roan.
They will often have mottled ears and will always have a reddish glow to the eyes when light is shone on them.

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All Syrian patterns are dominant. Thus, only one copy of the gene is required to produce the pattern in pups. The Syrian hamsters exist in many patterns including roan, banded, dominant spot, and tortoise shell.

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Syrian hamster can have either short hair or long hair where the long hair gene is recessive. Length of hair in the longhaired Syrian hamster is influenced by testosterone. Thus, it is no doubt that longhaired males from the age of sexual maturity have significantly longer hair than females or castrated males, which display fluffy, shorter hair.

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All hamsters have cheek pouches, which extend along both sides of the head and neck all the way back to the shoulders. By having the cheek pouches, wild hamsters can bring food back to their burrows. This habit led to their name, which roughly translates to "mister saddlebags" in the local Arabic dialect where they are from.

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Hamsters have been used to understand circadian rhythms, chemical communication and other aspects of basic mammal biology. Because of the hamsters introduced by Arahoni are inbred, they suffer congenital heart disorders, particularly dilated cardiomyopathy. Heart disease is nearly as common in domestic hamsters as it is in humans. This particular form of dying has made them useful animal models for our own heart disease. Perhaps more so than any other species, the hamsters will die like us. For that reason, they are likely to continue to be used in labaratories  to help us understand human beings (Rob, 2011).

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At first, Arahoni placed the mother and all her pups (10) in a box. Upon being placed in a box, the mother began to eat her babies. Therefore, Arahoni decided to kill the mother hamster and so that she would not eat any more of the babies. After that, out of the nine Syrian hamster, five escaped and one was killed. The remaining three consisted of 2 females and 1 male. A single female is then placed in a special chamber and the only surviving brother was introduced to her. What happened next? The brother and sister hamsters mated.

From then on, the amount of the hamsters multiplies. That single brother and sister gave rise to 150 offspring who begat even more until there were thousands and then tens of thousands, and finally the modern multitudes of hamsters. And so it is that every domestic Syrian hamster on earth now descends from Aharoni’s first couple (Rob, 2011).

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In the spring of 1930, Israel Aharoni, a Jewish biologist working in Turkish-controlled Jerusalem staged an expedition to the hills of Syria, near Aleppo, one of the oldest cities in the world. He wanted to catch the rare golden mammal whose Arabic name translates roughly as “mister saddlebags.” One of Aharoni’s colleagues, Saul Adler, thought that the animal might be similar enough to humans to serve as a lab animal in medical research, particularly for the study of the parasitic disease leishmaniasis, which was and is still common in the region.

Aharoni had found a mother and her ten soft and young pups, which is known as Syrian hamster. It is now the most common hamster in the world, simply the hamster. Despite of studying in any great detail, Aharoni bred them so that Syrian hamster could be used as laboratory animals. In the meantime, another species of hamster was already being used for research in China. However, they would not reproduce in captivity and so had to be collected repeatedly. Aharoni thought he would be luckier with the Syrian hamster, though just why he was so optimistic is unknown (Rob, 2011).

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The Syrian hamster was first mentioned in 1797, when physician Alexander Russell came across them in the wild and described the rodents in a publication, The Natural History of Aleppo. At that time, the rodents did not have their own name. According to Peter Logsdail, a hamster expert and author of Hamster Lopaedia, it took another 40 years or so until George Robert Waterhouse, curator of the London Zoological Society, formally named the species Mesocricetus auratus, meaning Golden Hair (Christine, 2014). This is why the Syrian Hamster is commonly known as the Golden Hamster.

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1. When was the Syrian hamster first discovered?
2. Who named the hamster?
3. Why did the Syrian hamsters become laboratory animals?

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Hamster is available as outbred stock as well as inbred strain.

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Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Rodentia
Suborder: Myomorpha
Superfamily: Muroidea
Family: Cricetidae
Subfamily: Cricetinae
Genera: Allocricetulus, Cansumus, Cricetus, Cricetulus, Mesocricetus, Phodopus and Tscherskia
Species: Over 20 species. Only five species are common as pets: Syrian golden hamster (Mesocricetus auratus);  Chinese hamster (Cricetulus griseus); Campbell's or dwarf hamster (Phodopus campbelli); Djungarian or winter-white Russian dwarf hamster (Phodopus sungorus); Roborovski hamster (Phodopus roborovskii)

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Hamsters are small-sized rodents. Nowadays, they are very commonly kept as house pets. Before that, however, hamsters have been used commonly in research.

The hamster species that are ued as research models include the Syrian (golden), Mesocricetus auratus; the Chinese (striped-back), Cricetulus griseus; the Armenian (gray), C. migratorius; the European, Cricetus cricetus; and the Djungarian, Phodopus campbelli (Russian dwarf) and P. sungorus (Siberian dwarf) (Miedel & Hankenson, 2015).

Among them, hamsters especially Syrian hamster are widely used experimental animal model (Valentine, Daugherity, Singh, & Maurer, 2012).

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Outbred stocks of Armenian, Chinese and Syrian hamster

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Inbred strains of Armenian, Chinese and Syrian hamster

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1. Hamsters are nocturnal animals, which means they are active during the night and sleep during the day.
2. Some hamsters are very social, while others are loners.
3. For example, the Syrian hamster and Chinese hamster doesn't like living near other hamsters, according to the Hamster Society Singapore. They are very territorial and should never be put in a cage with other hamsters. Syrian hamster will bite the other hamster, and may even kill it.
4. Dwarf hamsters, on the other hand, are social and like to have a friend nearby.