Pigeon Pox Virus: a Holistic Study and Its Comparison with Fowl Pox

INTERNATIONAL JOURNAL OF ANIMAL AND VETERINARY SCIENCES Journal homepage: www.jakraya.com/journal/ijavs

MINI-REVIEW Pigeon Pox Virus: A Holistic Study and Its Comparison with Fowl Pox

Pallabi Ghosh 1, Nandani Kumari 2* and Saurabh Karunamay 3

1B.V.Sc and A.H Scholar, 2* Assistant Professor, Department of Animal Genetics and Breeding, Ranchi Veterinary College, B.A.U, Ranchi, Jharkhand, India. 3Assistant Professor, Department of Livestock Products Technology, FVAS, I.Ag.Sc., R.G.S.C, Banaras Hindu University, Mirzapur, Uttar Pradesh, India.

Abstract Recently Pigeon pox grabbed headlines due to probable reporting of *Corresponding Author: mortality in India at several places in pigeons due to Pigeon pox virus .

NandaniKumari Reports suggest the specificity of host of Pigeon pox and Fowl pox thus Email: [email protected] pigeon pox virus affects pigeons and Fowl pox virus affects a very different host range. Current study deals with the detailed coverage of pigeon pox Received: 19/09/2020 with relevance to clinician point of view. It also compares Pigeon Pox with Accepted: 27/11/2020 Fowl pox.

Keywords: Pigeon pox virus, Host range, Specificity, Clinical symptoms.

1. Introduction 3. Structure and Virology of Pigeon Pox Poxviridae is a family of viruses which infect Virus humans, vertebrates, and arthropods as its natural hosts. Pigeon pox virus is an enveloped, brick shaped This family has a total of 69 species divided into 28 virus. It has linear genomic arrangement and genera which is further subdivided into two subfamilies monopartite genomic segmentation. They are unique in (https://en.wikipedia.org/wiki/Poxviridae). In humans, several aspects, and have been rightly described as chicken pox is caused by Herpes virus, Variola major successful pathogens. There are many reasons for it. and Variola minor isolates of the pox virus species. Most important of them being that firstly because of Variola virus was the cause of smallpox, which was cytoplasmic site of virus replication, they are able to declared eradicated worldwide in 1980 by the World encode many enzymes required for macromolecular Health Organization precursor and for biosynthetic processes. Secondly as (https://www.britannica.com/science/poxvirus). Pigeon they have complex morphogenesis involving the de- pox is caused by Pigeon pox virus of genus novo synthesis of virus-specific membranes and Avipoxvirus of the Chordopoxvirinae subfamily and inclusion bodies and also because the genomes of these Poxviridae family causing the formation of dry crusty viruses encode several proteins which interact with host vesicles on the skin of pigeons (cutaneous pox) and processes at both the cellular and systemic levels yellow ‘cheesy’ plaques in the mouth (mucosal pox). (Hermosa and Ricardo, 2001). Generally the disease is considered as a mild one, with the birds usually displaying mild or no signs of 4. Host Specificity systemic disease. Except for some strains which cause The most important finding of Siddique et al. severe tissue damage, deformity of eyelids, and or (2011) was that both PPV and FPV had host specificity. tongue loss of sections or the entire beak, generally the The results of the investigation were in agreement with majority of strains cause mild symptoms. It must be the findings of Cunningham (1966, 1972); Tripathy and mentioned here that there have been found a number of Cunningham (1984) who described that Pigeon pox and strains associated with Pigeon pox virus and generally Fowl pox viruses are host specific and produced disease the strain which escape vaccine formation or the in their respective hosts only. Zoonotic importance- vaccine formed might be responsible for the pox Pigeon pox is non-zoonotic in nature, i.e. it is not lesions. So in majority of cases pigeon pox is a disease transmitted to human being. of inconvenience rather the loss of bird due to very minimal rate of mortality associated with it 5. Pathogenesis (https://www.auspigeonco.com.au/pox-virus.html). After transmission either directly while fighting, feather picking or indirectly by mosquito bites or other 2. Etiology biting and sucking insects like pigeon louse flies or There are two forms of the disease, the mites. Then the virus enters the body through mucous cutaneous form is usually caused by mosquito bite and membranes or wound to the skin. There is an the diphtheritic form or the wet form is due to aerosol incubation period of 7 to 9 days. There are 2 forms in or droplet infection. which this disease exists-one is cutaneous and other diphtheritic form. In the cutaneous form scattered

multifocal dry-discrete scabby lesions are formed on with distilled water also twice daily ½ teaspoonful of the unfeathered parts of the body especially beak and the mixture was fed to pigeon orally. eyelids. The bird may be unable to open the eyelids and there may yellowish cheesy material surrounding the 8.2 Cutaneous Form eyes. In the diphtheritic form multiple yellowish According to Sudhakara and Sivajothi (2017), nodules or fibronecrotic wet lesions were seen on the Azithromycin was effective in the treatment of the mucosa of pharynx, larynx and mouth. Usually the cutaneous form when given at the dose rate 20mg/kg lesions heals in 3 - 4 weeks but the diphtheritic lesions body weight orally b.i.d. along-with oral multi-vitamin may persist for months (Audarya et al., 2018). Since it supplementation syrup, liver tonic for two weeks and is a self-limiting disease scabs are shed but poxviruses skin lesions were applied with povidone iodine are present in the scabs and because they are resistant ointment. Disappearance of the skin lesions marked the to drying, remain stable in the environment. At times, improving clinical condition and after 10 to 12 days of because of secondary bacterial infection it may therapy scab and complete remission of the cutaneous interfere with other body functions. Also, when scabs lesions was noticed. Antibiotics are usually prescribed are removed forcibly it may result in bleeding and by the vet to ensure prevention of secondary infections. deformity. Mortality rate is higher in diphtheritic form Vitamin A can come to the aid for skin healing if lesions appear in the mouth. (Pigeon-aid, UK).

6. Microscopic Finding 9. Prevention Nodular lesions on the showed areas of necrosis If a pigeon is infected it should be isolated in with infiltrating inflammatory cells. Epidermal cells order to prevent direct transmission or indirect had hydrophic degeneration which was characterized transmission by mosquitoes and other biting and by vacuolation of the cytoplasm (Pledger, 2005). sucking insects like pigeon louse flies or mites. Epidermal hyperplasia was seen which may be due to Immunization by vaccination is practically the best the localized production of vaccinia growth factor method. A live viral vaccine with ATCvet code: (VGF) that binds to the epidermal growth factor QI01ED01 (WHO) is available. The two basic methods receptors of epithelial cells (Moss, 1990). Large, round, of vaccine application are: intra-cytoplasmic eosinophilic inclusion bodies called One is scratch method in which with the help of Bollinger bodies are seen within the epithelial cells a hypodermic needle that is dipped into the vaccine which are considered to be the location of replication of followed by one or two scratches in the skin of the the virus particle (Murphy et al., 1999). breast. Some skill is required in this method, if the scratch is too superficial then no local lesion will 7. Clinical Finding develop and if it is too deep then fair amount of blood In cutaneous form there are dry discrete grayish will exude and the vaccine will be flushed out. In the white nodules in the featherless parts of the body, absence of a local lesion there is no certainty that the nodules near the eye may affect the vision which may pigeon will develop immunity. affect their ability to reach feed and water thus leading The second method is the “follicle method”, this to starvation and ultimately death. Yellowish cheesy is the most effective method. In this method, material may be seen surrounding the eyes. Nodules are approximately five feathers are plucked out on the gradually self-limiting and gradually form scab and lower leg and the vaccine is applied by means of a shed off. In diphtheritic form initially small nodules are brush dipped into the vaccine. Follicular lesions come formed on the mucous membrane of mouth, pharynx, up within 7-10 days and although the lesions may look larynx which later on may interfere with feeding and unsightly for a couple of days and then they completely breathing. The mortality rate is much higher in disappear after 2-3 weeks. The general health of such diphtheritic form. The birds are found poor in health vaccinated pigeons is not affected but the resultant and emaciated. immunity is of high quality and good duration. Subcutaneous injection may be given at the dose rate 8. Treatment 0.2 ml per pigeon dorsally in the neck towards the Being a viral disease, symptomatic treatment is direction of the tail but not immediately behind the given in this case. Broad spectrum antibiotic is given to head. prevent secondary bacterial infection. Note- At four weeks of age or older, young birds should be vaccinated, but at least 4 weeks before they 8.1 Diphtheritic Form are exposed to other pigeons (before racing or Jan et al. (2017) stated that when the pigeon was showing). All susceptible birds in the lot should be treated with crushed garlic ( Allium sativum ) mixed with vaccinated at the same time. Maximum protection takes honey at 1:1 ratio for 7 days. Post three days of 3 to 4 weeks while the duration of the immunity is not treatment the pigeon showed recovery from lesion on permanent, birds should be revaccinated annually mouth then the lesions around eyes and lesion on beak (https://www.drugs.com/vet/avipro-pigeon-pox- were last to recover. The mixture was applied on p.html). topically on the lesion and washed after 20 minutes

Table 1: Vaccination chart for pigeon pox relatively resistant to the common disinfecting methods. During an outbreak the affected birds should Adult 5 weeks before mating (follicle be segregated if the number is under control and the Pigeons method) remaining birds in the flock should be vaccinated 3 weeks before mating immediately. (subcutaneous injection) Young 9th week of age (follicle method 12. Comparison with Fowl Pox Pigeons or subcutaneous method) Experimental infection in pigeons with the 10. Diagnosis pigeon pox virus produced moderate infection as compared to the diseased birds, while in chicken the Gross lesions are usually sufficient to suspect virus produces mild infection (Ramzi, 2018). On the both the cutaneous and diphtheritic forms of pox other hand Fowl Pox is a disease predominantly of infection (Tripathy and Reed, 2003). Confirmatory poultry. In India fowl pox vaccine is produced but no diagnosis is usually done by histopathological such vaccine is produced for Pigeon pox. Pigeon pox examinations and demonstration of Bollinger bodies in vaccine that is chicken embryo propagated is available the cells. Histopathological examinations are carried for immunization in chickens but not for pigeons. out of the cutaneous nodules which reveal the presence Pigeon pox vaccine is used against fowl pox in of intracytoplasmic inclusion bodies in the cells. chickens because they are less pathogenic. Non- Molecular characterization of the virus may be done by attenuated viruses are used to control Fowl pox in using PCR and real-time PCR techniques. Indirect chickens. On the other hand, based on the findings of immune-fluorescent and indirect immunoperoxidase Singh et al. (2003), in his work, he generated tests are some other tests that may be used for diagnosis monoclonal antibodies against two distinct Fowl pox of the virus. Electron microscopy can be used by virus proteins. The feasibility of using 2 MAbs to negative staining method or in ultrathin sections of identify and characterize Fowl pox virus strains as well infected tissues to demonstrate (Doaneand Anderson, as to differentiate them from other Avipoxviruses was 1987). The virus grows well in chorioallantoic evaluated. A simple immuno-dot blot assay for membrane of chick embryos of 11-12 days old, and detection of FPV antigens in lesion samples was produced typical pock lesions (Al-Ageleand Ramzi, initially developed for this purpose. Immuno-blotting 2018). Molecular method of diagnosis-according to was eventually used to explore the variation in the size Audarya et al. (2018), June 2017, a Pigeon showing of a virus-encoded protein identified by one of the clinical lesions of yellowish crust/nodules on and MAbs. Thus it was observed that there is 100% around beak and eyes and feet was observed in a homology between comparative Pigeon pox and Fowl scattered group of around 40 pigeons. After processing pox virus entries in GenBank, and both MAbs used in of clinical specimen the inoculums were inoculated into this study react with similar-sized proteins in both chicken embryonated eggs by using chorioallantoic viruses. So he further found out it might be possible membrane route. Viral deoxyribonucleic acid was that these 2 viruses namely FPV and Pigeon pox extracted and used in Avipox virus specific polymerase presumably represent one virus that has been isolated chain reaction. No specific lesions were observed in from two different bird species. inoculated chicken embryonated egg even after third passage. However, in polymerase chain reaction 13. Conclusion Avipox virus specific P4b gene (578 bp) was Pigeon pox mostly is a mild disease; it is more successfully amplified and visualized in 1% agarose gel of a disease of inconvenience because of the low rate of on electrophoresis. This proves the greater efficacy of mortality. Only some strains that cause severe harm molecular methods in confirmatory diagnosis of pigeon may cause death of the pigeon. The rate of mortality is pox virus/avian pox disease. more in diphtheritic form because it affects the 11. Current Concern systemic parts, on contrary to cutaneous form which forms lesion on the body surface. The cutaneous forms The disease is frequently observed during rainy are dry in nature and during recovery forms scab while and winter seasons with persisting overcrowding and diphtheritic forms being on mucosal surface have unhygienic condition. If a bird is affected it quickly cheesy plaques. Vaccination is the best method of spreads to other birds in flocks. Once a pigeon is prevention in big herds. Treatment is symptomatic and affected it remains a problem for a long time in the usually recovery is achieved, in cutaneous form flock since the virus belongs to Avipoxvirus, which can recovery is seen within 10-12 days. live in the dried scabs for several years and are also

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