Mycoplasma gallisepticum (MG) is a bacterium belonging to the class Mollicutes and the family Mycoplasma. It is the causative agent of chronic respiratory disease (CRD) in chickens and infectious sinusitis in turkeys, chickens, game birds, pigeons, and passerine birds of all ages. MG is transmitted through the eggs of carrier hens. Most commercial flocks are MG free, however, and the disease is most frequently introduced from carrier birds being brought into the flock. Stress is thought to lower the poults resistance to the disease, like in CRD. Symptoms of infectious sinusitis for turkeys include watery eyes and nostrils and the area under the eye may be swollen. One may find airsacculitis with yellow exudates in the air sacs. Chickens may have no outward symptoms or there may be a sticky nasal discharge, airsacculitis, coughing, difficult breathing, swelling of the face, sneezing, a foamy secretion in the eyes, and a drop in food consumption. Egg production may be far below normal and there may be a drop in body weight as well. In CRD of young poultry, symptoms include rattling, sniffling, and sneezing. In older birds, conditions may go unnoticed. Worse conditions may exhibit nasal discharge or foamy secretion from the eyes. Lack of appetite, trouble breathing and a drop in egg production are also symptoms.The birds will also be stunned and unthrifty (Wiki: Mycoplasma gallisepticum).
4. Microbial Pathogenesis
The epithelium of the upper air passages is most susceptible to infection; however, in severe, acute disease the infection is also found in the lower respiratory tract. There is a marked interaction between respiratory viruses, Escherichia coli , and M. gallisepticum in the pathogenesis of chronic respiratory disease. Once infected, birds remain carriers for life (Merck Vet Manual: M. gallisepticum).
5. Host Ranges and Animal Models
M. gallisepticum infection is commonly designated as chronic respiratory disease in chickens and as infectious sinusitis in turkeys. Infection may also be seen in pheasants, chukar partridges, and peafowl. Infection in pigeons, quail, ducks, geese, and psittacine birds should be considered. Passerine-type birds are quite resistant, although M. gallisepticum is the major cause of natural outbreaks of conjunctivitis in wild house finches (Carpodacus mexicanus) in the eastern USA (Merck Vet Manual: M. gallisepticum).
>gi|31544686|ref|NP_853264.1| dihydrolipoamide dehydrogenase (E3) component of pyruvate dehydrogenase complex [Mycoplasma gallisepticum str. R(low)]
MVLNMYNYDLIVIGAGPGGYVAGEHAAKNGLKTLVIERGTYGGVCLNVGCIPTKTLLQSSKVKHYIEKAA
EYGLDLVNNQLSVNWANILKRKEAVVNKLVNGVKTILKVAKADTIVGEARIVDGHTVTVNNQTFYITTKD
IIVATGSSPRKLPLPGFDQGRAEGVIIESTKALELPQIPQSLVVIGGGVIGIEFAMLYASLGTKVTILQA
VDRLCELLDQDASDFIAKRMKSLGVNVVYNAKILGYQNNAIIYEDNGTAYQLPSQYILESVGRVVNDQVF
GSFNVARDDRNRIKLNDKLQTSTDSIYVIGDAAGQIMLAHYAYHQALYAVDTILNRKTKKLSSLTTPGCI
YTYPEIATIGYTEQQLKEKNIEYVVSKMPMAVNGKAIADGSTEGFIKFMFGKKYGEILGCVLIASTASDM
ISEIALAMENELTVFELEQAIHPHPTIAEIISECAKQAIYNHFNKKH
Molecule Role :
Virmugen
Molecule Role Annotation :
An lpd mutant is highly attenuated in chickens and induces significant protection from challenge with wild type M. gallisepticum (Gates et al., 2008).
Molecule Role Annotation :
An antiserum raised in chicken against the TM-1 polypeptide, which was produced by recombinant Escherichia coli cells and purified by column chromatography, inhibited growth of M.g. cells in vitro. Moreover, chickens immunized with this 29 kDa polypeptide (TM-1) were partially protected from a challenge with virulent M.g (Saito et al., 1993).
Vaccination Protocol:
Eight-week-old specific pathogen-free (SPF) chickens were immunized subcutaneously in the right thigh with the TM-1 polypeptide, suspended in a mixture of 1 ml of PBS and 1 ml of an aluminium hydroxide adjuvant (Saito et al., 1993).
Challenge Protocol:
Four weeks later, the immunized chickens were challenged intranasally with 0.5 ml of a suspension of 10^6 c.f.u, ml- 1 of M.g. KP13 strain 27 (Saito et al., 1993).
Efficacy:
Only one of five immunized chickens harboured viable M.g. cells in its sinuses after being killed 5 days after challenge with M.g. (Saito et al., 1993).
4. Mycoplasma Gallisepticum Live Culture Vaccine (USDA: 1751.00)
a. Manufacturer:
Intervet Inc., Lohmann Animal Health International, Merial, Inc.
Persistence:
An lpd mutant is highly attenuated in chickens (Gates et al., 2008).
Efficacy:
An lpd mutant induces significant protection in chickens from challenge with wild type Mycoplasma gallisepticum (Gates et al., 2008).
Host Gene Response of
IgG Fc fragment
Gene Response:
Mg 7 vaccinated chickens mounted a strong humoral anti-M. gallisepticum-specific IgG response that was sustained for at least 4 weeks post-exposure. M. gallisepticum-specific immunoglobulin responses were detected in chickens inoculated with either Mg 7 or R(low) but not in chickens that received 1× PBS alone. The level of M. gallisepticum-specific serum IgG was highest in the R(low) treated animals at both the 2- and 4-week time points, however, the Mg 7 inoculated birds mounted a fairly robust response considering its level of attenuation. Thus, the Mg 7 vaccine induced significantly higher IgG responses than PBS inoculated chickens, but significantly lower than those inoculated with wild type R(low) (Gates et al., 2008).
Live temperature-sensitive mutant strain; eye drop administration(Barbour et al., 2000)
V. References
1. Barbour et al., 2000: Barbour EK, Hamadeh SK, Eidt A. Infection and immunity in broiler chicken breeders vaccinated with a temperature-sensitive mutant of Mycoplasma gallisepticum and impact on performance of offspring. Poultry science. 2000; 79(12); 1730-1735. [PubMed: 11194034].
2. Gates et al., 2008: Gates AE, Frasca S, Nyaoke A, Gorton TS, Silbart LK, Geary SJ. Comparative assessment of a metabolically attenuated Mycoplasma gallisepticum mutant as a live vaccine for the prevention of avian respiratory mycoplasmosis. Vaccine. 2008; 26(16); 2010-2019. [PubMed: 18342996].
4. Saito et al., 1993: Saito S, Fujisawa A, Ohkawa S, Nishimura N, Abe T, Kodama K, Kamogawa K, Aoyama S, Iritani Y, Hayashi Y. Cloning and DNA sequence of a 29 kilodalton polypeptide gene of Mycoplasma gallisepticum as a possible protective antigen. Vaccine. 1993; 11(10); 1061-1066. [PubMed: 8212828].
5. Wijesurendra et al., 2017: Wijesurendra DS, Kanci A, Tivendale KA, Devlin JM, Wawegama NK, Bacci B, Noormohammadi AH, Markham PF, Browning GF. Immune responses to vaccination and infection with Mycoplasma gallisepticum in turkeys. Avian pathology : journal of the W.V.P.A. 2017; 46(5); 464-473. [PubMed: 28345962].
